Genome-wide association mapping for Fe, Zn and yield traits in pigeonpea
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Date
2021
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Punjab Agricultural University, Ludhiana
Abstract
In the present study, an effort was made to understand the complex nature of yield and quality traits and genome-wide association studies (GWAS) was undertaken to identify QTLs associated with traits. The analysis of variance (ANOVA) revealed significant variation among all genotypes in both the years and pooled data. Measurement of skewness and kurtosis indicated presence of duplicate and complementary gene interaction for different traits. The seed yield exhibited highly positive and significant correlation with number of primary branches per plant, number of secondary branches per plant and number of pods per plant for both the years and pooled data across two years. Path analysis identified pods per plant, number of primary and secondary branches as the major contributing traits to grain yield in both the years and pooled data. Yield per plot and pods per plant exhibited high heritability along with high genetic advance showing additive gene effect and could be considered during selection. In genotypic analysis, a total of 7366 filtered SNPs were used for genome-wide association studies through ddRAD-Seq. A total of 30 highly significant associated SNPs in 2018-19, 23 significant associated SNPs in 2019-20 and 25 significant associated SNPs in pooled data were identified through combination of two or more than two models for different traits. Most of the SNP loci were found to be environment and trait specific but few stable and consistent SNPs were identified. Some of the SNPs associated with days to maturity, yield per plot and grain iron content were observed to be consistent in 2018-19 and pooled conditions. The candidate regions were defined by the average LD decay distance or the LD block. Biological function of the identified candidate genes revealed their role in plant growth and development, organogenesis, pollen development and source-sink relationship. These genes were found to be present on chromosome 02, 03 and 09. Three polymorphic KASP markers for traits viz., grain iron content, number of primary branches and yield per plot were validated and showed that parents have homozygous alleles for the traits and alleles were found to be segregating in the F2:3 population. Promising genotypes for grain iron, grain zinc content and yield attributing traits were identified which can be used as donor parents in pigeonpea breeding programme and developed markers can be used in marker assisted selection (MAS) for identifying desirable genotypes having allele of interest.
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Harpreet Kaur (2021). Genome-wide association mapping for Fe, Zn and yield traits in pigeonpea (Unpublished Ph.D. Dissertation). Punjab Agricultural University, Ludhiana, Punjab, India.