BIK1 and ERECTA Play Opposing Roles in Both Leaf and Inflorescence Development in Arabidopsis.

Sufen Chen,Lijuan Chen,Yu Liu,Nan Yao,Jun Liu,Ting Sun,Bing Liu,Hong-Bin Wang

doi:10.3389/fpls.2019.01480

Abstract

Plants employ cell-surface receptor-like kinases to detect extrinsic and intrinsic signals, thus make a trade-off between growth and immunity. The receptor-like cytoplasmic kinases on the cytoplasmic side act as downstream components involved in the activation, transmission, and integration of intracellular signals. In Arabidopsis thaliana, the RLCK BOTRYTIS-INDUCED KINASE1 (BIK1) associates with multiple RLKs to regulate pathogen defense responses and brassinosteroid (BR) signaling. However, little is known about the biological functions of BIK1 in developmental processes in Arabidopsis. In this study, we established that mutation of ERECTA (ER), an important RLK, counteracts the developmental effects of loss of BIK1 function. BIK1 and ER play opposing roles in leaf morphogenesis and inflorescence architecture. Moreover, we confirmed that BIK1 is required to maintain appropriate auxin response during leaf margin morphogenesis. Finally, we found that BIK1 interacts with ER-family proteins and directly phosphorylates ER. Our findings might provide novel insight into the function of BIK1 in leaf and inflorescence development.

Highlights

Plants use cell-surface-localized receptor-like kinases to perceive diverse signals, such as plantderived sterols and peptides, and pathogen-derived molecules (Shiu and Bleecker, 2001), which trigger complex cellular networks with distinct signaling outputs (Belkhadir et al, 2014)
In order to elucidate the molecular mechanism that underlies the developmental phenotypes of bik1, we carried out an EMS-based genetic screen of mutants which modified the phenotypes of bik1 and named as modifier of bik1 developmental phenotypes (Figure 1A)
By SNP-based whole-genome deep sequencing, we found that both mobd1 and mobd2 carried a mutation in ER gene, as a C1381-to-T mutation in mobd1 resulting in the conversion of 191th amino acid in the sixth LRR domain from Gln to a premature stop codon, and a G1696-to-A mutation in the ninth intron of ER gene in mobd2 (Figure 1C), similar result was obtained with polymerase chain reaction (PCR) amplification and sequencing

Summary

Introduction

Plants use cell-surface-localized receptor-like kinases to perceive diverse signals, such as plantderived sterols and peptides, and pathogen-derived molecules (Shiu and Bleecker, 2001), which trigger complex cellular networks with distinct signaling outputs (Belkhadir et al, 2014). The RLKs CLAVATA1 and ERECTA recognize the CLAVATA3 peptide and epidermal patterning factors (EPFs)/EPF-like proteins (EPFLs), respectively (Ogawa et al, 2008), all of which play essential roles in plant growth and development. Members of the ER family recognize EPF1, EPF2, and EPFL9 to control stomatal patterning (Shpak et al, 2005; Hunt et al, 2010; Lee et al, 2012), whereas EPFL4 and EPFL6 have been identified as ligands of ER in the regulation of inflorescence architecture (Abrash et al, 2011; Uchida et al, 2012), and EPFL2 is recognized by ER-family proteins to control the development of leaf serrations (Tameshige et al, 2016). The molecular mechanism that underlies how ER transmits signals to control the development of leaf and inflorescence remains unclear

Methods

Results

Conclusion