影响大豆疫霉根腐病菌卵孢子生活力的因素

在某些大豆生产区,由大豆疫霉(Phytophthorasojae)引起的大豆根茎腐烂病是一种普遍流行的、极具破坏性的病害,病原真菌以卵孢子在土壤中越冬,在条件适宜时导致下一年大豆发生根茎腐烂。病原菌卵孢子也可以存在于患病种皮内,但其在病害循环中的作用还不清楚。卵孢子通常休眠一段时间后才萌发,这阻碍了大豆疫霉有性生殖后代毒性的遗传和变异研究。而研究的目的是寻找一种能够促进卵孢子在短时间内大量萌发的方法。在研究过程中采用MTT染色法检测处理后的卵孢子的生活力。结果表明,卵孢子龄期、预处理温度、化学物质在某种程度上均影响大豆疫霉卵孢子的生活力。用0.4%的KMnO4处理45d龄期的卵孢子,或35℃下处理5d有利于卵孢子的萌动,H2O2、大豆根汁液和大豆根际土壤浸出液对卵孢子生活力没有影响。

Factors affecting viability of oospores of Phytophthora sojae

Phytophthora root and stem rot, caused by Phytophthora sojae, is a prevalent and destructive disease in some soybean-growing regions. The causal fungus overwinters with oospores in soil and causes soybean root and stem rot next year. Oospores also exist in the diseased seed, but its real significance in the disease cycle is unknown. The oospores often remain dormant for a period of time to germinate, which confines the research of inheritance and variation behavior of the oospores. This study aims at finding a way that can promote germination of oospores in a short time and in a large number. Factors affecting viability of oospores of Phytophthora sojae were evaluated by using tetrazolium bromide. It indicated that oospore age, pretreatment temperature, chemicals can affect to some extent the viability of oospores of P. sojae. Pretreating 45 day-old oospores with KMnO4 at the concentration of 0.4% for 20 min, or with 35 ℃ for five days, favors activies of oospores, and that H2O2, soybean root extract and soybean rhizosphere soil extract have no effect on viability of oospores.