Yuan Shan-Kui, Zhou Ming-Guo
Department of Pesticide Science, Nanjing Agricultural University, Nanjing 210095, China.
Yi Chuan Xue Bao. 2003 May;30(5):474-8.
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 microgram/ml, but were completely inhibited at 1.4 micrograms/ml. The moderate resistant isolates (MR) could grow fast at 1.4 micrograms/ml and slow at 50 micrograms/ml, but could not grow at 100 micrograms/ml. The high resistant isolates(HR) could grow faster than R at 50 micrograms/ml, and also could grow at 100 micrograms/ml. No low resistant isolates, that could grow fast at 1.4 micrograms/ml but could not grow at 50 micrograms/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 x S, MR x S, MR x MR, HR x S, as well as HR x 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 x S, HR x S, HR x MR) clearly fit a 1:1 ratio of two parental phenotypes, and no segregation was found in the crosses of S x S and MR x MR. So it can be concluded that the two levels of MBC resistance in G. zeae are conferred 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.
根据玉米赤霉病菌田间分离菌株在含有不同多菌灵（MBC）浓度的马铃薯蔗糖琼脂（PSA）培养基上的生长能力，在体外确定了三种敏感性水平的分离菌株。敏感菌株（S）在0.5微克/毫升时能够生长，但在1.4微克/毫升时完全被抑制。中度抗性菌株（MR）在1.4微克/毫升时能够快速生长，在50微克/毫升时生长缓慢，但在100微克/毫升时不能生长。高抗性菌株（HR）在50微克/毫升时比MR生长得更快，并且在100微克/毫升时也能生长。在田间分离菌株中未发现低抗性菌株，即那些在1.4微克/毫升时能够快速生长但在50微克/毫升时不能生长的菌株。通过分析有性杂交后代对MBC的敏感性，研究了玉米赤霉病菌对多菌灵的抗性遗传。利用硝酸盐不利用突变体（nit）作为另一个附加的遗传标记，从自交子囊中选择杂交子囊。总共测试了七个杂交组合，包括S×S杂交、MR×S杂交、MR×MR杂交、HR×S杂交以及HR×MR杂交。结果表明，在七个杂交组合的所有后代中均未发现重组表型。不同敏感性水平亲本之间杂交（即MR×S、HR×S、HR×MR）的后代分离明显符合两种亲本表型1:1的比例，而在S×S和MR×MR杂交中未发现分离现象。因此可以得出结论，玉米赤霉病菌对MBC的两种抗性水平是由两个位点的突变或一个位点的不同等位基因突变所赋予，并在单个孟德尔基因中构成一个多态系列。在这些分离菌株中，MBC抗性不受修饰基因或细胞质成分的影响。
