大豆疫霉菌的土壤诱集分离检测技术研究

STUDY ON ISOLATING AND DETECTING PHYTOPHTHORA SOJAE FROM SOIL WITH A BAITING METHOD

利用大豆叶片可以诱集到土壤中的大豆疫霉菌(Phytophthora sojae)。诱集前土壤在-7 ℃低温下处理10 h，诱集过程中适当加大水面与土面的距离，强日光照射1.5～4 h，可以得到被P.s侵染的大豆叶碟，杂菌污染少，该方法适于P.s的诱集分离。在预培养前对土壤进行36 ℃处理4 h，加水使土壤含水量至饱和状态，光照条件下预培养后加入感病叶片，在4000 lx光照下培养10～12 h，可以最大限度地检测出土壤内的P.s菌量。用含有对土壤中P.s有抗性基因(Rps)的大豆叶片则诱集不到P.s，或者仅能诱集到少量P.s，且P.s在叶碟上只形成不成熟的孢子囊。

Using leaf disk of soybean as bait could isolate photophthora sojae from soil. The results showed that, -7 ℃ low-temperature dealing with soil before pre-incubation for 10 hours, enlarging depth of water above the top of the soil, under sun-light baiting for 1.5～4 hours can acquire leaves pure-infected by P.s. The dealt adapt to the isolating of pathogen. Before pre-incubation dealing with soil under 36 ℃ for 4 hours, adding water to saturation, pre-incubation under light before adding susceptible leaf, keeping on cultivating under 4000 lx light for 10～12 hours could detect the most number of P.s in soil. The study also found, as baits, if leaf-disks contain resistant P.s gene(Rps), it could not bait the avirulence P.s or the baited P.s format small-type sporangia on the resistant leaf.