瓜类尖孢镰刀菌的营养体亲和群研究

 应用营养亲和性方法研究了尖孢镰刀菌菌株抗氯酸盐突变体和nit突变体的诱发规律及分布特性,以及菌株营养体亲和群(VCG)的划分。研究表明,不同寄主(黄瓜、甜瓜和西瓜)分离的尖孢镰刀菌菌株形成的抗氯酸盐突变体数目差异不显著,平均为每个接种点产生0.89~0.98个;但寄主不同部位(根部、茎基部和茎中部)分离的菌株间差异显著,形成的数目分别为1.27、0.75及0.76个。菌株产生的nit1突变体比例(75.40%)显著高于nitM突变体比例(13.17%);nit1突变体数目会因菌株的寄主及菌株寄主部位的不同而有差异,寄主为黄瓜、甜瓜和西瓜的菌株产生的比例依次为67.73%、83.71%和77.50%,根部、茎基部及茎中部分离菌株产生的比例依次为81.82%、78.48%和68.64%,而在致病菌株与非致病菌株间无显著差异,分别为74.43%和79.63%;nitM突变体数目受菌株寄主影响较小,所占比例在11.17%~13.92%之间;而在寄主不同部位分离的菌株及致病菌株与非致病菌株间差异显著,分离自茎基部的菌株所占比例最高为15.97%,茎中部菌株所占比例最低为9.87%,致病菌株与非致病菌株所占比例分别为14.08%和9.26%。供试菌株分为7个VCGs,其特点为来源于不同寄主的尖孢镰刀菌菌株互不亲和,同一寄主的致病菌株与非致病菌株均不亲和,同一寄主不同部位分离的菌株可亲和。

Vegetative compatibility groups of Fusarium oxysporum strains from cucumber, melon and watermelon

Twenty strains of Fusarium oxysporum isolated from cucumber,melon and watermelon were grouped into vegetative compatibility groups(VCGs)by using nitrate nonutilizing(nit)mutants,and dif-ferent percentages of chlorate resistant mutant and nit mutant obtained from different hosts,positions of the plant and pathogenicity were observed.The results showed that the numbers of chlorate resistant mutants in each inoculation of the strains isolated from different hosts were in the range of 0.89-0.98,which were not significantly different;but it of the strains isolated from root,basal stem and middle stem were 1.27,0.75 and 0.76,respectively,which were quite different.The percentages of nit1 mutants(75.40%)were evidently higher than those of nitM mutants(13.17%).Significant differences were found among the percentages of nit1 mutants of the strains isolated from different hosts or positions of the plant,whereas slightly differences between pathogenic and nonpathogenic strains.The percentages of nit1 mutant from cucumber,melon and watermelon were 67.73%,83.71% and 77.50%,or from the root,basal stem and middle stem were 81.82%,78.48% and 68.64%,respectively.Similar situation was observed for nitM mutants in the strains from different positions of the plant and pathogenicity,but slight difference in the strains from different hosts.The highest percentage of nitM mutants occurred from the basal stem(15.97%)while the lowest from the middle stem(9.87%),and the percentages from the pathogenic and nonpathogenic strain were 14.08% and 9.26%.All isolates were grouped into seven VCGs.Strains from different hosts fell into different VCGs,nonpathogenic strains were uncompatible to pathogenic ones and vegetative compatibility was found in all strains from the different positions of the plant.