CEP调控植物养分吸收机理研究进展

doi:10.13560/j.cnki.biotech.bull.1985.2025-0383

摘要/Abstract

摘要：

活性多肽在调控植物生长发育、生物和非生物胁迫、根系养分吸收和豆科植物根系结瘤固氮等方面均发挥着重要的作用。C-末端编码肽（C-terminal encoded peptide, CEP）是由前体肽通过翻译后剪切修饰而成的含有15个氨基酸的多肽。CEP在响应低氮胁迫、非生物胁迫和豆科植物根瘤形成等方面均发挥着重要调控作用。低氮和盐胁迫可诱导根系CEP基因表达。根系合成的CEP多肽可通过木质部转运到地上部，与地上部CEP受体1（CEPR1）和CEP受体2（CEPR2）结合，通过CEP-CEPR信号通路调控植物根系生长、养分吸收和豆科植物根系结瘤。根系形态、根系养分吸收能力以及根际养分含量是影响植物养分吸收的关键，说明CEP在调控植物养分吸收中起着非常重要的作用。本文重点综述CEP在调控根系生长发育、根系养分吸收和根瘤形成中的作用机理，为下一步充分利用CEP功能，提高作物养分利用效率，促进农业绿色可持续发展提供理论依据。

关键词: CEP, CEPR, 氮吸收, 根系生长, 根系结瘤

Abstract:

Active peptides play important roles in regulating plant growth and development, biotic and abiotic stress, nutrient uptake in root, and legume nodulation and nitrogen fixation. C-terminal encoded peptide (CEP) is derived from precursor peptides through post-translational modification and mature CEP has 15 amino acids. CEP plays crucial regulatory roles in response to low nitrogen stress, abiotic stress, and legume nodulation formation. Low nitrogen and salt stress can induce the expression of CEP gene in the root. Root-synthesized CEP peptides secrete to the apoplast and then transport to the shoot. The CEP peptides bind the CEP receptor 1 (CEPR1) and CEP receptor 2 (CEPR2) in the shoot, thereby regulating root growth, nutrient uptake and legume nodulation formation through the CEP-CEPR signal pathway. The root morphology and nutrient absorption capacity, along with the nutrient content in the rhizosphere are key factors affecting plant nutrient absorption, which suggest that the CEP plays very important role in regulating nutrient uptake in plant. This review focuses on the mechanism of CEP in regulating root growth and development, nutrient absorption, and nodule formation, which may provide theoretical basis for fully utilizing the CEP in improving crop nutrient utilization efficiency and promoting green and sustainable development of agriculture.

Key words: CEP, CEPR, nitrogen absorption, root growth, root nodulation formation

段稀源, 罗振, 唐薇, 卢合全, 孔祥强. CEP调控植物养分吸收机理研究进展[J]. 生物技术通报, 2025, 41(10): 121-128.

DUAN Xi-yuan, LUO Zhen, TANG Wei, LU He-quan, KONG Xiang-qiang. Research Progress in the Mechanism of CEP Regulating Plant Nutrient Uptake[J]. Biotechnology Bulletin, 2025, 41(10): 121-128.

图/表 2

图1 CEP信号调控根系硝态氮吸收和生长的机理A：根系养分或盐分差异分布条件下，低氮或盐胁迫一侧根系CEP基因表达上调，合成CEP肽通过木质部转运至地上部，与CEP受体CEPR相互作用，致使CEPD基因表达上调，生成CEPD多肽并通过韧皮部转运回根系发挥作用。首先，高氮低盐条件与CEPD多肽能够特异性上调编码NRT2.1的转录本，从而促进NRT2.1蛋白合成；其次，CEPD多肽能够促进NRT1.1和NRT1.5的表达，同时低氮环境与CEPD诱导CEPH表达，激活NRT2.1的转运活性，从而促进硝态氮的吸收与转运。此外，CEPD还能通过抑制初生根生长来影响根系生长。B：根系合成的CEP转运至地上部，与CEP受体CEPR相互作用，一方面抑制侧根生长；另一方面CEPR诱导CEPD表达来抑制次生根向地性生长；细胞分裂素通过AHK2和AHK3也可促进CEPD基因在根系表达，提高根系CEPD含量，抑制次生根向地性生长

Fig. 1 Mechanism of CEP signaling in regulating nitrate uptake and root growthA: Under heterogeneous nutrient or salt distribution in the root system, low nitrogen (N) or salt stress on one side induces the upregulation of CEP gene expression in the stressed roots. The synthesized CEP peptides are transported to the shoot via the xylem, where they interact with the CEP receptor (CEPR). This interaction triggers the upregulation of CEPD gene expression, leading to the production of CEPD peptides, which are then transported back to the roots via the phloem to exert their effects. First, under high-N/low-salt conditions, CEPD peptides specifically upregulate the transcript encoding NRT2.1, promoting NRT2.1 protein synthesis. Second, CEPD peptides enhance the expressions of NRT1.1 and NRT1.5, thereby improving nitrate uptake and transport. Additionally, CEPH is induced under low-N conditions and further activates NRT2.1 transport activity in response to CEPD. Moreover, CEPD suppresses primary root growth, thus modulating root system architecture. B: The synthesized CEP peptides in the roots, are transported to the shoot. There, they interact with the CEP receptor (CEPR), generating a signal that suppresses lateral root growth. Furthermore, CEPR activates CEPD expression, which inhibits the gravitropic growth of secondary roots. Concurrently, cytokinins promote CEPD expression in the roots via AHK2 and AHK3, increasing CEPD levels in the roots and further suppressing secondary root gravitropism

图2 CEP调控植物与根瘤菌共生结瘤在调控根系结瘤过程中，CLEs和CEP家族肽表现出拮抗作用。低氮条件诱导植物根系CEP1表达，其产物通过木质部转运至地上部与CAR2结合，促进miR2111的合成并向根部运输，进而降低TML1和TML2蛋白积累以促进结瘤。同时，CRA2通过抑制乙烯信号依赖的相关基因表达来减弱乙烯对结瘤的抑制作用。在结瘤自调控途径中，根系产生的CLE12和CLE13通过激活地上部SUNN来抑制miR2111表达，从而抵消CEP信号对miR2111的上调作用。当外界氮含量较高时，NLP1一方面激活结瘤负调节因子CLE35表达，另一方面又抑制正调控因子CEP1的表达来实现对根系结瘤的调控

Fig. 2 CEP regulates symbiotic nodulation between plants and rhizobiaIn the regulation of root nodulation, CLEs and CEP family peptides demonstrate antagonistic effects. Under low nitrogen conditions, CEP1 expression is induced in plant roots, and its product is transported to the shoots via the xylem, where it binds to CAR2 to promote miR2111 synthesis and subsequent transport back to the roots, thereby reducing TML1 and TML2 protein accumulation to facilitate nodulation. Meanwhile, CRA2 suppresses ethylene-dependent signaling genes to attenuate the inhibitory effect of ethylene on nodulation. In the autoregulation pathway of nodulation, root-derived CLE12 and CLE13 activate SUNN in the shoots to inhibit miR2111 expression, thereby counteracting the CEP-mediated upregulation of miR2111. When external nitrogen levels are high, NLP1 activates the expression of the negative regulator CLE35 while simultaneously suppress the positive regulator CEP1 to modulate root nodulation

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