不同pH水平下两种菌根真菌对紫云英生长的影响及其相互作用

The interaction and effect of two species of arbuscular mycorrhizal fungi on the growth of Astragalus sinicus L. at different pH level

设计在不同pH水平(4.3、5.1、5.8、6.8)下两种VA菌根真菌Glomus mosseae和Gigaspora margarita对紫云英Astragalus sinicus进行单接种、混合接种及无接种对照的盆栽实验。对紫云英地上和地下部分生物量、根部侵染率、SDH和ALP酶活进行了检测。实验结果表明:紫云英的生长效应与VA菌根真菌的侵染率及两种酶活成明显相关性。土壤pH升高,单接种Glomus mosseae和混合接种的侵染率也随之升高,而单接种Gigaspora margarita的侵染率呈现出先上升后下降的趋势。本实验设计了特异性扩增Glomus mosseae和Gigaspora margarita的引物gm1和gig1,在混合接种实验中,nested PCR扩增结果显示:在低pH水平下(4.3-5.1)大多数根段为Gigaspora margarita所侵染,在高pH水平下(5.8-6.8)Glomus mosseae表现出较强的竞争力,但并没有检测到两种VA真菌存在于同一条侵染根段;对比单接种实验,在低pH水平下,Glomus mosseae显著抑制了Gigaspora margarita的侵染,而在高pH水平下Gigaspora margarita明显促进Glomus mosseae的侵染。

The effects of two species of arbuscular mycorrhizal fungi, Glomus mosseae and Gigaspora margarita to Astragalus sinicus biomass under the condition of four pH level ranging from acidic to neutral （4.3, 5.1, 5.8 and 6.8） were investigated in a pot experiment. Some important parameters reflecting the colonization rate of AMF were tested, including TB coloration, the enzyme activity of succinate dehydrogenase （SDH） and alkaline phosphatase （ALP）. The result showed that there was an apparent relativity between plant biomass and the colonization rate and the enzyme activity of AM fungi. The colonization rate increased with the rising of pH value when the plants were inoculated with Glomus mosseae alone or with mixed strains, but when the plants were inoculated with Gigaspora margarita alone, the colonization rate was the highest at the level of pH 5.8 and then decreased at 6.8. In mixed inoculum experiment, the interaction of the two fungal species at different pH level was detected by nested PCR with special primers gml and gigl. At lower pH level（4.3-5.1）, most of roots were infected by Gigaspora margarita and Glomus mosseae apparently decreased the colonization of Gigaspora margarita. At higher pH level（5.8-6.8）, most of roots were infected by Glomus mosseae, and Gigaspora margarita effectively increased the colonization rate of Glomus mosseae. None of the roots were simultaneously infected by the two fungal species.