Screening of Alternaria Blight Resistant Linseed (Linum usitatissimum) Genotypes Based on Disease Indexing and Gene Specific SSR Markers

In present investigation, disease scoring and SSR-based molecular analysis of 92 linseed genotypes was performed against Alternaria blight resistant line (s) identification. Total 20 markers were used for the study out of which only seven markers showed polymorphism between the resistant and non-resistant lines. A total of 24 alleles were identified with an average of 3.4 alleles per locus for polymorphic SSR markers. The Polymorphic Information Content (PIC) values varied between 0.530-0.662 (Lu_899 to LuC_8166563_1) with an average of 0.60. The primer which showed highest PIC values was LuC_8166563_1 while the lowest was observed for the primer Lu_899. The major allele frequency varied between 0.32 (LUSc_270_01, LU_934, LuC_8166563_1) to 0.54 (Lu_899) with a mean value of 0.40. Population structure analysis revealed that 29 genotypes were assigned to group1 (G1), 33 genotypes to G2 and 30 genotypes were assigned to admixture group G3. The relationship between groups derived from STRUCTURE explained that G1 and G2 comprised of distinct types. The present investigation has helped in differentiating the genotype based on their resistance for the disease. Six genotypes viz., LMS-2015-42, LMS-2014-20, IC0498675, IC0498724, IC0498761 and IC0424878 were identified as highly resistant. While genotypes including IC0525920, IC0498538, IC0498768, IC0526514, IC0305053, IC0385383, and IC0499156 were considered as resistance. Twenty-one were found to be moderately resistant to disease while forty-two moderately susceptible and sixteen susceptible.