J Integr Plant Biol. ›› 2019, Vol. 61 ›› Issue (10): 1043-1061.DOI: 10.1111/jipb.12846

• Cell and Developmental Biology • Previous Articles     Next Articles

CLE25 peptide regulates phloem initiation in Arabidopsis through a CLERK-CLV2 receptor complex

Shi-Chao Ren1†, Xiu-Fen Song1†, Wen-Qiang Chen1,2, Ran Lu1, William J. Lucas3 and Chun-Ming Liu1,4*   

  1. 1Key Laboratory of Plant Molecular Physiology, Institute of Botany, Chinese Academy of Sciences, Nanxincun 20, Fragrant Hill, Beijing 100093, China
    2University of Chinese Academy of Sciences, Beijing 100049, China
    3Department of Plant Biology, College of Biological Sciences, University of California, Davis, CA 95616, USA
    4Institute of Crop Sciences, Chinese Academy of Agricultural Sciences, Beijing 100081, China

    These authors contributed equally to this work.
    Email: Chun-Ming Liu (cmliu@ibcas.ac.cn)
  • Received:2019-05-23 Accepted:2019-05-24 Online:2019-05-25 Published:2019-10-01

Abstract: The phloem, located within the vascular system, is critical for delivery of nutrients and signaling molecules throughout the plant body. Although the morphological process and several factors regulating phloem differentiation have been reported, the molecular mechanism underlying its initiation remains largely unknown. Here, we report that the small peptide‐coding gene, CLAVATA 3 (CLV3)/EMBEYO SURROUNDING REGION 25 (CLE25), the expression of which begins in provascular initial cells of 64‐cell‐staged embryos, and continues in sieve element‐procambium stem cells and phloem lineage cells, during post‐embryonic root development, facilitates phloem initiation in Arabidopsis. Knockout of CLE25 led to delayed protophloem formation, and in situ expression of an antagonistic CLE25G6T peptide compromised the fate‐determining periclinal division of the sieve element precursor cell and the continuity of the phloem in roots. In stems of CLE25G6T plants the phloem formation was also compromised, and procambial cells were over‐accumulated. Genetic and biochemical analyses indicated that a complex, consisting of the CLE‐RESISTANT RECEPTOR KINASE (CLERK) leucine‐rich repeat (LRR) receptor kinase and the CLV2 LRR receptor‐like protein, is involved in perceiving the CLE25 peptide. Similar to CLE25, CLERK was also expressed during early embryogenesis. Taken together, our findings suggest that CLE25 regulates phloem initiation in Arabidopsis through a CLERK‐CLV2 receptor complex.

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