Showing papers on "Plant breeding published in 2014"
TL;DR: For millennia, humans have modified plant genes in order to develop crops best suited for food, fiber, feed, and energy production as discussed by the authors, but the recombination of DNA in offspring was random and often yielded crop varieties with unforeseen and undesirable properties.
Abstract: For millennia, humans have modified plant genes in order to develop crops best suited for food, fiber, feed, and energy production. The earliest efforts, far predating Gregor Mendel’s 19th-century discoveries on trait inheritance, involved the selective breeding of plants with desirable characteristics, but the recombination of DNA in offspring was random. Consequently, plant breeding often took decades and frequently yielded crop varieties with unforeseen and undesirable properties. Today, conventional plant breeding remains inherently random and slow, constrained by the availability of desirable traits in closely related plant species. In contrast, agricultural biotechnology employs the modern tools of genetic engineering to reduce uncertainty and breeding time and to transfer traits from more distantly related plants. Arguments in support of and in opposition to the use of genetically engineered seeds have changed little since the technology emerged in the 1980s. On one side, critics express concerns that the technology imposes negative environmental effects and jeopardizes the health of those who consume the “frankenfoods.” On the other side, supporters emphasize potential gains from boosting output and lowering food prices for consumers. They argue that such gains are achieved contemporaneous with the adoption of farming practices that lower agrochemical use and lessen soil
169 citations
TL;DR: A set of 381 accessions comprising 378 Upland (Gossypium hirsutum L.) and 3 G. barbadense L. accessions of the United States cotton belt were genotyped using 120 genome-wide SSR markers to establish the genetic diversity and population structure in tetraploid cotton.
Abstract: Genetic diversity and population structure in the US Upland cotton was established and core sets of allelic richness were identified for developing association mapping populations in cotton.
Elite plant breeding programs could likely benefit from the unexploited standing genetic variation of obsolete cultivars without the yield drag typically associated with wild accessions. A set of 381 accessions comprising 378 Upland (Gossypium
hirsutum L.) and 3 G.
barbadense L. accessions of the United States cotton belt were genotyped using 120 genome-wide SSR markers to establish the genetic diversity and population structure in tetraploid cotton. These accessions represent more than 100 years of Upland cotton breeding in the United States. Genetic diversity analysis identified a total of 546 alleles across 141 marker loci. Twenty-two percent of the alleles in Upland accessions were unique, specific to a single accession. Population structure analysis revealed extensive admixture and identified five subgroups corresponding to Southeastern, Midsouth, Southwest, and Western zones of cotton growing areas in the United States, with the three accessions of G. barbadense forming a separate cluster. Phylogenetic analysis supported the subgroups identified by STRUCTURE. Average genetic distance between G. hirsutum accessions was 0.195 indicating low levels of genetic diversity in Upland cotton germplasm pool. The results from both population structure and phylogenetic analysis were in agreement with pedigree information, although there were a few exceptions. Further, core sets of different sizes representing different levels of allelic richness in Upland cotton were identified. Establishment of genetic diversity, population structure, and identification of core sets from this study could be useful for genetic and genomic analysis and systematic utilization of the standing genetic variation in Upland cotton.
138 citations
TL;DR: Analysis of gene action for grain yield across plant densities emphasized the prominence of additivity, the increasing importance of nonadditivity as plant density and environmental stress levels increased, and genotype by environment interaction.
Abstract: A broad range of U.S. maize (Zea mays L.) germplasm was evaluated for plant density tolerance (PDT) to identify potential sources of favorable alleles and to obtain a better understanding the underlying genetics involved. Thirty-two hybrids created using a set of inbreds representing parentage of key heterotic subgroups were evaluated at plant densities ranging from 47,000 (19,000 plants per acre [ppA]) to 133,000 plants ha-1 (54,000 ppA). Forty-eight phenotypic traits from five categories (photosynthetic capability, plant architecture, growth responses, source– sink relationship, and general stress tolerance) as well as grain yield were evaluated in three environments that differed for levels of soil moisture availability. The relationship between plant density and grain yield was assessed for each hybrid, with a wide range of responses observed. Five hybrids showed substantial tolerance to plant densities ≥116,000 plants ha-1 based on grain yield performance. Phenotypic trait correlations revealed a subset of traits associated with grain yield across plant densities, with all five categories of traits implicated directly; the subset included leaf angle, upper stem diameter, leaf area required to produce a gram of grain, kernel rows per ear, days to canopy closure, barrenness, kernels per plant, kernel length, leaf number, upper leaf area, staygreen, zipper effect, kernels per row, and anthesis–silking interval. Analysis of gene action for grain yield across plant densities emphasized the prominence of additivity, the increasing importance of nonadditivity as plant density and environmental stress levels increased, and genotype by environment interaction. This work paves the way for further characterization of PDT through quantitative trait locus mapping and candidate gene approaches. Department of Crop Sciences and the Illinois Plant Breeding Center, University of Illinois at Urbana-Champaign,1102 S. Goodwin Ave., Urbana, IL 61801; B.D. Mansfield, present address: Northwestern Illinois Agricultural Research and Education Center, 321 210th Ave., Monmouth, IL 61462. This work was funded in part by USDA National Institute of Food and Agriculture, grant award 2010-85117-20532. B.D. Mansfield was supported in part in his graduate studies through the William B. and Nancy L. Ambrose Fellowship in Crop Sciences. Received 17 Apr. 2013. *Corresponding author (ritamumm@illinois.edu). Abbreviations: ASI, anthesis–silking interval; b1, slope; bu/A, bushels per acre; E, environment; Env1, Environment 1; Env2, Environment 2; Env3, Environment 3; GCA, general combining ability; H2, broadsense heritability; h2, narrow-sense heritability; HA, alternate hypothesis; MINN13, Minnesota13; NSS, non-Stiff Stalk Synthetic; QTL, quantitative trait locus; PDT, pant density tolerance; ppA, plants per acre; PVP, Plant Variety Protection; SCA, specific combining ability; SSS, Stiff Stalk Synthetic. Published in Crop Sci. 54:157–173 (2014). doi: 10.2135/cropsci2013.04.0252 © Crop Science Society of America | 5585 Guilford Rd., Madison, WI 53711 USA All rights reserved. No part of this periodical may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, recording, or any information storage and retrieval system, without permission in writing from the publisher. Permission for printing and for reprinting the material contained herein has been obtained by the publisher.
121 citations
TL;DR: The genetic variability identified in this research for root traits can be exploited to improve drought tolerance and/or resource capture in wheat.
Abstract: Root traits influence the amount of water and nutrient absorption, and are important for maintaining crop yield under drought conditions. The objectives of this research were to characterize variability of root traits among spring wheat genotypes and determine whether root traits are related to shoot traits (plant height, tiller number per plant, shoot dry weight, and coleoptile length), regions of origin, and market classes. Plants were grown in 150-cm columns for 61 days in a greenhouse under optimal growth conditions. Rooting depth, root dry weight, root: shoot ratio, and shoot traits were determined for 297 genotypes of the germplasm, Cultivated Wheat Collection (CWC). The remaining root traits such as total root length and surface area were measured for a subset of 30 genotypes selected based on rooting depth. Significant genetic variability was observed for root traits among spring wheat genotypes in CWC germplasm or its subset. Genotypes Sonora and Currawa were ranked high, and genotype Vandal was ranked low for most root traits. A positive relationship (R2≥0.35) was found between root and shoot dry weights within the CWC germplasm and between total root surface area and tiller number; total root surface area and shoot dry weight; and total root length and coleoptile length within the subset. No correlations were found between plant height and most root traits within the CWC germplasm or its subset. Region of origin had significant impact on rooting depth in the CWC germplasm. Wheat genotypes collected from Australia, Mediterranean, and west Asia had greater rooting depth than those from south Asia, Latin America, Mexico, and Canada. Soft wheat had greater rooting depth than hard wheat in the CWC germplasm. The genetic variability identified in this research for root traits can be exploited to improve drought tolerance and/or resource capture in wheat.
107 citations
TL;DR: The next generation plant breeding would demand more efficient technologies to develop low cost, high-throughput genotyping for screening large populations within a smaller time frame.
Abstract: As a term, “next generation plant breeding” is increasingly becoming popular in crop breeding programmes, conferences, scientific fora and social media (Schnable, 2013). Being a frontier area of crop science and business, it is gaining considerable interest among scientific community and policymakers and funds flow from entrepreneurs and research funding agencies. Plant breeding is a continuous attempt to alter genetic architecture of crop plants for efficient utilization as food, fodder, fiber, fuel or other end uses. Although the scientific concepts in plant breeding originated about 100 years ago, domestication and selection of desirable plants from prehistoric periods have contributed tremendously to ensure human food security (Gepts, 2004). During the past few decades, well supported crop improvement programmes for major crops started reaping benefits from cutting edge technologies of biological sciences, particularly in the form of molecular markers and transgenic crop development, which in combination with conventional phenotype based selection, defines the current generation plant breeding practices. Different types of molecular markers have been developed and extensively used during the last three decades for identifying linkage between genes and markers, discovering quantitative trait loci (QTLs), pyramiding desired genes and performing marker assisted foreground and background selections for introgression of desired traits (Varshney and Tuberosa, 2007). However, these markers are based mostly on electrophoretic separation of DNA fragments, which limits detection of genetic polymorphism. In large plant breeding populations, genotyping may take up several months depending on marker system, adding more cost to genotyping. The next generation plant breeding would thus demand more efficient technologies to develop low cost, high-throughput genotyping for screening large populations within a smaller time frame.
74 citations
TL;DR: A novel chlorophyll-deficient chlorina tea plant cultivar was identified and the expression of 259 genes related to amino acid metabolism, photosynthesis and pigment metabolism was significantly altered in ZH2 shoots compared with those of LJ43 plants.
Abstract: Background
The tea plant (Camellia sinensis (L.) O. Kuntze) is one of the most economically important woody crops. Recently, many leaf color genotypes have been developed during tea plant breeding and have become valuable materials in the processing of green tea. Although the physiological characteristics of some leaf color mutants of tea plants have been partially revealed, little is known about the molecular mechanisms leading to the chlorina phenotype in tea plants.
71 citations
TL;DR: Lentil cultivars revealed clear clustering based on geographical origin, but much more limited correlation between geographic origin and genetic diversity was observed for landraces, suggesting that selection of divergent parental genotypes for breeding should be made actively on the basis of systematic assessment of genetic distance between genotypes, rather than passively based on geographic distance.
Abstract: Lentil is a self-pollinated annual diploid (2n = 2× = 14) crop with a restricted history of genetic improvement through breeding, particularly when compared to cereal crops. This limited breeding has probably contributed to the narrow genetic base of local cultivars, and a corresponding potential to continue yield increases and stability. Therefore, knowledge of genetic variation and relationships between populations is important for understanding of available genetic variability and its potential for use in breeding programs. Single nucleotide polymorphism (SNP) markers provide a method for rapid automated genotyping and subsequent data analysis over large numbers of samples, allowing assessment of genetic relationships between genotypes. In order to investigate levels of genetic diversity within lentil germplasm, 505 cultivars and landraces were genotyped with 384 genome-wide distributed SNP markers, of which 266 (69.2%) obtained successful amplification and detected polymorphisms. Gene diversity and PIC values varied between 0.108-0.5 and 0.102-0.375, with averages of 0.419 and 0.328, respectively. On the basis of clarity and interest to lentil breeders, the genetic structure of the germplasm collection was analysed separately for cultivars and landraces. A neighbour-joining (NJ) dendrogram was constructed for commercial cultivars, in which lentil cultivars were sorted into three major groups (G-I, G-II and G-III). These results were further supported by principal coordinate analysis (PCoA) and STRUCTURE, from which three clear clusters were defined based on differences in geographical location. In the case of landraces, a weak correlation between geographical origin and genetic relationships was observed. The landraces from the Mediterranean region, predominantly Greece and Turkey, revealed very high levels of genetic diversity. Lentil cultivars revealed clear clustering based on geographical origin, but much more limited correlation between geographic origin and genetic diversity was observed for landraces. These results suggest that selection of divergent parental genotypes for breeding should be made actively on the basis of systematic assessment of genetic distance between genotypes, rather than passively based on geographical distance.
64 citations
TL;DR: In this article, the root growth, nitrogen uptake, dry matter accumulation and yield formation of six maize hybrids released from 1973 to 2000 in China were compared under low and high nitrogen supply in a black soil in Northeast China.
Abstract: Modern maize breeding has increased maize yields worldwide The changes in above-ground traits accompanying yield improvement are well-known, but less information is available as to the effect of modern plant breeding on changes in maize root traits Root growth, nitrogen uptake, dry matter accumulation and yield formation of six maize hybrids released from 1973 to 2000 in China were compared Experiments were conducted under low and high nitrogen supply in a black soil in Northeast China in 2010 and 2011 While nitrogen accumulation, dry matter production and yield formation have been increased, modern maize breeding in China since 1990 has reduced root length density in the topsoil without much effect on root growth in the deeper soil The efficiency of roots in acquiring N has increased so as to match the requirement of N accumulation for plant growth and yield formation The responses of root growth, nitrogen and dry matter accumulation, and grain yield to low-N stress were similar in the more modern hybrids as in the older ones Modern maize breeding has constitutively changed root and shoot growth and plant productivity without producing any specific enhancement in root responsiveness to soil N availability
60 citations
TL;DR: Overall a negative slope in the heat treatment indicated that a cooler canopy provided a yield benefit under stress, and implementing selection strategies for CT may have potential for breeding tolerant genotypes.
Abstract: Developing cultivars with improved adaptation to drought and heat stressed environments is a priority for plant breeders. Canopy temperature (CT) is a useful tool for phenotypic selection of tolerant genotypes, as it integrates many physiological responses into a single low-cost measurement. The objective of this study was to determine the ability of CT to predict grain yield within the flow of a wheat breeding program and assess its utility as a tool for indirect selection. CT was measured in both heat and drought stressed field experiments in northwest Mexico on 18 breeding trials totaling 504 spring wheat lines from the International Maize and Wheat Improvement Center (CIMMYT) Irrigated Bread Wheat program. In the heat treatment, CT was significantly correlated with yield (r = −0.26) across all trials, with a maximum coefficient of determination within the individual trials of R2 = 0.36. In the drought treatment, a significant correlation across all trials was only observed when days to heading or plant height was used as a covariate. However, the coefficient of determination within individual trials had a maximum of R2 = 0.54, indicating that genetic background may impact the ability of CT to predict yield. Overall a negative slope in the heat treatment indicated that a cooler canopy provided a yield benefit under stress, and implementing selection strategies for CT may have potential for breeding tolerant genotypes.
59 citations
TL;DR: The pool of Central American accessions showed very large genetic variation as assessed by DNA-marker variation compared to accessions from other regions and showed the highest phenotypic variation and should be considered as the most important source for plant breeding.
Abstract: Background: The main bottleneck to elevate jatropha (Jatropha curcas L.) from a wild species to a profitable biodiesel crop is the low genetic and phenotypic variation found in different regions of the world, hampering efficient plant breeding for productivity traits. In this study, 182 accessions from Asia (91), Africa (35), South America (9) and Central America (47) were evaluated at genetic and phenotypic level to find genetic variation and important traits for oilseed production. Results: Genetic variation was assessed with SSR (Simple Sequence Repeat), TRAP (Target Region Amplification Polymorphism) and AFLP (Amplified fragment length polymorphism) techniques. Phenotypic variation included seed morphological characteristics, seed oil content and fatty acid composition and early growth traits. Jaccard’s similarity and cluster analysis by UPGM (Unweighted Paired Group Method) with arithmetic mean and PCA (Principle Component Analysis) indicated higher variability in Central American accessions compared to Asian, African and South American accessions. Polymorphism Information Content (PIC) values ranged from 0 to 0.65. In the set of Central American accessions. PIC values were higher than in other regions. Accessions from the Central American population contain alleles that were not found in the accessions from other populations. Analysis of Molecular Variance (AMOVA; P < 0.0001) indicated high genetic variation within regions (81.7%) and low variation across regions (18.3%). A high level of genetic variation was found on early growth traits and on components of the relative growth rate (specific leaf area, leaf weight, leaf weight ratio and net assimilation rate) as indicated by significant differences between accessions and by the high heritability values (50–88%). The fatty acid composition of jatropha oil significantly differed (P < 0.05) between regions. Conclusions: The pool of Central American accessions showed very large genetic variation as assessed by DNA-marker variation compared to accessions from other regions. Central American accessions also showed the highest phenotypic variation and should be considered as the most important source for plant breeding. Some variation in early growth traits was found within a group of accessions from Asia and Africa, while these accessions did not differ in a single DNA-marker, possibly indicating epigenetic variation.
59 citations
TL;DR: The results suggest the utility of the developed phenotyping approaches for applied plant breeding and the potential of the traits to assist in the design of the male ideotype for increased cross-fertilization.
Abstract: Hybrid breeding is a promising approach to increase the yield potential in wheat (Triticum aestivum L.). The profitability of wheat hybrids highly depends on a cost-efficient system for hybrid seed production for which an adequate outcrossing in the male pool is of utmost importance. Employing a set of 51 elite winter wheat lines, we developed and evaluated phenotyping methods for floral and flowering traits with relevance for improved cross-pollination. We observed significant genotypic variances and high heritabilities for most traits, including important traits like pollen mass and anther extrusion. Our results suggest the utility of the developed phenotyping approaches for applied plant breeding and the potential of the traits to assist in the design of the male ideotype for increased cross-fertilization.
TL;DR: GZnC is determined in a recombinant inbred line population from the cross between PBW343 and Kenya Swara in replicated trials grown in Zn-enriched field and the closely linked markers identified will make selection for this difficult trait feasible in breeding program.
Abstract: Zinc deficiency in humans is recognized as a widespread public health problem worldwide, but can be combated via genetic biofortification through breeding high zinc containing wheat varieties. CIMMYT (International Maize and Wheat Improvement Center, Int.) is engaged in enhancing, among others, the grain zinc concentration (GZnC) of high-yielding wheat germplasm under the HarvestPlus initiative of the Consultative Group on International Agricultural Research consortium. In the present study, we determined GZnC in a recombinant inbred line population from the cross between PBW343 and Kenya Swara in replicated trials grown in Zn-enriched field. An integrated genetic map with 1,133 loci (diversity arrays technology and simple sequence repeats markers) covering all 21 wheat chromosomes was constructed and used for quantitative trait loci (QTL) analysis. Two novel QTL of large effect were stably detected for increasing GZnC on chromosomes 2Bc (centromeric region) and 3AL (long arm). The two QTL individually explained about 10–15 % of the total phenotypic variation. The 2Bc QTL from PBW343 have pleiotropic effect and can increase thousand-kernel weight at significant level. The QTL and the closely linked markers identified will make selection for this difficult trait feasible in breeding program.
TL;DR: A number of useful traits in the gene pools and a wide range of phenotypic variation that provides a good source of diversity for use in modern faba bean breeding programmes are indicated.
Abstract: Faba bean is cultivated worldwide and widely used in Mediterranean countries, Asia and Europe. However, only a few faba bean breeders are active in cultivar development. As a result, a limited number of varieties are available for growers. Plant genetic resources or germplasm are fundamental sources for plant breeding, and the assessment of the genetic diversity among germplasm accessions is useful to facilitate more efficient use of plant genetic resources. A mini-core collection of faba bean germplasm (178 landraces and four cultivars), from diverse geographic regions of Turkey, was assessed for agro-morphological performance and some quality traits. There were substantial variations for the investigated morphological and quality characteristics. The analysis of variance revealed that the differences among 182 accessions were significant for all the studied characters. Some accessions showed very good agronomic performance for some traits. Positive and negative correlations existed among different morphological and agronomic traits. Landraces have been classified into four different groups using a cluster analysis. These results suggest that an a priori classification of accessions according to the growing area does not strictly correspond to phenotypic grouping. From the spatial distribution of landraces, however, it has been possible to identify ‘superior’ accessions of some traits. These findings indicate a number of useful traits in the gene pools and a wide range of phenotypic variation that provides a good source of diversity for use in modern faba bean breeding programmes.
TL;DR: A population of recombinant inbred lines was developed for one of the best crosses of the Spanish National Barley Breeding Program, between two six-row winter barley cultivars Orria and Plaisant, and QTLs suitable for MAS for most traits were identified.
Abstract: Advances in plant breeding through marker-assisted selection (MAS) are only possible when genes or quantitative trait loci (QTLs) can contribute to the improvement of elite germplasm. A population of recombinant inbred lines (RILs) was developed for one of the best crosses of the Spanish National Barley Breeding Program, between two six-row winter barley cultivars Orria and Plaisant. The objective of this study was to identify favourable QTLs for agronomic traits in this population, which may help to optimise breeding strategies for these and other elite materials for the Mediterranean region. A genetic linkage map was developed for 217 RILs, using 382 single nucleotide polymorphism markers, selected from the barley oligonucleotide pool assay BOPA1 and two genes. A subset of 112 RILs was evaluated for several agronomic traits over a period of 2 years at three locations, Lleida and Zaragoza (Spain) and Fiorenzuola d’Arda (Italy), for a total of five field trials. An important segregation distortion occurred during population development in the region surrounding the VrnH1 locus. A QTL for grain yield and length of growth cycle was also found at this locus, apparently linked to a differential response of the VrnH1 alleles to temperature. A total of 33 QTLs was detected, most of them for important breeding targets such as plant height and thousand-grain weight. QTL × environment interactions were prevalent for most of the QTLs detected, although most interactions were of a quantitative nature. Therefore, QTLs suitable for MAS for most traits were identified.
TL;DR: The hypothesis that A. donax may be a polyploid derived from Arundo plinii is advanced, as a high correlation between parent–progeny for the traits culm height and culm diameter and a heritability of 0.34 which appeared promising for clonal selection.
Abstract: Arundo donax is a perennial rhizomatous plant growing spontaneously all over the world as an invasive plant reaching more than 8 m in height. It is a sterile plant which reproduces itself only agamically, through rhizomes and cane fragments which are transported by water or through human action. Although A. donax is an invasive plant it is considered one of the most promising energy crops, as it is characterized by a high energy balance. In this work we collected 87 A. donax clones from around Italy and with the aim of characterizing the genetic structure of the population, we studied the genetic diversity by using molecular markers (a survey of SSRs and genes from maize) and, for the first time, by sequence comparison using the purple plantl1 maize homologous orthologous gene. The results obtained showed a low genetic diversity as expected for an agamic plant. However, although MANTEL analysis did not show any statistical difference regarding the geographical distribution of these clones, we noticed by PCA/AMOVA analysis the presence of three different genotypes. Among a survey of eight clones studied in detail we found a high correlation between parent–progeny for the traits culm height and culm diameter and a heritability (h2) of the same traits respectively of 0.21 and 0.34 which appeared promising for clonal selection. Finally based on data collected regarding molecular analysis, chromosome number, epidermal cell size and chlorophyll content, we advance the hypothesis that A. donax may be a polyploid derived from Arundo plinii.
TL;DR: The information on variations in yield and agronomic traits detected in this study provided useful parents for rapeseed breeding and may be used in subsequent genome-wide association studies for B. napus.
Abstract: It is important to evaluate yield and agronomic traits when selecting for elite lines in Brassica napus L. In this study, 488 global collections of B. napus L. were evaluated for yield and agronomic traits during two consecutive years under growing conditions in central China. A series of phenotypic data for yield and agronomic traits were obtained. Large variations in yield and agronomic traits were found among these accessions, making selection possible for these characters. Chinese accessions, in general, tended to have higher plot yield (POY), higher seed yield per plant (PY), higher thousand-seed weight (TSW), more seeds per silique (SS), and fewer siliques per plant (PS) than foreign accessions. Comparing winter, semi-winter, and spring accessions, semi-winter accessions tended to have the highest POY, highest PY, highest TSW, most SS and fewest PS. Genotypic variation for TSW accounted for 71.23 % of the total variation, and it was the highest for all 12 of the phenotypic traits. Significant correlations were observed between different traits. Principal component analysis (PCA) revealed that significant variation among the traits with the first four principal components could explain 49.8 % of the total variation. Three major groups (winter, spring and semi-winter oilseed rape accessions) could be distinguished when projecting the accessions onto the first two PCAs. The information on variations in yield and agronomic traits detected in this study provided useful parents for rapeseed breeding. Moreover, the phenotypic data on yield and agronomic traits obtained may be used in our subsequent genome-wide association studies for B. napus.
TL;DR: The transgene introgression of a high-iron trait into aHigh-yielding indica rice cultivar through interbreeding between soybean ferritin-overexpressing transgenic IR68144 and the high-y yielding cultivar Swarna is reported here.
Abstract: Low level of iron in staple food crops is one reason for the predominance of iron-deficiency anemia in developing countries. Most of the iron in rice grains accumulates in the outer aleurone layer and embryo, which are removed during milling, and the edible endosperm contains very low amounts of iron. In an effort to increase iron nutrition, we report here the transgene introgression of a high-iron trait into a high-yielding indica rice cultivar. The ferritin gene from soybean (soyfer1) was introduced into rice plants through interbreeding between soybean ferritin-overexpressing transgenic IR68144 and the high-yielding cultivar Swarna. The stable integration of the soyfer1 gene was confirmed in the BC2F4 generation, and the hybrid seeds showed 2.6-fold soybean ferritin gene expression over the recurrent parent Swarna. The hybrid milled seeds revealed a 2.54-fold increase in iron and 1.54-fold increase in zinc compared to Swarna. Agronomic data and an SSR marker analysis of the hybrid rice plants were taken into account for NIL character identification.
TL;DR: By using embryo rescue to save vital embryos as well as shorten the breed cycle of sorghum, the breeding cycle was made comparable or even shorter than that of other model crops, which would allow the development of breeding materials much faster.
Abstract: Sorghum [ Sorghum bicolor (L.) Moench] is a model C4 cereal for both basic and applied research. It has most of the traits of a model plant species: large embryos that are easy to rescue, moderate genome size of about 760 Mb, several unique traits not found in other species, plenty of seeds, and many important agronomic as well as commercial uses. However, it takes a long time to complete its breeding cycle. ther oproblems encountered during the research on sorghum breeding were early desiccation of embryos from mutants and wide hybridization, and the high-yielding cultivars and plants grown in controlled environments are usually uniculm, which limits their use in crossing to obtain both selfed and crossed seeds. The objective of this research was to find ways to obtain cross- and self-pollinated seeds from the same plant, con-serve the vital embryos, and most important, shorten the breeding cycle. Two methods are reported here. The first method was to produce crossed as well as selfed seeds on the same panicle of the usually uni-culm plant. The sec-ond method was to carry out embryo rescue to save vital embryos as well as shorten the breed -ing cycle from the regular 17 to 11 wk. By these two methods, the breeding cycle of sorghum was made comparable or even shorter than that of other model crops, which would allow the development of breeding materials much faster.G. Rizal, S. Karki, M. Alcasid, F. Montecillo, K. Acebron, N. Larazo, R. Garcia, and W.P. Quick, C4 Rice Center, International Rice Res. Institute, Los Banos, Laguna, DAPO Box 7777, Metro-Manila, Philip -pines; I.H. Slamet-Loedin, Plant Breeding, Genetics and Biotechnology Division, International Rice Research Institute, Los Banos, Laguna, DAPO Box 7777, Metro-Manila, Philippines; W.P. Quick, Dep. of Animal and Plant Sciences, Univ. of Sheffield, Sheffield, UK. G. Rizal, and S. Karki contributed equally. Received 19 July 2013. *Correspond -ing author (w.p.quick@irri.org).
TL;DR: Evaluating the genetic architecture of PUE in tropical maize using multiple interval mapping for design III in a population of 140 RILs backcrossed with both parental lines showed that dominance effects were more important than additive effects for explaining the variations in PUE and its components.
Abstract: Phosphorus (P) deficiency is a major limiting factor for crop production in several countries. A better understanding of the genetic components of P use efficiency (PUE) is required to improve crop performance in low-P soils. To date, no QTLs (quantitative trait loci) were mapped for PUE using grain yield and other late phenotypic data in tropical conditions. Thus, we evaluated the genetic architecture of PUE in tropical maize (Zea mays L.) using multiple interval mapping for design III in a population of 140 RILs (recombinant inbred lines) backcrossed with both parental lines. The parental lines contrasted for yield and for PUE, a phenotypic index that was further decomposed into P acquisition efficiency (PAE) and P utilization efficiency. Our results showed that dominance effects were more important than additive effects for explaining the variations in PUE and its components. Approximately 80% of the QTLs mapped for PAE co-localized with those for PUE, indicating that the efficiency in acquiring P is the main determinant of PUE in tropical maize. Also, QTLs for PUE and PAE were located near to candidate genes previously associated with root development. Thus, we present important information to guide breeding strategies for the development of maize cultivars more adapted to P deficiency. F.F. Mendes, C.T. Guimaraes, L.J.M Guimarães, P.E.O. Guimarães, J.V. Magalhaes, and S.N. Parentoni, Embrapa Milho e Sorgo, CP 285, 35701970, Sete Lagoas, MG, Brazil; J.C. Souza, Dep. de Biologia, Univ. Federal de Lavras, CP 37, 37200-000, Lavras, MG, Brazil; A.A.F. Garcia, Dep. de Genética, Escola Superior de Agricultura Luiz de Queiroz, Univ. de São Paulo CP 83, 13400-970, Piracicaba, SP, Brazil. Received 14 Nov. 2013. *Corresponding author (claudia.guimaraes@embrapa.br). Abbreviations: GY, grain yield; LOD, logarithm of odds; MIM, multiple interval mapping; PAE, phosphorus acquisition efficiency; Psoil, phosphorus soil content; PUE, phosphorus use efficiency; PUTIL, phosphorus internal utilization efficiency; QTL, quantitative trait loci; RIL, recombinant inbred line; SDW, shoot dry weight. Published in Crop Sci. 54:1530–1538 (2014). doi: 10.2135/cropsci2013.11.0755 Freely available online through the author-supported open-access option. © Crop Science Society of America | 5585 Guilford Rd., Madison, WI 53711 USA All rights reserved. No part of this periodical may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, recording, or any information storage and retrieval system, without permission in writing from the publisher. Permission for printing and for reprinting the material contained herein has been obtained by the publisher. Published April 28, 2015
TL;DR: The main aim of this paper was to show the level of genetic diversity of Polish oat cultivars which were bred before 1939, and it is very probable that the gene pools of early and contemporary cultivars could be separable.
Abstract: In Poland oat breeding began at the late nineteenth century. During the World War II almost all of Polish breeding materials were lost, and then were replaced by German cultivars. The main aim of this paper was to show the level of genetic diversity of Polish oat cultivars which were bred before 1939. Simultaneously usefulness and informativeness of molecular and morphological methods were tested and compared. This study involved 23 cultivars, which were described by 25 morphological traits and three types of molecular markers (AFLP, ISSR and RAPD). Based on Dice coefficient, genetic distance between cultivars ranged from 0.17 to 0.44. The degree of morphological differentiation within the collection varied depending on trait. Nei’s genetic diversity for the combined results for the whole collection was equal to 0.202. Neither unweighted pair group method with arithmetic mean nor principal coordinate analysis showed any discrimination of cultivars according to breeding period and morphological trait. Part of morphological diversity has been preserved in the Polish early oat cultivars, do not exist anymore in contemporary cultivars, and also in landraces. The interest of breeders in early cultivars germplasm stored in genebank was and still is negligible. Breeding is confined to a few preferred by market morphotypes. So, it is very probable that the gene pools of early and contemporary cultivars could be separable.
TL;DR: Economic modelling strongly suggests that giving livestock access to green tedera in summer and autumn will dramatically increase farm profit by reducing supplementary feeding, and selected cultivars from the crossing and selfing program will deliver cultivars of three ideotypes.
Abstract: Tedera (Bituminaria bituminosa C.H. Stirton var. albomarginata and var. crassiuscula) has been identified as one of the most productive and drought-tolerant species of herbaceous perennial legumes based on 6 years of field evaluation in Western Australia in areas with Mediterranean climate and annual rainfall ranging from 200 to 600 mm. Importantly, tedera demonstrated broad adaptation to diverse soils, and some accessions have shown moderate levels of tolerance to waterlogging and salinity. Tedera exhibits minimal leaf shedding during summer and autumn. Economic modelling strongly suggests that giving livestock access to green tedera in summer and autumn will dramatically increase farm profit by reducing supplementary feeding. The breeding program (2006–12) evaluated the available genetic diversity of tedera for its field performance in seven nurseries with 6498 spaced plants in total covering a wide variation in rainfall, soils and seasons. Best overall plants were selected using a multivariate selection index generated with best linear unbiased predictors (BLUPs) of dry matter cuts and leaf retention traits. The breeding program also evaluated tedera for grazing tolerance, grazing preference by livestock, waterlogging tolerance, seed production, cold tolerance, disease susceptibility and presence of secondary compounds. Tedera is a diploid, self-pollinated species. Therefore, 28 elite parents were hand-crossed in several combinations to combine outstanding attributes of parents; F1 hybrids were confirmed with the aid of highly polymorphic, simple sequence repeat markers. The F1s were progressed to F4s by single-seed descent breeding. Elite parent plants were selfed for two generations to be progressed in the breeding program without hybridisation. Over time, selections from the crossing and selfing program will deliver cultivars of three ideotypes: (i) drought-tolerant, (ii) cold- and drought-tolerant, (iii) waterlogging- and drought-tolerant.
TL;DR: Tolerance is the major component in the resistance conferred by BPH7 and should be of great benefit for gene map-based cloning and in plant breeding programs for BPH-resistant rice lines.
Abstract: The brown planthopper (Nilaparvata lugens Stal; BPH) is a severe constraint to rice (Oryza sativa) production. A particularly important approach to controlling this insect pest is the identification and characterization of BPH resistance genes and the subsequent incorporation of the most effective ones into cultivars. Rice var. T12 has been reported to carry resistance gene BPH7 (previously designated bph7) that has not yet been assigned to a chromosome location and whose resistance mechanism is still unknown. In the study reported here we identified and mapped this gene using F2 and backcrossing populations and characterized its resistance in the rice var. 93-11 genetic background using near isogenic lines (NILs). Our analysis of the 93-11/T12 F2 population revealed that the BPH7 gene is located on the long arm of chromosome 12 between simple sequence repeat markers RM28295 and RM313. Subsequent fine mapping placed this gene more precisely in a region flanked by the markers RM3448 and RM313 which are 150 kb apart in the Nipponbare genome and 300 kb apart in the 93-11 genome. BPH7 explained 38.3 % of the phenotypic variance of BPH resistance in the F2 populations. Characterization of the BPH7-mediated resistance revealed that the settlement of the BPH on plants and the survival rate and population growth rate of the BPH were not different significantly between NIL-BPH7 and 93-11 plants. The NIL-BPH7 plants showed significant tolerance to the insects at the seedling and adult stages compared with the susceptible parent 93-11. Our results demonstrate that tolerance is the major component in the resistance conferred by BPH7. The gene mapping of BPH7 should be of great benefit for gene map-based cloning and in plant breeding programs for BPH-resistant rice lines.
TL;DR: This protocol was successful for the production of oat microspore-derived embryos and DH green plants with minimal albinism and further develop these embryos into fertile DH plants.
Abstract: The production of doubled haploid (DH) plants from microspores is an important technique used in plant breeding programs and basic research. Although doubled haploidy efficiencies in wheat and barley are sufficient for breeding purposes, oat (Avena sativa L.) is considered recalcitrant. The objective of this project was to develop a protocol for the production of microspore-derived embryos of oat and further develop these embryos into fertile DH plants. A number of experiments were conducted evaluating the factors influencing microspore embryogenesis, i.e. donor plant conditions, pretreatments, media composition, and culture conditions. The initial studies yielded little response, and it was not until high microspore densities (106 microspores/mL and greater) were used that embryogenesis was achieved. Depending on the treatment, yields of over 5,000 embryos/106 microspores were obtained for breeding line 2000QiON43. The doubled haploidy protocol includes: a 0.3 M mannitol pretreatment of the tillers for 7 days, culture in W14 basal medium with a pH of 6.5–7.5, a microspore density of 106 microspores/mL, and continuous incubation at 28 °C incubation. The resulting embryos observed after 28 days were plated onto solidified W14 medium with 0.8 or 1.0 g/L activated charcoal. A colchicine treatment of 0.2 % colchicine for 4 h resulted in conversion of 80 % of the plants from haploid to DH. This protocol was successful for the production of oat microspore-derived embryos and DH green plants with minimal albinism. DH seed was produced and planted for evaluation in a field nursery.
TL;DR: Wang et al. as discussed by the authors investigated the nucleotide variation at this gene, MsTAC1, in 33 M. sinensis accessions collected from different areas in China, and one genotype of Miscanthus × giganteus.
Abstract: Biomass yield is an important target trait in Miscanthus breeding for desirable energy crops. Tiller angle is a key trait of plant architecture because it determines planting density and further influences biomass yield through affecting photosynthesis efficiency. TAC1, a major gene involved in tiller and leaf angle control in rice and maize, respectively, has been extensively studied. Nucleotide variation at this gene, MsTAC1, was investigated in 33 Miscanthus sinensis accessions collected from different areas in China, and one genotype of Miscanthus × giganteus. A total of 136 loci, including 129 single base substitutions and seven InDels, occurred within the MsTAC1 gene of 1,874 bp. The genetic diversity at MsTAC1 is characterized by high nucleotide diversity (π value) and high heterozygosity. Clustering analysis indicated that the phylogenetic tree of the 33 M. sinensis accessions was correlated with their geographical sites of origin. The neutrality test revealed no strong selection pressure on coding and non-coding region variations of the MsTAC1 gene in the accessions. Phenotype evaluations were conducted for tiller angle and five other traits in the Miscanthus panels in the first two growth years of 2009 and 2010. Analysis of variance showed significant phenotypic variations in the examined traits. Association analysis using 246 markers detected 88 loci associated with all the test traits in either 1 or 2 years, and 11 of the 88 were year reproducible and thus reliable. These associations indicate that the variation of MsTAC1 affects the phenotypic value of the tiller angle, tiller number and biomass yield, suggesting that allelic variation in MsTAC1 affects multiple traits and demonstrates its significance in Miscanthus breeding programs.
TL;DR: Monitoring changes in the frequency of molecular DNA markers over time in wheat cultivars may yield insight into alleles linked to important traits that have been the subject of positive or negative selection in the past and that may be useful for marker-assisted breeding programs in the future.
Abstract: A collection of 189 bread wheat landraces and cultivars, primarily of European origin, released between 1886 and 2009, was analyzed using two DNA marker systems. A set of 76 SSR markers and ~7,000 DArT markers distributed across the wheat genome were employed in these analyses. All of the SSR markers were found to be polymorphic, whereas only 2,532 of the ~7,000 DArT markers were polymorphic. A Mantel test between the genetic distances calculated based on the SSR and DArT data showed a strong positive correlation between the two marker types, with a Pearson’s value (r) of 0.66. We assessed the genetic diversity and allelic frequencies among the accessions based on spring- versus winter-wheat type as well as between landraces and cultivars. We also analyzed the changes in genetic diversity and allelic frequencies in these samples over time. We observed separation based on both vernalization type and release date. Interestingly, we detected a decrease in genetic diversity in wheat accessions released over the period from 1960 to 1980. However, our results also showed that modern plant breeding have succeeded in maintaining genetic diversity in modern wheat cultivars. Studying allelic frequencies using SSR and DArT markers over time revealed changes in allelic frequencies for a number of markers that are known to be linked to important traits, which should be useful for genomic screening efforts. Monitoring changes in the frequency of molecular DNA markers over time in wheat cultivars may yield insight into alleles linked to important traits that have been the subject of positive or negative selection in the past and that may be useful for marker-assisted breeding programs in the future.
TL;DR: An ideal GDI value (0.37) for the two indica-japonica parents that could provide an optimal balance between the inter-subspecific heterosis and reproductive isolation was proposed and will help in the strategic design of an inter- subspecific hybrid rice breeding program by identifying the ideal indica and japonicaParents for a hybrid combination to achieve hybrid rice with an optimal yield.
Abstract: The application of heterosis (hybrid vigor) has brought great success to plant breeding, particularly of hybrid rice, achieving significant yield increases. Attempts to explore the heterosis of inter-subspecific hybrids between indica and japonica rice, which result in even greater yield increases, have greatly increased in the past decades. However, because of the reduced seed setting rate in F1 hybrids as a result of increased reproductive isolation, the application of inter-subspecific hybrids in rice has slowed. Understanding the balance between heterosis and the reproductive isolation of inter-subspecific hybrids will facilitate the strategic design of inter-subspecific hybrid breeding. In this study, five indica and seven japonica rice varieties were chosen as the parental lines of a complete diallel mating design. Data from six group traits from all of the hybrids and inbred lines were collected. We found that the grain weight per plant, grain number per panicle, tiller per plant, thousand grain weight and plant height, which reflected increased heterosis, were associated with the genetic divergence index (GDI) of the parents. Meanwhile, owing to the reduced seed setting rate, which was also associated with the parents' GDI, the grain production of the hybrids was negatively affected. After analyzing the relationships between the GDI of indica-japonica parents and the grain weight per plant of the F1 hybrids, an ideal GDI value (0.37) for the two indica-japonica parents that could provide an optimal balance between the inter-subspecific heterosis and reproductive isolation was proposed. Our findings will help in the strategic design of an inter-subspecific hybrid rice breeding program by identifying the ideal indica and japonica parents for a hybrid combination to achieve hybrid rice with an optimal yield. This strategic design of an inter-subspecific hybrid rice breeding program will be time saving and cost effective.
01 Jan 2014
TL;DR: In this article, the authors evaluated the genotypes of rice (Oryza sativa L.) for genetic variability and correlation. The experiment was conducted in the research area of department of Plant Breeding and Genetics, University of Agriculture Faisalabad, following randomized complete block design with three replications.
Abstract: Rice being the second most important staple food in Pakistan plays an important role in economic stability of Pakistan. An insight of genetic diversity and correlation among the various traits related to yield is helpful in this regard. Twenty genotypes of rice (Oryza sativa L.) were evaluated for genetic variability and correlation. The experiment was conducted in the research area of department of Plant Breeding and Genetics, University of Agriculture Faisalabad, following randomized complete block design with three replications. The data was recorded on yield and different yield components. The results pertaining to analysis of variance showed highly significant differences among all genotypes for all the yield trails. Flag leaf area, number of productive tillers per plant, number of spikelets per panicle, number of grains per panicle and 1000 grain weight had a highly positive significant genotypic correlation with grain yield per plant. Same results were obtained for the phenotypic correlation. The study of path analysis for yield related traits revealed that number of productive tillers per plant, number of spikelets per panicle, number of grains per panicle and days to maturity had positive direct effect on grain yield per plant. In view of the results obtained from this experiment, it may be concluded that the characters like number of productive tillers per plant, number of spikelets per panicle could be used as a direct selection criteria for higher grain yield. Genotypes like Sr1-57, Basmati-385, Srs-505, Ksk-133, Sr1-13 and DM-2-25-9- 2002 may be used to bring about improvement in rice grain yield by including these in rice breeding programs for development of commercial varieties. market and also for the high quality of the kernel. It provides 20% of the world's dietary energy supply, while wheat supplies 19% and maize 5 %. Rice is the predominant staple food for 17 countries in Asia and the Pacific, nine countries in Africa (Laxuman et al., 2011). In Pakistan rice is cultivated over an area of 2.88 million hectares with a production of 6.88 million tons annually with an average yield of 2.39 tons per hectare (Anonymous, 2009-2010). It accounts for 6.4% value added in agriculture and 1.4% in GDP (Anonymous, 09-10). Pakistan is the fifth biggest rice exporting country in the world and exports more than one million tons of rice annually, which is 10% of the world's rice trade. The need and importance of rice is increasing day by day due to the increase in the population explosion on earth. Therefore, it is the basic need of these days to boost up rice yield and quality through the development of biologically superior, stable and high yielding rice varieties to meet the increasing food demand.
01 Jan 2014
TL;DR: The range of techniques available for the isolation or induction of haploids by in vivo or by in vitro, estimation of haploid lavel either through chromosome counting or flowcytometry and also discourse the value ofhaploids are described.
Abstract: Majority of higher plants are outbreeding, highly heterozygous and undergo a long developmental period before reaching their reproductive stage. Traditional breeding and cross- pollinating procedures are both unpredictable and time-consuming. Haploids are plants with a gametophytic chromosome number and doubled haploids are haploids that have undergone chromosome duplication, represent a particularly attractive biotechnological method to accelerate plant breeding. They can occur either spontaneously or can be induced by modified pollination methods in vivo, or by in vitro culture of immature male or female gametophytes. Biotechnologies provide powerful tools for plant breeding, and among these ones, tissue culture, particularly haploid and doubled haploid technology, can effectively help to select superior plants. In vitro haploid production is, thus, the most prolific and desirable approach of haploid production. This review describes the range of techniques available for the isolation or induction of haploids by in vivo or by in vitro, estimation of haploid lavel either through chromosome counting or flowcytometry and also discourse the value of haploids.