Paxillus involutus strains MAJ and NAU mediate K(+)/Na(+) homeostasis in ectomycorrhizal Populus x canescens under sodium chloride stress.
Salt-induced fluxes of H(+), Na(+), K(+), and Ca(2+) were investigated in ectomycorrhizal (EM) associations formed by Paxillus involutus (strains MAJ and NAU) with the salt-sensitive poplar hybrid Populus × canescens. A scanning ion-selective electrode technique was used to measure flux profiles in non-EM roots and axenically grown EM cultures of the two P. involutus isolates to identify whether the major alterations detected in EM roots were promoted by the fungal partner. EM plants exhibited a more pronounced ability to maintain K(+)/Na(+) homeostasis under salt stress. The influx of Na(+) was reduced after short-term (50 mm NaCl, 24 h) and long-term (50 mm NaCl, 7 d) exposure to salt stress in mycorrhizal roots, especially in NAU associations. Flux data for P. involutus and susceptibility to Na(+)-transport inhibitors indicated that fungal colonization contributed to active Na(+) extrusion and H(+) uptake in the salinized roots of P. × canescens. Moreover, EM plants retained the ability to reduce the salt-induced K(+) efflux, especially under long-term salinity. Our study suggests that P. involutus assists in maintaining K(+) homeostasis by delivering this nutrient to host plants and slowing the loss of K(+) under salt stress. EM P. × canescens plants exhibited an enhanced Ca(2+) uptake ability, whereas short-term and long-term treatments caused a marked Ca(2+) efflux from mycorrhizal roots, especially from NAU-colonized roots. We suggest that the release of additional Ca(2+) mediated K(+)/Na(+) homeostasis in EM plants under salt stress.
College of Biological Sciences and Technology, Beijing Forestry University, Beijing 100083, People's Republic of China.
Jing
J
Li
Siqin
S
Bao
Yuhong
Y
Zhang
Xujun
X
Ma
Manika
M
Mishra-Knyrim
Jian
J
Sun
Gang
G
Sa
Xin
X
Shen
Andrea
A
Polle
Shaoliang
S
Chen
D001487:Basidiomycota / Q000187:drug effects / Q000502:physiology*; D002118:Calcium / Q000378:metabolism / Q000494:pharmacology; D003433:Crosses, Genetic; D006706:Homeostasis / Q000187:drug effects*; D007477:Ions; D038821:Mycorrhizae / Q000187:drug effects / Q000502:physiology; D018515:Plant Leaves / Q000187:drug effects / Q000378:metabolism; D018517:Plant Roots / Q000187:drug effects / Q000378:metabolism; D032107:Populus / Q000187:drug effects / Q000382:microbiology / Q000502:physiology*; D011188:Potassium / Q000378:metabolism*; D011522:Protons; D012964:Sodium / Q000378:metabolism*; D012965:Sodium Chloride / Q000494:pharmacology*; D013312:Stress, Physiological / Q000187:drug effects*; D013997:Time Factors
D007477:Ions; D011522:Protons; D012965:Sodium Chloride; D012964:Sodium; D011188:Potassium; D002118:Calcium