贵州省烟草赤星病菌对啶酰菌胺的敏感性基线

对2014—2015年采自贵州省田间未使用过琥珀酸脱氢酶抑制剂 (SDHIs) 的烟草赤星病病样进行了病原菌分离和鉴定，并采用菌丝生长速率法建立了烟草赤星病菌群体对啶酰菌胺的敏感性基线。结果表明:虽然烟草赤星病菌不同菌株在菌落、孢子形态和致病性上有较大差异，但均属于交链格孢Alternaria alternata。啶酰菌胺抑制赤星病菌群体 (n = 102) 菌丝生长的EC₅₀值在0.186~5.818 μg/mL之间，平均EC₅₀值为 (2.157 ± 1.112) μg/mL，不同敏感性菌株频率分布为连续的单峰曲线，该平均EC₅₀值可以作为烟草赤星病菌对啶酰菌胺的敏感性基线。进一步研究表明，贵州省烟草赤星病菌的Sdh B基因在第209位、277位和224位等密码子存在核苷酸多样性，但未发现这种多样性与烟草赤星病菌对啶酰菌胺的敏感性之间存在关联。

Sensitivity baseline to boscalid of Alternaria alternata causing tobacco brown spot in Guizhou Province

The pathogenic fungus causing tobacco brown spot in Guizhou Province was isolated and identified from diseased samples collected during 2014 to 2015, which have never been treated with succinate dehydrogenase inhibitors(SDHIs), and their sensitivity baseline to boscalid was established by mycelial growth rate tests. The results suggested that there were significant differences in colony and conidium morphlogy, and pathogencicity among these isolates. However, all isolates were identified as Alternaria alternata. In addition, the EC₅₀ values of boscalid inhibiting the growth of A. alternata population (n = 102) from tobacco fitted unimodal distribution and varied from 0.186 to 5.818 μg/mL with the mean value of (2.157 ± 1.112) μg/mL, which could be adopted as the baseline sensitivity of A. alternata on tobacco to boscalid and used for monitoring the sensitivity shift in future. Further study indicated that there was some nucleotide polymorphism in codons, such as 209, 277 and 224 in Sdh B of A. alternata. However, no relationship was observed between this nucleotide diversity and the sensitivity to boscalid in A. alternata causing tobacco brown spot.