Identification of P-type plasma membrane H^(+)-ATPases in common wheat and characterization of TaHA7 associated with seed dormancy and germination

The P-type plasma membrane(PM)H^(+)-ATPases(HAs)are crucial for plant development,growth,and defense.The HAs have been thoroughly characterized in many different plants.However,despite their importance,the functions of HAs in germination and seed dormancy(SD)have not been validated in wheat.Here,we identified 28 TaHA genes(TaHA1-28)in common wheat,which were divided into five subfamilies.An examination of gene expression in strong-and weak-SD wheat varieties led to the discovery of six candidate genes(TaHA7/-12/-14/-16/-18/-20).Based on a single nucleotide polymorphism(SNP)mutation(C/T)in the TaHA7 coding region,a CAPS marker(HA7)was developed and validated in 168 wheat varieties and 171 Chinese mini-core collections that exhibit diverse germination and SD phenotypes.We further verified the roles of the two allelic variations of TaHA7 in germination and SD using wheat mutants mutagenized with ethyl methane sulphonate(EMS)in‘Jimai 22’and‘Jing 411’backgrounds,and in transgenic Arabidopsis lines.TaHA7 appears to regulate germination and SD by mediating gibberellic acid(GA)and abscisic acid(ABA)signaling,metabolism,and biosynthesis.The results presented here will enable future research regarding the TaHAs in wheat.

Changes of Plasma Membrane H^+-ATPase Activities of Glycine max Seeds by PEG Treatment

The soybean （Glycine max） Heihe No. 23 is sensitive to imbibitional chilling injury. Polyethylene glycol （PEG） treatment can improve chilling tolerance of soybean seeds to a certain extent. The changes of hydrolytic ATPase in plasma membranes and H^＋-pumping responses in soybean seeds were investigated during PEG treatments. Effects of exogenous calcium and exogenous ABA on the hydrolytic ATPase were also examined in order to understand the mechanism of chilling resistance. Highly purified plasma membranes were isolated by 6.0% aqueous two-phase partitioning from soybean seeds, as judged by the sensitivity of hydrolytic ATPase to sodium vanadate. PEG treatment resulted in a slight increase of the hydrolytic ATPase activity in 12 h. Then the activity decreased gradually, but still higher than the control. The H^＋-pumping activity increased steadily during PEG treatment. Exogenous calcium had both activating and inhibiting effects on the hydrolytic ATPase, but the activity was inhibited in soybean seeds treated with exogenous ABA. Results suggested that PEG treatment, not the exogenous calcium and ABA, up-regulated H^＋-ATPase activities in soybean seeds.

A critical review on natural compounds interacting with the plant plasma membrane H^(+)-ATPase and their potential as biologicals in agriculture

The plant plasma membrane(PM)H^(+)-ATPase is an essential enzyme controlling plant growth and development.It is an important factor in response to abiotic and biotic stresses and is subject to tight regulation.We are in demand for new sustainable natural growth regulators and as a key enzyme for regulation of transport into the plant cell the PM H^(+)-ATPase is a potential target for these.In this review,we have evaluated the known non-protein natural compounds with regulatory effects on the PM H^(+)-ATPase,focusing on their mechanism of action and their potential as biologicals/growth regulators in plant production of future sustainable agriculture.

Testing the polar auxin transport model with a selective plasma membrane H^(+)-ATPase inhibitor

Auxin is unique among plant hormones in that its function requires polarized transport across plant cells.A chemiosmotic model was proposed to explain how polar auxin transport is derived by the H^(+)gradient across the plasma membrane(PM)established by PM H^(+)-adenosine triphosphatases(ATPases).However,a classical genetic approach by mutations in PM H^(+)-ATPase members did not result in the ablation of polar auxin distribution,possibly due to functional redundancy in this gene family.To confirm the crucial role of PM H^(+)-ATPases in the polar auxin transport model,we employed a chemical genetic approach.Through a chemical screen,we identified protonstatin-1(PS-1),a selective small-molecule inhibitor of PM H^(+)-ATPase activity that inhibits auxin transport.Assays with transgenic plants and yeast strains showed that the activity of PM H^(+)-ATPases affects auxin uptake as well as acropetal and basipetal polar auxin transport.We propose that PS-1 can be used as a tool to interrogate the function of PM H^(+)-ATPases.Our results support the chemiosmotic model in which PM H^(+)-ATPase itself plays a fundamental role in polar auxin transport.

The fungal endophyte Epichloëgansuensis increases NaCltolerance in Achnatherum inebrians through enhancing the activity of plasma membrane H^(+)-ATPase and glucose-6-phosphate dehydrogenase

Salt stress negatively affects plant growth,and the fungal endophyte Epichloëgansuensis increases the tolerance of its host grass species,Achnatherum inebrians,to abiotic stresses.In this work,we first evaluated the effects of E.gansuensis on glucose-6-phosphate dehydrogenase(G6PDH)and plasma membrane(PM)H^(+)-ATPase activity of Achnatherum inebrians plants under varying NaCl concentrations.Our results showed that the presence of E.gansuensis increased G6PDH,PMH^(+)-ATPase,superoxide dismutase and catalase activity to decrease O2•^(–),H_(2)O_(2)and Na^(+)contents in A.inebrians under NaCl stress,resulting in enhanced salt tolerance.In addition,the PM NADPH oxidase activity and NADPH/NADP+ratios were all lower in A.inebrians with E.ganusensis plants than A.inebrians plants without this endophyte under NaCl stress.In conclusion,E.gansuensis has a positive role in improving host grass yield under NaCl stress by enhancing the activity of G6PDH and PM H^(+)-ATPase to decrease ROS content.This provides a new way for the selection of stress-resistant and high-quality forage varieties by the use of systemic fungal endophytes.