Morphological, pathological and genetic variations among isolates of Cochliobolus sativus from Nepal

作者：Mahto Baidya N; Gurung Suraj; Nepal Achala; Adhikari Tika B^*

来源：European Journal of Plant Pathology, 2012, 133(2): 405-417.

DOI：10.1007/s10658-011-9914-z

• Bipolaris sorokiniana
• Population genetics
• Triticum aestivum
• Virulence

Spot blotch, caused by Cochliobolus sativus (Ito %26 Kuribayashi) Drechs. ex Dastur, is one of the important diseases of wheat worldwide. The main objective of this study was to investigate the phenotypic and genotypic variability among C. sativus isolates from the hills and plains in Nepal. A total of 48 monoconidial isolates of C. sativus from the hills (n = 24 isolates) and plains (n = 24 isolates) in Nepal were analyzed for morphology, aggressiveness and genetic structure. C. sativus isolates were grouped into three categories on the basis of their colony texture and mycelia colour. Thirteen isolates from the hills and plains belonging to three morphological groups were randomly selected and evaluated for aggressiveness on eight wheat cultivars (Chirya 1, Chirya 7, Milan/Shanghai 7, SW 89-5422, PBW 343, BL 1473, BL 3036, and RR 21) at the seedling stage. Nonparametric analysis revealed that the isolates from the plains (median disease rating of 5) were significantly (P = 0.0001) more aggressive than the isolates from the hills (median disease rating of 3). A significant (P = 0.0001) isolate by cultivar interaction was demonstrated and the isolates from the same geographic region and morphological group displayed different degrees of aggressiveness on wheat cultivars tested. Combined IS-PCR and rep-PCR analyses revealed moderate gene diversity (H = 0.24 and 0.25 for the hills and plains, respectively). Low linkage disequilibrium (LD) value and non-significant (P = 0.001) population differentiation (GaEuro(ST)(3) = 0.05) were detected, indicating that isolates of C. sativus from the hills and plains in Nepal were genetically similar. Analysis of molecular variation (AMOVA) revealed low (7%) levels of genetic variation between the hill and plain populations, whereas %26gt; 93% of genetic variation was found within populations. Overall, C. sativus isolates from Nepal are pathologically and genetically diverse, and such information will be useful in developing wheat cultivars resistant to C. sativus.

• 出版日期2012-6