Molecular breeding

About: Molecular breeding is a research topic. Over the lifetime, 2120 publications have been published within this topic receiving 56908 citations.

QTL mapping of fruit mineral contents provides new chances for molecular breeding of tomato nutritional traits

Abstract: Agronomical characterization of a RIL population for fruit mineral contents allowed for the identification of QTL controlling these fruit quality traits, flanked by co-dominant markers useful for marker-assisted breeding. Tomato quality is a multi-variant attribute directly depending on fruit chemical composition, which in turn determines the benefits of tomato consumption for human health. Commercially available tomato varieties possess limited variability in fruit quality traits. Wild species, such as Solanum pimpinellifolium, could provide different nutritional advantages and can be used for tomato breeding to improve overall fruit quality. Determining the genetic basis of the inheritance of all the traits that contribute to tomato fruit quality will increase the efficiency of the breeding program necessary to take advantage of the wild species variability. A high-density linkage map has been constructed from a recombinant inbred line (RIL) population derived from a cross between tomato Solanum lycopersicum and the wild-relative species S. pimpinellifolium. The RIL population was evaluated for fruit mineral contents during three consecutive growing seasons. The data obtained allowed for the identification of main QTL and novel epistatic interaction among QTL controlling fruit mineral contents on the basis of a multiple-environment analysis. Most of the QTL were flanked by candidate genes providing valuable information for both tomato breeding for new varieties with novel nutritional properties and the starting point to identify the genes underlying these QTL, which will help to reveal the genetic basis of tomato fruit nutritional properties.

Genetic mapping with Allele dosage information in Tetraploid Urochloa decumbens (Stapf) R. D. Webster Reveals insights into Spittlebug (Notozulia entreriana Berg) resistance

Abstract: Urochloa decumbens (Stapf) R. D. Webster is one of the most important African forage grasses in Brazilian beef production. Currently available genetic-genomic resources for this species are restricted mainly due to polyploidy and apomixis. Therefore, crucial genomic-molecular studies such as the construction of genetic maps and the mapping of quantitative trait loci (QTLs) are very challenging and consequently affect the advancement of molecular breeding. The objectives of this work were to (i) construct an integrated U. decumbens genetic map for a full-sibling progeny using GBS-based markers with allele dosage information, (ii) detect QTLs for spittlebug (Notozulia entreriana) resistance, and (iii) seek putative candidate genes involved in defense against biotic stresses. We used the Setaria viridis genome a reference to align GBS reads and selected 4,240 high-quality SNP markers with allele dosage information. Of these markers, 1,000 were distributed throughout nine homologous groups with a cumulative map length of 1,335.09 cM and an average marker density of 1.33 cM. We detected QTLs for resistance to spittlebug, an important pasture insect pest, that explained between 4.66 and 6.24% of the phenotypic variation. These QTLs are in regions containing putative candidate genes related to defense against biotic stresses. Because this is the first genetic map with SNP autotetraploid dosage data and QTL detection in U. decumbens, it will be useful for future evolutionary studies, genome assembly, and other QTL analyses in Urochloa spp. Moreover, the results might facilitate the isolation of spittlebug-related candidate genes and help clarify the mechanism of spittlebug resistance. These approaches will improve selection efficiency and accuracy in U. decumbens molecular breeding and shorten the breeding cycle.

FISH and GISH: Modern cytogenetic techniques

Abstract: In recent years, advances in the molecular cytogenetic technique of fluorescence in situ hybridization (FISH), which enables the direct chromosomal localization of labelled DNA probes and genomic in situ hybridization (GISH), which determines the inter-species distribution of repeated sequences have enabled a resurgence of cytogenetic analysis in plant genome research and molecular breeding. Practical applications of these techniques in chromosome mapping, genome analysis, determination of phylogenetic relationship, detection of chromosomal aberrations and alien chromatin in plant breeding programmes, study of chromosome organization at interphase nuclei and analysis of somaclonal variations in tissue culture have been presented.

Haploid and Doubled Haploid Techniques in Perennial Ryegrass (Lolium perenne L.) to Advance Research and Breeding

Abstract: The importance of haploid and doubled haploid (DH) techniques for basic and applied research, as well as to improve the speed of genetic gain when applied in breeding programs, cannot be overstated. They have become routine tools in several major crop species, such as maize (Zea mays L.), wheat (Triticum aestivum L.), and barley (Hordeum vulgare L.). DH techniques in perennial ryegrass (Lolium perenne L.), an important forage species, have advanced to a sufficiently successful and promising stage to merit an exploration of what their further developments may bring. The exploitation of both in vitro and in vivo haploid and DH methods to (1) purge deleterious alleles from germplasm intended for breeding; (2) develop mapping populations for genetic and genomic studies; (3) simplify haplotype mapping; (4) fix transgenes and mutations for functional gene validation and molecular breeding; and (5) hybrid cultivar development are discussed. Even with the comparatively modest budgets of those active in forage crop improvement, haploid and DH techniques can be developed into powerful tools to achieve the acceleration of the speed of genetic gain needed to meet future agricultural demands.

Role of SNPs in determining QTLs for major traits in cotton

Abstract: A single nucleotide polymorphism is the simplest form of genetic variation among individuals and can induce minor changes in phenotypic, physiological and biochemical characteristics. This polymorphism induces various mutations that alter the sequence of a gene which can lead to observed changes in amino acids. Several assays have been developed for identification and validation of these markers. Each method has its own advantages and disadvantages but genotyping by sequencing is the most common and most widely used assay. These markers are also associated with several desirable traits like yield, fibre quality, boll size and genes respond to biotic and abiotic stresses in cotton. Changes in yield related traits are of interest to plant breeders. Numerous quantitative trait loci with novel functions have been identified in cotton by using these markers. This information can be used for crop improvement through molecular breeding approaches. In this review, we discuss the identification of these markers and their effects on gene function of economically important traits in cotton.