球孢白僵菌种群野生菌株异核现象的分子验证*

球孢白僵菌28S rRNA基因D11域由于一内含子的存在与否,引起这一区域的扩增产物有两种片段类型(约520bp及120bp),将此作为分子标记分析了球孢白僵菌的117个菌株,发现17%菌株的扩增产物为双片段类型,即为异核体。异核体在不同种群中的分布频率因地理生态条件而异。单孢分离分析表明,异核体的分离频率约为35%。RAPD检测结果说明异核体在准性循环中发生了不同程度的遗传交换及遗传重组。球孢白僵菌异核体在继代培养中极不稳定。

MOLECULAR IDENTIFICATION OF HETEROKARYOSIS IN POPULATION OF WILD TYPE ISOLATES OF BEAUVERIA BASSIANA

Due to the presence/absence of an intron at domain D11 of 28S rRNA gene of Beauveria bassiana, the PCR product sizes of this region had two patterns amongst different strains (ca. 520bp and 120bp). Taken it as molecular marker, 117 wild type isolates were analyzed and 17% of them were found to show double band type, i.e. heterokaryons. Population investigations indicated that the heterokaryotic frequencies varied greatly associated with different geographical and ecological habitats. Single spore isolation analysis indicated that 35% genotypic segregation was obtained from heterokaryotic strain. RAPD analysis of representative segregants suggested that genetic exchange and recombination occurred during heterokaryon parasexual cycling. High level of genetic instability was also found during subculturing of heterokaryotic strains through saprophytic media.