Coumarin enhances nitrate uptake in maize roots through modulation of plasma membrane H⁺‐ATPase activity

Abstract

Coumarin is one of the simplest plant secondary metabolites, widely distributed in the plant kingdom, affecting root form and function, including anatomy, morphology and nutrient uptake. Although, some plant responses to coumarin have been described, comprehensive knowledge of the physiological and molecular mechanisms is lacking. Maize seedlings exposed to different coumarin concentrations, alone or in combination with 200 μm nitrate (NO ), were analysed, through a physiological and molecular approach, to elucidate action of coumarin on net NO uptake rate (NNUR). In detail, the time course of NNUR, plasma membrane (PM) H -ATPase activity, proton pumping and related gene expression (ZmNPF6.3, ZmNRT2.1, ZmNAR2.1, ZmHA3 and ZmHA4) were evaluated. Coumarin alone did not affect nitrate uptake, PM H -ATPase activity or transcript levels of ZmNRT2.1 and ZmHA3. In contrast, coumarin alone increased ZmNPF6.3, ZmNAR2.1 and ZmHA4 expression in response to abiotic stress. When coumarin and NO were concurrently added to the nutrient solution, a significant increase in the NNUR, PM H -ATPase activity, together with ZmNAR2.1:ZmNRT2.1 and ZmHA4 expression was observed, suggesting that coumarin affected the inducible component of the high affinity transport system (iHATS), and this effect appeared to be mediated by nitrate. Moreover, results with vanadate, an inhibitor of the PM H -ATPase, suggested that this enzyme could be the main target of coumarin. Surprisingly, coumarin did not affect PM H -ATPase activity by direct contact with plasma membrane vesicles isolated from maize roots, indicating its possible elicitor role in gene transcription.

Natural variation of an EF-hand Ca2+-binding-protein coding gene confers saline-alkaline tolerance in maize

“…The optimal cytoplasmic pH for plant cells is neutral pH. When the rhizosphere pH is lower than the pH in the cytosolic of root cells, the H + gradient across the plasma membrane (membrane potential) drives uptake of nutrients (e.g., phosphorus, nitrate and iron) [19][20][21] . Under saline-alkaline condition, plants have to export cellular H + to rhizosphere to maintain the membrane potential 22,23 , and the PM-H + -ATPase is the major pump mediating root H + efflux 6 .…”

The effects of allelochemicals from root exudates of Flaveria bidentis on two Bacillus species

“…Allelopathy directly influences the growth of surrounding plants ( Schalchli et al., 2012 ; He et al., 2019 ). Phenolics and their derivatives, terpenoids, and alkaloids are the main categories of plant allelochemicals ( Qu and Wang, 2008 ; Li et al., 2010 ; Lupini et al., 2018 ; Wang et al., 2018 ), which are released through different means, such as in root exudate, volatiles from leaves, and through decomposition products ( Li et al., 2016 ). Allelochemicals can affect the soil microbial community, alter the soil nutrient cycle, and indirectly influence plant growth and interspecific competition among plant species ( Zhang et al., 2021 ).…”

Genome-Wide Analysis of the UDP-Glycosyltransferase Family Reveals Its Roles in Coumarin Biosynthesis and Abiotic Stress in Melilotus albus

“…Once synthesized, coumarins are glycosylated and stored in vacuoles [ 4 ], as the glycoside form is easier to store and transport. Coumarin affects plant growth and development and is part of the defense response to abiotic stress [ 5 ], shapes the root-associated microbial community [ 6 ], enhances oxidative stress [ 7 ] and nitrate uptake [ 8 ], and protects host plants from fungi [ 9 ]. To date, coumarins are thought to play certain roles in plant defense due to the induction of their biosynthesis following various stresses [ 10 ].…”