Advances in cereal genomics and applications in crop breeding [Erratum: 2007 Jan., v. 25, issue 1, p. 1.]

The level of cereal yields and the quality of these yields depend, to a large extent, on a crop management system, the genetic potential of a given cultivar, but also on factors that may cause damage to plants or a reduction in yield. Such factors include fungal diseases of cereals, which may cause a reduction in yield by 15–20%, and in extreme cases even by 60%. The main factors determining the occurrence of these pathogens are the weather conditions during the growing season of plants, crop rotation, the previous crop, the soil tillage system, and nitrogen fertilisation. Fungal diseases of cereals limit plant growth and development, as well as reduce grain yield and quality. This paper reviews the literature on fungal diseases of cereals.

The Most Important Fungal Diseases of Cereals—Problems and Possible Solutions

Advances in haploid production in higher plants

The genus Secale is small but very diverse. Despite the high economic importance, phylogenetic relationships of rye species have not been fully determined, and they are extremely important for the process of breeding of new cultivars that can be enriched with functional traits derived from wild rye species. The study analyzed the degree of relationship of 35 accessions of the genus Secale, representing 13 most often distinguished species and subspecies, originating from various seed collections in the world, based on the analysis of non-coding regions of the chloroplast (cpDNA) and mitochondrial genome (mtDNA), widely used in phylogenetic and population plant studies, because of a higher rate of evolution than the coding regions. There was no clear genetic structure between different species and subspecies, which may indicated the introgression between these taxa. The obtained data confirmed that S. vavilovii was very similar to S. cereale, which confirmed the assumption that they might share a common ancestor. The results also confirmed the divergence of S. sylvestre from other species and subspecies of rye. Areas that may be useful molecular markers in studies on closely related species of the genus Secale were also indicated.

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Genetic diversity and relationship between cultivated, weedy and wild rye species as revealed by chloroplast and mitochondrial DNA non-coding regions analysis.

Secale L. is a small but important genus that includes cultivated rye. Although genetic diversity of cultivated rye is high, patterns of genetic diversity in the whole genus, and potential factors affecting the distribution of genetic diversity remain elusive. The population structure and distribution of genetic variation within Secale, and its correlation with taxonomic delimitation, cultivation status or spatial distribution in relation to geography and climate zones were analyzed in this study. A collection of 726 individual plants derived from 139 different accessions representing Secale cereale, S. vavilovii, S. strictum, and S. sylvestre were investigated using SSR analysis and sequence diversity analysis of a nuclear EST region. Our results indicated that perennial S. strictum subspecies are genetically divergent from annual forms of the genus. Existence of two distinct clusters within the annual taxa was observed, one corresponding to samples from Asia, and a second to those outside of Asia. No clear genetic structure was observed between different annual species/subspecies, indicating introgression between these taxa. The analysis of cultivated rye revealed that landrace populations from the Middle East have the highest genetic diversity, supporting the idea of the area being the center of origin for cultivated rye. Considering high adaptive potential of those populations, Middle Eastern landraces should be regarded as genetic resources reservoirs for new niches and future breeding programs.

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Phylogeny and genetic structure in the genus Secale.

Association mapping is a powerful approach to detect associations between traits of interest and genetic markers based on linkage disequilibrium in molecular plant breeding. The aim of this study was the identification of single nucleotide polymorphisms (SNPs) and SilicoDArT markers associated with yield traits and morphological features in maize. Plant material constituted inbred lines. The field experiment with inbred lines was established on 10 m2 plots in a set of complete random blocks in three replicates. We observed 22 quantitative traits. Association mapping was performed in this study using a method based on the mixed linear model with the population structure estimated by eigenanalysis (principal component analysis applied to all markers) and modeled by random effects. As a result of mapping, 969 markers (346 SNPs and 623 SilocoDArT) were selected from 49,911 identified polymorphic molecular markers, which were significantly associated with the analyzed morphological features and yield structure traits. Markers associated with five or six traits were selected during further analyses, including SilicoDArT 4591115 (anthocyanin coloration of anthers, length of main axis above the highest lateral branch, cob length, number of grains per cob, weight of fresh grains per cob and weight of fresh grains per cob at 15% moisture), SilicoDArT 7059939 (anthocyanin coloration of glumes of cob, time of anthesis—50% of flowering plants, time of silk emergence—50% of flowering plants, anthocyanin coloration of anthers and cob diameter), SilicoDArT 5587991 (anthocyanin coloration of glumes of cob, time of anthesis—50% of flowering plants, anthocyanin coloration of anthers, curvature of lateral branches and number of rows of grain). The two genetic similarity dendrograms between the inbred lines were constructed based on all significant SNPs and SilicoDArT markers. On both dendrograms lines clustered according to the kernel structure (flint, dent) and origin. The selected markers may be useful in predicting hybrid formulas in a heterosis culture. The present study demonstrated that molecular SNP and Silico DArT markers could be used in this species to group lines in terms of origin and lines with incomplete origin data. They can also be useful in maize in predicting the hybrid formula and can find applications in the selection of parental components for heterosis crossings.

Identification of Markers Associated with Yield Traits and Morphological Features in Maize (Zea mays L.).

There are many reports describing chromosome structure, organization and evolution within goatgrasses (Aegilops spp.). Chromosome banding and fluorescence in situ hybridization techniques are main methods used to identify Aegilops Linnaeus, 1753 chromosomes. These data have essential value considering the close genetic and genomic relationship of goatgrasses with wheat (Triticumaestivum Linnaeus, 1753) and triticale (× Triticosecale Wittmack, 1899). A key question is whether those protocols are useful and effective for tracking Aegilops chromosomes or chromosome segments in genetic background of cultivated cereals. This article is a review of scientific reports describing chromosome identification methods, which were applied for development of prebreeding plant material and for transfer of desirable traits into Triticum Linnaeus, 1753 cultivated species. Moreover, this paper is a resume of the most efficient cytomolecular markers, which can be used to follow the introgression of Aegilops chromatin during the breeding process.

https://compcytogen.pensoft.net/article/30673/download/pdf/

Cytological markers used for identification and transfer of Aegilops spp. chromatin carrying valuable genes into cultivated forms of Triticum.

Abstract Breeding work using European rye populations has resulted in a considerable reduction of genetic variation in breeding materials of that species. Many taxa from the genus Secale may constitute a potential source of genetic variation in rye breeding. A source of new genetic variation can be found in such species as Secale montanum and Secale vavilovii, which are sources of resistance to fusarium ear blight and septoria leaf blotch, while Secale vavilovii may also be a source of sterilising cytoplasm. The aim of this study was to assess the efficiency of crossing the wild species Secale vavilovii and the rye subspecies Secale cereale subsp. afghanicum, Secale cereale subsp. ancestrale, Secale cereale subsp. dighoricum, Secale cereale subsp. segetale with the crop species Secale cereale ssp. cereale, and to produce F1 hybrids and describe selected morphological traits. Observations of biometric traits indicate that the F1 crosses produced may be potential sources of variation for common rye. The greatest variation in terms of all analysed phenotypic traits combined was found for the cross combinations S. c. ssp. cereale cv. Amilo × S. c. ssp. ancestrale and S. c. ssp. cereale cv. Dańkowskie Diament × S. c. ssp. dighoricum. The hybrids showed considerable variation in the analysed biometric traits within individual cross combinations.

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Biometric characteristics of interspecific hybrids in the genus Secale

The aim of this research was to analyze genetic polymorphism between nine wild species and three cultivars of rye (genus Secale L.). The genetic polymorphism was assessed by means of the RAPD method (random amplified polymorphic DNA). The coefficients of genetic similarity between the species were calculated on the basis of amplified products and they were presented in a dendrogram. The highest genetic similarity was found between the Secale cereale ‘Amilo’ and S. cereale ssp. ancestrale ecotype 30226 (70%), whereas the lowest genetic similarity was observed between S. sylvestre and S. cereale ssp. dighoricum (33%). The results indicate considerable usefulness of the wild species for crossbreeding with the cultivars of the genus Secale and as genetic resources for breeding programs.

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The genetic polymorphism between the wild species and cultivars of rye Secale cereale L.

Among all cereals, common wheat (Triticum aestivum L.) occupies the largest area of crops worldwide. Wheat leaf rust, caused by the pathogen Puccinia recondita f. sp. tritici considerably reduces the yield of wheat. Breeding for resistance combined with selection based on molecular markers may become an effective tool in the struggle against fungal diseases. Lr19 is the gene that carries high resistance to wheat leaf rust. In recent years, we have seen the development of many molecular markers in close neighbourhood of the Lr19 gene, e.g., SCS265, SCS253, GB, Xwmc221, XustSSR2001-7DL, Xgwm37 and Xgwm44. The aim of the study was to investigate the functionality of molecular markers related to the Lr19 gene. The study was based on two reference genotypes with the Lr19 gene (‘Agatha’ and Lr19) and three lines strongly infested by wheat leaf rust. Seven molecular markers were analysed, but only two of them (GB and Xwmc221) proved to be specific to the gene under study. These markers were used for analysis of 25 wheat genotypes, which were evaluated for leaf rust resistance in field conditions to confirm their usefulness for selection of breeding material. These findings point to the need of continuous search for functional molecular markers giving repeatable and

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Sylwia Mikołajczyk

Papers

Identification of Markers Associated with Yield Traits and Morphological Features in Maize (Zea mays L.).

Cytological markers used for identification and transfer of Aegilops spp. chromatin carrying valuable genes into cultivated forms of Triticum.

Biometric characteristics of interspecific hybrids in the genus Secale

The genetic polymorphism between the wild species and cultivars of rye Secale cereale L.

An analysis of the functionality of molecular markers related to the Lr19 gene conditioning resistance to wheat leaf rust.