Alleviation of proton toxicity by nitrate uptake specifically depends on nitrate transporter 1.1 in Arabidopsis

Abstract

SummaryProtons in acid soil are highly rhizotoxic to plants, but the mechanism of tolerance of plants to protons is largely unknown. Nitrate uptake by root cells is accompanied by the uptake of protons. Therefore, nitrate uptake transporters (NRTs) may be involved in plant tolerance to proton toxicity.We investigated the root nitrate uptake response to proton stress in Arabidopsis and its association with proton tolerance using NRT-related mutants and pharmacological methods.Lack of NRT1.1 in knockout nrt1.1 mutants led to impaired proton tolerance in nitratesufficient growth medium, whereas no difference was seen between wild-type plants and NRT1.2-, NRT2.1-, NRT2.2-, and NRT2.4-null mutants. Another nrt1.1 point mutant, which is defective in nitrate uptake but has a normal nitrate-sensing function, also had impaired proton tolerance compared with the wild-type plant. Furthermore, proton stress induced NRT1.1-mediated nitrate uptake. These results indicate that NRT1.1-conferred proton tolerance depends on nitrate uptake activity. In addition, the rooting medium was alkalified by wild-type plants, but not by knockout nrt1.1 mutants, and in pH-buffered medium, there were no differences in proton tolerance between wild-type plants and knockout nrt1.1 mutants.We conclude that NRT1.1-mediated nitrate uptake plays a crucial role in plant proton tolerance by alkalifying the rhizosphere.

Trichoderma-Induced Acidification Is an Early Trigger for Changes in Arabidopsis Root Growth and Determines Fungal Phytostimulation

“…The fact that the Arabidopsis aux1-7 mutant is hypersensitive to low pH, suggests an important role of auxin transport in root growth response to acidification (Inoue et al, 2016), and since the same mutant had a reduced response to T. virens inoculation in terms of shoot biomass production and lateral root development (Contreras-Cornejo et al, 2009), we propose that normal auxin transport is important for plant growth and root adaptation to low pH following Trichoderma inoculation. In addition, the nitrate transporters NRT1.1 and OsNRT2.3b are involved in H + resistance in Arabidopsis and rice, respectively, a phenomenon that depends on their nitrate uptake activity (Fang et al, 2016; Fan et al, 2016b). The relationship of Trichoderma with nitrate nutrition of plants represents an interesting research avenue to follow.…”

Inhibition of DNA demethylation enhances plant tolerance to cadmium toxicity by improving iron nutrition

“…All quantitative PCR analyses were performed in a StepOnePlus RT‐PCR system (Thermo Fisher Scientific) using the SYBR Green RT‐PCR kit (Toyobo, Osaka, Osaka Prefecture, Japan), and the primers are listed in Table S1. The relative expression levels were calculated following a procedure described previously (Fang et al, ).…”

Ethylene and nitric oxide interact to regulate the magnesium deficiency‐induced root hair development in Arabidopsis

“…An Eppendorf Mastercycler ep realplex was used to perform the qPCR. The relative expression levels were calculated using an efficiency-corrected DDC t formula (Fang et al, 2016).…”