Molecular identification and pathogenic variability in F2 generation of Cochliobolus sativus

Spot blotch is an alarming disease for wheat, hence it’s already known that the disease is 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 exist or not 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 percent disease index were studied to understand the pathogenic variability. All components of disease development showed positive co-efficient relation with each other disease development components. Non-significant relationships were observed between necrosis and secondary spore production, disease index and percent disease index. Cumulatively infection frequency and lesion size create 77.95% variation. According to percent 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.

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