Chin J Plan Ecolo ›› 2018, Vol. 42 ›› Issue (7): 764-773.DOI: 10.17521/cjpe.2018.0089

• Research Articles • Previous Articles     Next Articles

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

XU Li-Jiao1,2, HAO Zhi-Peng1, XIE Wei1,2, LI Fang1,2, CHEN Bao-Dong1,2,*()   

  1. 1 State Key Laboratory of Urban and Regional Ecology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China
    2 University of Chinese Academy of Sciences, Beijing 100049, China
  • Online:2018-07-20 Published:2018-06-11
  • Contact: Bao-Dong CHEN
  • Supported by:
    Supported by the Strategic Priority Research Program of the Chinese Academy of Sciences(XDB15030102);the National Natural Science Foundation of China(41371264);the National Natural Science Foundation of China(41401281)

Abstract:

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 Ca2+ 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 Ca2+ 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 Ca2+ 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.

Key words: arbuscular mycorrhizal fungi, drought stress, H+, Ca2+, non-invasive micro-test technology