Nitrogen （N） is one of most important nutrients for crop production, which makes up 1%-5% of total plant dry matter （Marschner, 2012）. Due to the limited availability of N in soil, application of N fertilizers has...Nitrogen （N） is one of most important nutrients for crop production, which makes up 1%-5% of total plant dry matter （Marschner, 2012）. Due to the limited availability of N in soil, application of N fertilizers has been an important agronomic practice to increase crop yield. However, over-application of N fertilizers has caused pollution of N in soil, water and air. It was estimated that the nitrogen use efficiency （NUE, the total biomass or grain yield produced per unit of applied fertilizer N） in cereal crops is as low as 33% （Raun and Johnson, 1999）. Therefore, improving NUE together with reducing application of N fertilizers is an important issue for environment and sustainable production of crops. This is especially important for rice, which is a staple food for half population in the world.展开更多
Nitrogen(N)is a limiting nutrient for plant growth and productivity.The phytohormone abscisic acid(ABA)has been suggested to play a vital role in nitrate uptake in fluctuating N environments.However,the molecular mech...Nitrogen(N)is a limiting nutrient for plant growth and productivity.The phytohormone abscisic acid(ABA)has been suggested to play a vital role in nitrate uptake in fluctuating N environments.However,the molecular mechanisms underlying the involvement of ABA in N deficiency responses are largely unknown.In this study,we demonstrated that ABA signaling components,particularly the three subclass Ⅲ SUCROSE NON-FERMENTING1(SNF1)-RELATED PROTEIN KINASE 2 S(SnRK2)proteins,function in root foraging and uptake of nitrate under N deficiency in Arabidopsis thaliana.The snrk2.2 snrk2.3 snrk2.6 triple mutant grew a longer primary root and had a higher rate of nitrate influx and accumulation compared with wild-type plants under nitrate deficiency.Strikingly,SnRK2.2/2.3/2.6 proteins interacted with and phosphorylated the nitrate transceptor NITRATE TRANSPORTER1.1(NRT1.1)in vitro and in vivo.The phosphorylation of NRT1.1 by SnRK2 s resulted in a significant decrease of nitrate uptake and impairment of root growth.Moreover,we identified NRT1.1Ser585 as a previously unknown functional site:the phosphomimetic NRT1.1S585 D was impaired in both low-and high-affinity transport activities.Taken together,our findings provide new insight into how plants fine-tune growth via ABA signaling under N deficiency.展开更多
Ammonium(NH_(4)^(+))and nitrate(NO_(3)^(-))are major inorganic nitrogen(N)sources for plants.When serving as the sole or dominant N supply,NH_(4)^(+)often causes root inhibition and shoot chlorosis in plants,known as ...Ammonium(NH_(4)^(+))and nitrate(NO_(3)^(-))are major inorganic nitrogen(N)sources for plants.When serving as the sole or dominant N supply,NH_(4)^(+)often causes root inhibition and shoot chlorosis in plants,known as ammonium toxicity.NO_(3)^(-) usually causes no toxicity and can mitigate ammonium toxicity even at low concentrations,referred to as nitrate-dependent alleviation of ammonium toxicity.Our previous studies indicated a NO_(3)^(-) efflux channel SLAH3 is involved in this process.However,whether additional components contribute to NO_(3)^(-)-mediated NH_(4)^(+)detoxification is unknown.Previously,mutations in NO_(3)^(-) transporter NRT1.1 were shown to cause enhanced resistance to high concentrations of NH_(4)^(+).Whereas,in this study,we found when the high-NH_(4)^(+) medium was supplemented with low concentrations of NO_(3)^(-),nrt1.1 mutant plants showed hyper-sensitive phenotype instead.Furthermore,mutation in NRT1.1 caused enhanced medium acidification under high-NH_(4)^(+)/Iow-NO_(3)^(-) condition,suggesting NRT1.1 regulates ammonium toxicity by facilitating H+uptake.Moreover,NRT1.1 was shown to interact with SLAH3 to form a transporter-channel complex.Interestingly,SLAH3 appeared to affect NO_(3)^(-) influx while NRT1.1 influenced NO_(3)^(-) efflux,suggesting NRT1.1 and SLAH3 regulate each other at protein and/or gene expression levels.Our study thus revealed NRT1.1 and SLAH3 form a functional unit to regulate nitrate-dependent alleviation of ammonium toxicity through regulating NO_(3)^(-) transport and balancing rhizosphere acidification.展开更多
文摘Nitrogen （N） is one of most important nutrients for crop production, which makes up 1%-5% of total plant dry matter （Marschner, 2012）. Due to the limited availability of N in soil, application of N fertilizers has been an important agronomic practice to increase crop yield. However, over-application of N fertilizers has caused pollution of N in soil, water and air. It was estimated that the nitrogen use efficiency （NUE, the total biomass or grain yield produced per unit of applied fertilizer N） in cereal crops is as low as 33% （Raun and Johnson, 1999）. Therefore, improving NUE together with reducing application of N fertilizers is an important issue for environment and sustainable production of crops. This is especially important for rice, which is a staple food for half population in the world.
基金funded by a grant from the Northwest A&F University(Z111021604 to C.W.)the National Natural Science Foundation of China(31770289 to C.W.)+1 种基金Natural Science Basic Research Plan in Shaanxi Province of China(2019JQ-135 to C.W.)the Opening Research Projects of National Key Laboratory of Plant Molecular Genetics,CEMPS,CAS。
文摘Nitrogen(N)is a limiting nutrient for plant growth and productivity.The phytohormone abscisic acid(ABA)has been suggested to play a vital role in nitrate uptake in fluctuating N environments.However,the molecular mechanisms underlying the involvement of ABA in N deficiency responses are largely unknown.In this study,we demonstrated that ABA signaling components,particularly the three subclass Ⅲ SUCROSE NON-FERMENTING1(SNF1)-RELATED PROTEIN KINASE 2 S(SnRK2)proteins,function in root foraging and uptake of nitrate under N deficiency in Arabidopsis thaliana.The snrk2.2 snrk2.3 snrk2.6 triple mutant grew a longer primary root and had a higher rate of nitrate influx and accumulation compared with wild-type plants under nitrate deficiency.Strikingly,SnRK2.2/2.3/2.6 proteins interacted with and phosphorylated the nitrate transceptor NITRATE TRANSPORTER1.1(NRT1.1)in vitro and in vivo.The phosphorylation of NRT1.1 by SnRK2 s resulted in a significant decrease of nitrate uptake and impairment of root growth.Moreover,we identified NRT1.1Ser585 as a previously unknown functional site:the phosphomimetic NRT1.1S585 D was impaired in both low-and high-affinity transport activities.Taken together,our findings provide new insight into how plants fine-tune growth via ABA signaling under N deficiency.
基金supported by the National Natural Science Foundation of China(31870235,32170280)the 111 Project(B16022)the Fundamental Research Funds for the Central Universities(lzujbky-2019-kb05,lzujbky-2020-kb05,lzujbky-2021-it22)。
文摘Ammonium(NH_(4)^(+))and nitrate(NO_(3)^(-))are major inorganic nitrogen(N)sources for plants.When serving as the sole or dominant N supply,NH_(4)^(+)often causes root inhibition and shoot chlorosis in plants,known as ammonium toxicity.NO_(3)^(-) usually causes no toxicity and can mitigate ammonium toxicity even at low concentrations,referred to as nitrate-dependent alleviation of ammonium toxicity.Our previous studies indicated a NO_(3)^(-) efflux channel SLAH3 is involved in this process.However,whether additional components contribute to NO_(3)^(-)-mediated NH_(4)^(+)detoxification is unknown.Previously,mutations in NO_(3)^(-) transporter NRT1.1 were shown to cause enhanced resistance to high concentrations of NH_(4)^(+).Whereas,in this study,we found when the high-NH_(4)^(+) medium was supplemented with low concentrations of NO_(3)^(-),nrt1.1 mutant plants showed hyper-sensitive phenotype instead.Furthermore,mutation in NRT1.1 caused enhanced medium acidification under high-NH_(4)^(+)/Iow-NO_(3)^(-) condition,suggesting NRT1.1 regulates ammonium toxicity by facilitating H+uptake.Moreover,NRT1.1 was shown to interact with SLAH3 to form a transporter-channel complex.Interestingly,SLAH3 appeared to affect NO_(3)^(-) influx while NRT1.1 influenced NO_(3)^(-) efflux,suggesting NRT1.1 and SLAH3 regulate each other at protein and/or gene expression levels.Our study thus revealed NRT1.1 and SLAH3 form a functional unit to regulate nitrate-dependent alleviation of ammonium toxicity through regulating NO_(3)^(-) transport and balancing rhizosphere acidification.
