The Center of Excellence in Molecular Plants has made progress in the study of the mechanism by which nitrate inhibits nodule formation

2022-04-26 0 By

Recently,The state Key Laboratory of Plant Molecular Genetics, Center for Excellence in Molecular Plant Science, Chinese Academy of Sciences (CAS), And Prof. Florian Frugier, University of Paris Thackeray/Institute of Plant Science, Paris Thackeray, France, jointly developed the NLP1 directly Controls expression of plant GenesThe peptid-encoding CEP1 gene in Response to L-glutamic acid 通 讯 作 者This study revealed the molecular mechanism of MtNLP1 transcription factor in Medicago Truncatula by binding to the half NRE (hNRE) element in the promoter of the small peptid-coding gene MtCEP1, which mediates nitrate inhibition of its expression.Nitrogen (N) is one of the essential nutrients in plants.Nitrate nitrogen can not only be directly absorbed and utilized by plants, but also can be used as an important signal molecule to regulate the expression of genes related to nitrogen response, absorption and metabolism, thus affecting the growth and development of plants.Legumes can obtain nitrogen for growth through symbiotic interactions with rhizobia, but symbiotic nitrogen fixation is an energy-consuming process.When high concentration of nitrogen exists in soil, nitrogen as a signal molecule will affect the function of symbiotic nitrogen fixation genes and thus inhibit the symbiotic nitrogen fixation process.Previous studies have shown that transcription factor MtNLP1 is a core component of nitrate nitrogen inhibition of nodule formation and inhibits nodule formation by regulating local and systemic pathways.The CEPs (C-terminally Encoded Peptides) encode a small peptide that is synthesized in the root of the plant and transported to the shoots, so as to systematically regulate the absorption of nitrogen through binding with its receptor.The expression level of the CEPs gene depends on the nitrogen concentration in the soil, and is induced under low nitrogen condition, while suppressed under high nitrogen condition.However, its expression regulation mechanism is still unclear.AtNLP7 has been reported in Arabidopsis thaliana to have inhibitory as well as activating functions.Therefore, the researchers hypothesized that MtNLP1 may be involved in nitrate inhibition of CEPs gene expression.In this study, the synthesis of MtCEP1 small peptide was added into wild-type and NLP1 mutants respectively to analyze whether MtCEP1 small peptide’s tumor-promoting effect was affected.The results showed that MtCEP1 was independent of MtNLP1 in promoting tumor formation, suggesting that MtCEP1 may act downstream of MtNLP1.Further transcriptional analysis confirmed that nitrate inhibition of CEP1 gene expression depended on MtNLP1.Using dexamethasone (DEX) induced expression system, we found that MtNLP1 inhibited MtCEP1 expression.The results of the dual-luciferase reporter system also showed that MtNLP1 could inhibit the activity of MtCEP1 promoter in response to nitrate.NRE (NRE) of CEP gene promoter was shorter than NRE of MtNLP1 activated gene, so the Element was named hNRE (half NRE).Further studies showed that hNRE on the CEP1 gene promoter is required for NLP1 binding, and hNRE is conserved on the CEP gene promoter in Arabidopsis thaliana, suggesting that this regulation is not only present in legumes.This study revealed that MtNLP1 can not only act as a transcription activator to activate the expression of MtCLE35 gene and mediate nitrate inhibition of nodulation, but also act as an inhibitor to inhibit the expression of CEP1 gene by binding to its promoter, thus having bifocal transcriptional activity.At the same time, this study also revealed the mechanism of nitrogen inhibition of CEP gene expression.Declaration: The copyright of this article belongs to the original author, if there is a source error or infringement of your legitimate rights and interests, you can contact us through the mailbox, we will promptly deal with.Email address: jpbl@jp.jiupainews.com