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我们在研究用鲁保一号(Gleosporium sp.)防治菟丝子时,发现这种真菌很不稳定。从严重发病的菟丝子上分离到的菌株,经多代培养后,菌落由桔红转为黄绿,逐渐产生气生菌丝,孢子不整齐,发芽率低,产孢量下降,致病力降低,甚至完全丧失生产使用价值。经试验发现并证明,这种真菌经培养多代后,由于一些核产生突变。就形成了由亲代类型(Ⅰ型)和突变类型(Ⅱ型)两种类型核组成的菌株。在传代过程中,同一菌株中这两种核的比例很不稳定,致病力低的突变类型核有逐渐上升的趋势,这是鲁保一号菌种退化的主要原因。实验结果如下。
When we studied the prevention and treatment of dodder with Gleosporium sp., We found that the fungus was very unstable. After many generations of strains isolated from the dodder severely affected, the colonies turned from orange to yellow-green, and gradually produced aerial hyphae with irregular spores, low germination rate, decreased sporulation and decreased pathogenicity , Or even completely lost the value of production and use. The experiment found and proved that this kind of fungi cultured for many generations, due to some nuclear mutations. A strain of both parental type (type I) and mutant type (type II) was formed. During the passage, the proportion of these two nuclei in the same strain was very unstable, and the mutation type with low virulence tended to increase gradually, which was the main reason for the degeneration of strain Lu-Bu No.1. The experimental results are as follows.