王存等《Journal of integrative plant biology》2020年
论文题目：Abscisic acid signaling negatively regulates nitrate uptake via phosphorylation of NRT1.1 by SnRK2s in Arabidopsis
论文作者：Hang Su , Tian Wang, Chuanfeng Ju, Jinping Deng , Tianqi Zhang , Mengjiao Li , Hui Tian , Cun Wang
该研究通过反向遗传学手段发现ABA信号的核心组分，尤其是第三亚族的SnRK2s，在低氮胁迫下的幼苗生长和硝态氮吸收过程中发挥了重要作用。在低氮胁迫条件下，snrk2.2snrk2.3snrk2.6 三突变体表现为主根较长，硝态氮吸收和积累明显增多。进一步研究表明，SnRK2.2/3/6与NRT1.1物理互作，并能通过磷酸化抑制其转运活性。此外， NRT1.1的第585位丝氨酸是功能磷酸化位点。NRT1.1Ser585D（模拟磷酸化状态）的低亲和性及高亲和性氮转运活性均显著降低，但对ABA表现出一定的耐受性。综上所述，该研究揭示了植物在低氮胁迫下通过ABA平衡逆境适应与生长发育的分子机制，为兼具抗逆特性和氮高效利用的作物改良奠定了理论基础。
论文摘要：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 2S (SnRK2) proteins, function in root foraging and uptake of nitrate under N deficiency in Arabidopsis thaliana. The snrk2.2snrk2.3snrk2.6 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 SnRK2s 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 NRT1.1S585D 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.