Molecular breeding

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

QTLomics in Soybean: A Way Forward for Translational Genomics and Breeding

Abstract: Food legumes play an important role in attaining both food and nutritional security along with sustainable agricultural production for the well-being of humans globally. The various traits of economic importance in legume crops are complex and quantitative in nature, which are governed by quantitative trait loci (QTLs). Mapping of quantitative traits is a tedious and costly process, however, a large number of QTLs has been mapped in soybean for various traits albeit their utilization in breeding programmes is poorly reported. For their effective use in breeding programme it is imperative to narrow down the confidence interval of QTLs, to identify the underlying genes, and most importantly allelic characterization of these genes for identifying superior variants. In the field of functional genomics, especially in the identification and characterization of gene responsible for quantitative traits, soybean is far ahead from other legume crops. The availability of genic information about quantitative traits is more significant because it is easy and effective to identify homologs than identifying shared syntenic regions in other crop species. In soybean, genes underlying QTLs have been identified and functionally characterized for phosphorous efficiency, flowering and maturity, pod dehiscence, hard-seededness, α-Tocopherol content, soybean cyst nematode, sudden death syndrome, and salt tolerance. Candidate genes have also been identified for many other quantitative traits for which functional validation is required. Using the sequence information of identified genes from soybean, comparative genomic analysis of homologs in other legume crops could discover novel structural variants and useful alleles for functional marker development. The functional markers may be very useful for molecular breeding in soybean and harnessing benefit of translational research from soybean to other leguminous crops. Thus, soybean crop can act as a model crop for translational genomics and breeding of quantitative traits in legume crops. In this review, we summarize current status of identification and characterization of genes underlying QTLs for various quantitative traits in soybean and their significance in translational genomics and breeding of other legume crops.

Breeding and genetics.

Abstract: Three complete diallel crosses using purebred bucks and does of four rabbit breeds (Californian, C; Chinchilla, Ch; New Zealand White, N and Semigiant White, S) were realized in different periods (1968-1970 and 2003-2004), involving 6293 preweaning records. The traits studied were: total born (TBorn), born alive (BornA), viability at birth (ViabB), number weaned (NW), proportion of weaned litters (PWL) and viability at weaning (ViabW). A generalized linear mixed model using the PROC GLMMIX of SAS was applied, which considered the fixed effects of breed of the doe and the buck (4 classes each), experiment (3 trials), doble and triple interactions between all fixed effects, and the random effect of parity (5 levels).The does from breeds S and N excelled the others in viabilities and NW, while the bucks from N breed showed disadvantages in viabilities. The interaction effect between the doe and buck breeds identified the best crosses for NW, as SN, SCh and CS, over NCh, and C. The dam and sire breeds*experiment interactions were significant for ViabB, NW and ViabW. Differences between the breed of the doe were only found in experiment 1 and 2 with advantages for the N doe breed. The effect of buck breed was only significant in experiment 2, for ViabB, where C excelled N, and in ViabW the S breed excelled the rest. The triple interaction was significant in ViabW. It showed the best correspondence in merit order between experiment 1 and 3 with correlations of 0.5. The best three crosses across experiments were: SN, ChS, and ChN, which, along with the CS cross and the S and N dam breeds are recommended for commercial crossbreeding schemes.

Association Mapping for 24 Traits Related to Protein Content, Gluten Strength, Color, Cooking, and Milling Quality Using Balanced and Unbalanced Data in Durum Wheat [Triticum turgidum L. var. durum (Desf).].

Abstract: Durum wheat [Triticum durum (Desf)] is mostly used to produce pasta, couscous, and bulgur The quality of the grain and end-use products determine its market value However, quality tests are highly resource intensive and almost impossible to conduct in the early generations in the breeding program Modern genomics-based tools provide an excellent opportunity to genetically dissect complex quality traits to expedite cultivar development using molecular breeding approaches This study used a panel of 243 cultivars and advanced breeding lines developed during the last 20 years to identify SNPs associated with 24 traits related to nutritional value and quality Genome-wide association study (GWAS) identified a total of 179 marker-trait associations (MTAs), located in 95 genomic regions belonging to all 14 durum wheat chromosomes Major and stable QTLs were identified for gluten strength on chromosomes 1A and 1B, and for PPO activity on chromosomes 1A, 2B, 3A, and 3B As a large amount of unbalance phenotypic data are generated every year on advanced lines in all the breeding programs, the applicability of such a dataset for identification of MTAs remains unclear We observed that ∼84% of the MTAs identified using a historic unbalanced dataset (belonging to a total of 80 environments collected over a period of 16 years) were also identified in a balanced dataset This suggests the suitability of historic unbalanced phenotypic data to identify beneficial MTAs to facilitate local-knowledge-based breeding In addition to providing extensive knowledge about the genetics of quality traits, association mapping identified several candidate markers to assist durum wheat quality improvement through molecular breeding The molecular markers associated with important traits could be extremely useful in the development of improved quality durum wheat cultivars using marker-assisted selection (MAS)