【摘要】 根据在 0 5、1 4、5 0、10 0 μg ml等不同浓度的含药PSA平板上能否生长 ,将玉蜀黍赤霉田间菌株对多菌灵的敏感性划分为 :敏感 (S)、中抗 (MR)和高抗 (HR)等 3个水平 ,其中S菌株在 0 5 μg ml浓度下能生长 ,但在≥ 1 4μg ml浓度下生长受到完全抑制 ;R菌株在 1 4 μg ml浓度下能快速生长 ,在 5 0 μg ml浓度下能缓慢生长 ,但在≥ 10 0μg ml浓度下不能生长 ;HR在≥ 10 0 μg ml浓度下仍能生长。没有发现在 1 4 μg ml浓度下能快速生长 ,而在 5 0 μg ml浓度下能被完全抑制的田间抗性菌株。从 2 5个敏感菌株和 31个抗性菌株中随机挑选了 2个S、3个MR和 1个HR ,并以硝酸盐营养缺陷型突变体 (nit)作为另一个遗传标记 ,按照S×S、MR×MR、MR×S、HR×S、HR×MR等共设计了 7个杂交组合 ,对各杂交后代对多菌灵的敏感性测试发现 ,在所有杂交后代中均未出现除双亲表现型以外的重组型个体 ,MR×S、HR×S及HR×MR的杂交后代出现了 1∶1的分离比例。以上结果表明玉蜀黍赤霉田间菌株对多菌灵的抗药性是由单个孟德尔基因控制的 ,该基因发生不同点突变或同一点的不同等位基因发生突变可导致不同的抗性水平 ,抗药性不受修饰基因或胞质遗传因子的影响。更多还原

【Abstract】 According to the ability of the field isolates of Gibberella zeae to grow on the PSA with varying carbendazim(MBC)concentrations,three sensitivity levels of isolates were determined in vitro.The sensitive isolates(S)could grow at 0.5 μg/ml,but were completely inhibited at 1.4 μg/ml.The moderate resistant isolates(MR)could grow fast at 1.4 μg/ml and slow at 50 μg/ml,but could not grow at 100 μg/ml.The high resistant isolates(HR)could grow faster than R at 50 μg/ml,and also could grow at 100 μg/ml.No low resistant isolates,that could grow fast at 1.4 μg/ml but could not grow at 50 μg/ml,were found among the field isolates.The genetics of resistance to carbendazim in G.zeae was investigated by analyzing the sensitivity of sexual outcrossed progeny to MBC.The nitrate non-utilizing mutant (nit) as an another added genetic marker was used to select the out-crossed perithecium from self-crossed perithecia.Seven crosses were tested in all,including cross between S×S,MR×S,MR×MR,HR×S,as well as HR×MR.The results showed that no recombinant phenotype was found among all progeny of seven crosses.Progeny segregation of crosses between the parents with different sensitive levels(i.e.MR×S,HR×S,HR×MR)clearly fit a 1∶1 ratio of two parental phenotypes,and no segregation was found in the crosses of S×S and MR×MR.So it can be concluded that the two levels of MBC resistance in G.zeae are confered by two loci mutations or one locus with different allelic mutations that constitute a polymorphic series in a single Mendelian gene.In these isolates,the MBC resistance is not affected by modifying genes or cytoplasmic components.更多还原