Amelioration of nitrate uptake under salt stress by ectomycorrhiza with and without a Hartig net. Issue 4 (14th March 2019)

• Record Type: Journal Article
• Authors: Sa, Gang; Yao, Jun; Deng, Chen; Liu, Jian; Zhang, Yinan; Zhu, Zhimei; Zhang, Yuhong; Ma, Xujun; Zhao, Rui; Lin, Shanzhi; Lu, Cunfu; Polle, Andrea; Chen, Shaoliang
• Is Part Of: New phytologist. Volume 222:Issue 4(2019)
• Page Start: 1951
• Page End: 1964
• Publication Date: 2019-03-14
• Subjects: MAJ -- NaCl -- NAU -- NO3− flux -- NRTs -- Paxillus involutus -- pH -- Poplar; Botany -- Periodicals; 580
• DOI: 10.1111/nph.15740
• Languages: English
• ISSNs: 0028-646X

Abstract

Summary: Salt stress is an important environmental cue impeding poplar nitrogen nutrition. Here, we characterized the impact of salinity on proton‐driven nitrate fluxes in ectomycorrhizal roots and the importance of a Hartig net for nitrate uptake. We employed two Paxillus involutus strains for root colonization: MAJ, which forms typical ectomycorrhizal structures (mantle and Hartig net), and NAU, colonizing roots with a thin, loose hyphal sheath. Fungus‐colonized and noncolonized Populus × canescens were exposed to sodium chloride and used to measure root surface pH, nitrate (NO3 − ) flux and transcription of NO3 − transporters (NRTs; PcNRT1.1, ‐ 1.2, ‐ 2.1 ), and plasmalemma proton ATPases (HAs; PcHA4, ‐ 8, ‐11 ). Paxillus colonization enhanced root NO3 − uptake, decreased surface pH, and stimulated NRT s and HA4 of the host regardless the presence or absence of a Hartig net. Under salt stress, noncolonized roots exhibited strong net NO3 − efflux, whereas beneficial effects of fungal colonization on surface pH and HAs prevented NO3 − loss. Inhibition of HAs abolished NO3 − influx under all conditions. We found that stimulation of HAs was crucial for the beneficial influence of ectomycorrhiza on NO3 − uptake, whereas the presence of a Hartig net was not required for improved NO3 − translocation. Mycorrhizas may contribute to host adaptation to salt‐affected environments by keeping up NO3 − nutrition.