Research Progress in the Mechanism of CEP Regulating Plant Nutrient Uptake

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

Abstract

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

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.

Figures/Tables 2

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

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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