Genetic diversity analysis in (Brassicaceae) germplasm using phenotypic Brassica juncea differences and molecular markers
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Date
2023
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DIVISION OF GENETICS ICAR-INDIAN ADRICULTURAL RESEARCH INSTITUTE NEW DELHI-110012
Abstract
The response to selection in any crop improvement program depends on the degree of
variance and heritability, and trait association. The objective of the current study was
to explain variance, heritability components, genetic diversity, correlation among the
traits, and marker trait association (MTA) in Indian mustard [
Czern & Coss] to recognize promising genotypes for effective breeding. Two hundred
Brassica juncea (L).
and eighty-nine diverse accessions of Indian mustard belonging to four continents
were analyzed for yield and yield-related traits over two seasons (2017–2018 and
2018– 2019), using an alpha lattice design with two replications. The genetic variance
was found to be significant (P ≤ 0.01) for the individual environments as well as
under pooled analysis for all of the evaluated traits. High heritability combined with
high genetic advance as percent of mean and genotypic coefficient of variation was
observed for flowering traits, plant height traits, seed size, and seed yield/plant; hence,
a better genetic gain is expected upon the selection for these traits over subsequent
generations. Both correlation and stepwise regression analysis indicated that the main
shoot length, biological yield, total seed yield, plant height up to the first primary
branch, seed size, total siliqua count, days to flowering initiation, plant height at
maturity, siliquae on the main shoot, main shoot length, and siliqua length were the
most significant contributory traits for seed yield/plant. Genetic diversity using the
phenotypic data revealed the genotypes grouped into five clusters and the most
diverse cluster was cluster II (6.29). A high inter-cluster distance (D2
) was recorded
between cluster II and cluster IV (15.68), both the clusters can be used in
hybridization breeding programs. Molecular genetic diversity of the 269 genotypes
using 101 molecular markers (89 SSRs and 12 IPs) grouped the genotypes into five
clusters. Structure analysis revealed that genotypes were grouped into two sub populations A and B, however, few genotypes had shown allele admixture
representing genes carrying from both the sub-populations. Gene diversity revealed
moderate diversity of the gene and the average number of alleles were also moderates
in range. Linkage disequilibrium of the markers defined the low LD (0.127). Marker
trait association revealed one marker (Na10A08) significantly associated with the
seed yield per plant in pooled data analysis. Out of the total 101 markers, 20 markers
were associated with the yield-related traits. IC-597867 was identified as promising
genotype from the diversity study, which was the highest yielder, which can be used
in future breeding programs for yield enhancement in Indian mustard.