丛枝菌根真菌根外菌丝跨膜H^+和Ca^2+流对干旱胁迫的响应  

Transmembrane H^+ and Ca^(2+) fluxes through extraradical hyphae of arbuscular mycorrhizal fungi in response to drought stress

作　　者：徐丽娇 郝志鹏[1] 谢伟[1,2] 李芳 陈保冬 XU Li-Jiao;HAO Zhi-Peng;XIE Wei;LI Fang;CHEN Bao-Dong(State Key Laboratory of Urban and Regional Ecology,Research Center for Eco-Environmental Sciences,Chinese Academy of Sciences,Beijing 100085,China;University of Chinese Academy of Sciences,Beijing 100049,China)

机构地区：[1]中国科学院生态环境研究中心,城市与区域生态国家重点实验室,北京100085 [2]中国科学院大学,北京100049

出　　处：《植物生态学报》2018年第7期764-773,共10页Chinese Journal of Plant Ecology

基　　金：中国科学院战略性先导科技专项(XDB15030102);国家自然基金项目(41371264和41401281)

摘　　要：丛枝菌根真菌(AMF)能够和大多数陆地植物形成共生体系,对于植物生长发育和适应各种逆境胁迫具有重要作用。很多研究表明干旱胁迫下AMF能够促进宿主植物对水分的吸收从而增强植物抗旱能力,但目前针对AMF根外菌丝响应水分胁迫的生理变化以及AMF与宿主植物逆境信号交流的研究并不多。该研究利用AMF Rhizophagus irregularis和胡萝卜(Daucus carota var. sativa)毛状根双重无菌培养体系获得纯净根外菌丝,向培养基添加聚乙二醇(PEG)模拟干旱胁迫,运用场发射扫描电子显微镜(FE-SEM-EDS)观察干旱胁迫对AMF根外菌丝形态的影响,同时采用非损伤微测技术(NMT)观测根外菌丝跨膜H+和Ca^(2+)离子流变化。结果发现,PEG处理1h后菌丝尖端和侧面发生H+外流和强烈的Ca^(2+)内流,荧光探针分析也显示菌丝胞内pH值显著上升、Ca^(2+)浓度增加; PEG处理24 h后菌丝形态发生明显变化,培养基pH值降低, P、Ca、Fe等元素在菌丝际积累。这些试验结果表明,干旱胁迫下AMF根外菌丝跨膜H+和Ca^(2+)流发生变化,促进了菌丝与环境之间的物质交换。菌丝酸化生长环境有利于养分吸收,并促进AMF与宿主植物之间的信号交流以增强植物的耐旱性。Aims Arbuscular mycorrhizal fungi（AMF） can form symbiotic associations with most terrestrial plants to improve plant growth and stress resistance. It has been well demonstrated that AMF can promote plant acquisition of water and enhance plant tolerance to drought. In this study, AMF extraradical hyphae were obtained from in vitro culture of AMF Rhirophagus irregularis with hairy carrot（Daucus carota var. sativa） root to investigate the morphological and physiological changes of hyphae in response to drought stress induced by polyethylene glycol（PEG）. Methods The influence of drought stress on the hyphal morphology was observed by using the field emission-scanning electron microscope-energy dispersive X-ray spectroscopy（FE-SEM-EDS）, while H＋ and Ca^2＋ ion fluxes through living hyphae were monitored by non-invasive micro-test technique（NMT）. Important findings The results showed that significant H＋ efflux and Ca^2＋ influx through the tip and side of the extraradical hyphae were detected in response to drought stress induced by PEG for 1 h. Fluorescence probing confirmed that the intracellular pH value and Ca^2＋ concentration of hyphae significantly increased under PEG treatment. The morphology of hyphae changed and the pH value of the growth medium decreased after treatment with PEG for 24 h. The P, Ca, and Fe elements accumulated at the hyphosphere to enhance the nutrient absorption by hyphae. The study confirmed that AMF regulated the transmembrane H^＋ and Ca^2＋ flux to promote the material exchange between hyphae and environment under drought stress. The acidification of the hyphosphere environment potentially promoted the absorption of nutrients and also the signal exchange between AMF and the host plant to enhance plant drought tolerance.

关 键 词：丛枝菌根真菌 干旱胁迫 氢离子 钙离子 非损伤微测技术 

分 类 号：Q935[生物学—微生物学] Q945