Molecular identification and pathogenic variability in F2 generation of Cochliobolus sativus

Abstract

Spot blotch is an alarming disease for wheat caused by the anamorphic stage (Bipolaris sorokiniana) generally but it’s rare when it caused by telomorphic stage (Cochliobolus sativus). The present study reveals molecular identification and pathogenic variability among the isolates of C. sativus in F2 generation. Each of the C. sativus (F2 generation) isolates was identified and confirmed following ITS rDNA sequence analysis. Internal transcribed spacers (ITS) region sequence reference was KC311473.1and EF452447.1. For determining pathogenic variability a susceptible wheat cultivar “Kanchan” was used. Seven components of disease development like infection frequency, lesion size, lesion cover, necrosis, secondary spore production, disease severity and per cent disease index were studied to understand the pathogenic variability. All components of disease development showed positive co-efficient relation with each other. Non-significant relationships were observed between necrosis and secondary spore production, disease index and per cent disease index. Cumulatively infection frequency and lesion size showed 77.95% variation. According to per cent disease index and secondary spore production isolate CSF2-32 and CSF2-58 were most virulent and aggressive ones among the tested isolates. A cluster analysis indicated that the isolates exhibited distinct differential virulence patterns with five groups supported by a dendrogram figure.