Selection of Powdery Mildew Resistant Brassica Genotypes Based on Disease Indexing and Microsatellite Markers

Powdery mildew disease of oilseed mustard caused by Erysiphe cruciferarum is a primary reason of yield reduction not only in India but also throughout the world. Identification and cultivation of resistant mustard genotypes against powdery mildew is the only way to overcome this challenge. In the present investigation, we targeted to screen 75 Brassica genotypes against powdery mildew based on disease indexing under field conditions and gene-specific molecular markers. Disease reaction on both the cotyledonary and true leaves was screened with using a modified 0-9 scale score as well as with nineteen disease linked microsatellite markers. In disease indexing under field conditions, genotypes viz., L-4 and PC-5 were identified as immune, China and RP-9 were considered as highly resistant and GSC-7 and PC-6 were recognized as resistant whilst genotypes i.e., RB-50, Pusa Bold, WRR-10 and GSL-1 were accredited as moderately resistant. Molecular markers based UPGMA dendrogram classified Rohini, WRR-22, PC-6, PusaBold, China, WRR-8, GSL-1, WRR-7, RH-749, L-4 and RB-50 as highly resistant mustard genotypes. In addition, disease linked marker cnu_m616 had the highest polymorphic information content (0.75) with greatest ability to differentiate resistant genotypes from susceptible genotypes, may be employed directly in mustard breeding programmes in future.