摘要:丛枝菌根真菌（AMF）可促进作物营养吸收和提高抗逆性，成为寄主抵御干旱胁迫的有效途径。为探明AMF提高大豆抗旱性的机制，以‘桂春豆103’为材料接种幼套近明囊霉（Claroideoglomus etunicatum，简写为C.e），研究干旱条件下C.e对田间大豆叶抗氧化酶及根围土中C/N/P循环相关酶活性等的影响，并用变性梯度凝胶电泳等方法探索土壤微生物群落结构的变化。结果表明：干旱处理前，接种C.e（+AM）处理大豆SOD、POD活性及游离脯氨酸（FP）含量，磷酸酶、蔗糖酶和脲酶活性，土壤细菌、真菌和放线菌数量及物种多样性、丰富度和群落均匀度指数，大豆生物量和株高均显著高于（-AM）处理（P < 0.05），MDA含量显著降低（P < 0.05）。干旱（D）处理后，+AM+D处理的上述各项指标，除MDA含量比-AM+D或+AM处理分别显著降低或升高（P < 0.05），FP含量比两处理显著提高（P < 0.05）外，其余指标值及细菌和真菌rDNA条带数均比-AM+D处理显著升高，比+AM处理显著下降（P < 0.05）。-AM+D与-AM处理的细菌和真菌群落均分别聚类于两不同分支，+AM与+AM+D处理聚于同一分支。可见，+AM+D处理能显著促进大豆抗氧化酶系统活性，维持较强的活性氧清除和渗透调节能力，缓解干旱对土壤酶活性的抑制，保持较高的细胞膜稳定性、土壤微生物数量和群落多样性，有利于C/N/P循环转化，提高抗旱性，最终促进大豆生长。本研究可为促进农业生态系统可持续发展奠定基础。
关键词:大豆/
丛枝菌根真菌/
干旱胁迫/
抗氧化代谢/
根围土壤微生物
Abstract:Arbuscular mycorrhizal fungi (AMF) not only improves nutrient absorption, but also enhances the resistance of host plant to stress such as drought. AMF inoculation has become one of the effective ways to resist drought stress. To explore the drought resistance mechanism of soybeans (Glycie max) inoculated with AMF, an experiment involving soybean variety 'Guichundou 103' as material was conducted. After inoculation with Claroideoglomus etunicatum (C.e), the effects of C.e on activities of antioxidant enzymes and C/N/P-cycle-related enzymes were investigated by collecting rhizospheric soil of soybean under drought stress. The changes in bacterial and fungal community diversities in rhizospheric soil were analyzed by denaturing gel gradient electrophoresis (DGGE) and other technologies. The results showed that activities of SOD, POD, sucrase, urease and phosphatase, free proline (FP) content, number and indexes of Shannon-Wiener diversity, richness and evenness of microorganisms in rhizospheric soil, as well as biomass and plant height of soybean with C.e inoculation (+AM) treatment were significantly higher than those without C.e inoculation (-AM) treatment under normal water supply condition. On the contrary, MDA content decreased significantly. Under drought stress (+D), MDA content with +AM treatment was lower and higher than that with -AM+D and +AM treatment, respectively. FP content was both higher than those of two treatments. The other indexes mentioned above along with band numbers of rDNA fragments of rhizospheric soil bacteria and fungi population were significantly higher than those with -AM+D treatment, and lower than those with +AM treatment. The bacterial and fungal communities of rhizospheric soil of -AM and -AM+D treatments belonged to different groups, while those of +AM treatment were clustered together with those of +AM+D treatment. In conclusion, +AM+D treatment obviously promoted the activities of antioxidant enzyme system, alleviated inhibition of drought on soil enzyme activities, kept high stability of cell membrane system, retained high population number and microbial structure diversity, promoted circulation and transformation of C, N and P in rhizospheric soil, improved drought resistance and effectively stimulated soybean growth. These results will lay a critical foundation for promoting sustainable development of agroecological systems.
Key words:Soybean (Glycie max)/
Arbuscular mycorrhizal fungi (AMF, Claroideoglomus etunicatum)/
Drought stress/
Antioxidant metabolism/
Rhizospheric soil microorganism
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