C-terminally encoded peptides (CEPs) are small peptides, typically post-translationally modified, and highly conserved in many species. CEPs are known to inhibit plant growth and development, but the mechanisms are not well understood. In this study, 14 CEPs were identified in Setaria italica and divided into two groups. The transcripts of most SiCEPs were more abundant in roots than in other detected tissues. SiCEP3, SiCEP4, and SiCEP5 were also highly expressed in panicles. Moreover, expression of all SiCEPs was induced by abiotic stresses and phytohormones. SiCEP3 overexpression and application of synthetic SiCEP3 both inhibited seedling growth. In the presence of abscisic acid (ABA), growth inhibition and ABA content in seedlings increased with the concentration of SiCEP3. Transcripts encoding eight ABA transporters and six ABA receptors were induced or repressed by synthetic SiCEP3, ABA, and their combination. Further analysis using loss-of-function mutants of Arabidopsis genes functioning as ABA transporters, receptors, and in the biosynthesis and degradation of ABA revealed that SiCEP3 promoted ABA import at least via NRT1.2 (NITRATE TRANSPORTER 1.2) and ABCG40 (ATP-BINDING CASSETTE G40). In addition, SiCEP3, ABA, or their combination inhibited the kinase activities of CEP receptors AtCEPR1/2. Taken together, our results indicated that the CEP-CEPR module mediates ABA signaling by regulating ABA transporters and ABA receptors in planta.
Bibliographical noteKAUST Repository Item: Exported on 2022-05-26
Acknowledgements: This work was supported by the National Key R&D Program of China (2018YFD1000704, 2018YFD1000700), the Major Program of Shandong Province Natural Science Foundation (ZR2018ZB0212), and the Natural Science Foundation of China (Grant number 31970292). We thank Dr. Heribert Hirt (Center for Desert Agriculture, King Abdullah University of Science and Technology) for kindly providing pyr1pyl24 mutant, and Prof. Yinggao Liu (Shandong Agricultural University, China) for the abi3, abi5, aba1, aba2, nced3, cyp707a1, and cyp707a2 mutants.
This publication acknowledges KAUST support, but has no KAUST affiliated authors.
ASJC Scopus subject areas
- Plant Science