尖孢镰孢(Fusarium oxysporum)硝酸盐营养突变株及其营养体亲和性

从荸荠、棉花、西瓜、黄瓜、胡瓜、大豆、花生等12种寄主作物上获得尖孢镰孢(F—usarium oxysporum)菌株20个,已知15个菌株分属于6个专化型。所有20个菌株在含有氯酸盐的培养基上产生抗氯酸盐的突变体,其突变体在以硝酸盐作为氮源的培养基上表现为无气生菌丝生长,即不能利用硝酸盐的突变株(nit),共获得nit突变株181个。同一专化型的nit突变株之间在以硝酸盐为氮源的培养基上配对时,在菌丝接触处可产生互补作用,即营养体亲和性,表现为旺盛气生菌丝生长。不同专化型的nit突变株之间则不能互补产生异核体而表现为非亲和性仍为突变型生长。每个菌株均获得能产生互补作用的nit突变株。根据营养体亲和性反应,20个菌株归入13个营养体亲和群(VCG),并显示出VCGs与菌株专化型之间的相关性。nit突变株在一般条件下是稳定的,而且某些nit株的亲和能力特强。

NITRATE NONUTILIZING MUTANTS OF FUSARIUM OXYSPORIUM AND THEIR VEGETATIVE COMPATIBILITY

Twenty strains of Fusarium oxysporum were collected from 12 differentkinds of hosts including Chinese waterchestnut,cotton,watermelon,cucumberetc.Among these strains,15 members belonged to 6 forma specialis accordingto virulence tests on their respective hosts,All the 20 strains produced chlo-rate-resistant sectors on PSA media amended with 1.5% KCLO_3,and nitratenonutilizing mutants(nit mutants),which were recovered by transfering thechlorate-resistant sectors to the media containing nitrate as the nitrogensource(minimal media).Complementation or vegetative compatibility testswere carried out on minimal media by pairing the nit mutants from the samestrain and from different strains.Compatible nit mutants from different stra-ins of the same forma specialis,when were paired,could generally be com-plemented on minimal media,and formed heterokaryons marked by densegrowth where their mycelia came to contact.However,those from the strainsof different forma specialis had no such reaction.On the basis of vegetativecompatibility,the 20 strains were classified to 13 vegetative compatibilitygroups(VCGs).It was also demonstrated that the correlation between VCGsand formae specialis was existed. The stability of nit mutants was demonstrated by transfering them todifferent media,and culturing them for different periods with differentconditions.The compatible abilities among some nit mutants were comparedand some highly compatible nit mutants were discovered.