Morphological characterization and molecular diversity assessment of rust resistant genetic stocks of wheat

Wheat (Triticum spp.) is a global staple food crop, contributing significantly to the world's food security. Understanding and harnessing the genetic diversity within wheat cultivars is paramount for developing resilient and high-yielding varieties. The present study reports rust response of 31 registered rust resistant genetic stocks of wheat against recently identified and most virulent pathotypes of all three rust pathogens and their morphological and molecular diversity assessment. Analysis of variance (ANOVA) showed indicated significant differences among the genotypes for all the studied traits. Among 31 genetic stocks 30, 15, and 8 were found resistant against all the tested pathotypes of stem, leaf and stripe rust pathogens, respectively, whereas only two (FLW21 and FLW28) conferred resistance against all three rusts. Molecular profiling with 59 polymorphic SSRs resulted in 194 alleles with an average 3 alleles/loci. With an average of 0.54, the Polymorphism Information Content (PIC) varied from 0.34 to 0.75, reflecting higher allelic variation. The average gene diversity, heterozygosity, major allele frequency, and minor allele frequency were 0.61, 0.31, 0.48, and 0.52, respectively. Cluster analysis grouped 31 genetic stocks into 3 clusters. The AMOVA revealed that within population variation was higher than between them (76% vs. 24%). Clustering was  further supported by the structure and Principal Coordinate Analysis (PCoA). Structure analysis grouped the genetic stocks into three sub-populations. These findings will help in suggesting different cross combinations for wheat rust resistance breeding and pyramiding of multiple rust resistance genes.