CmBES1 is a regulator of boundary formation in chrysanthemum ray florets

Peilei Cheng,Lian Ding,Weimin Fang,Yanan Liu,Qian Hu,Sumei Chen,Yiman Yang,Jiaojiao Gao,Fadi Chen,Hua Cheng,Jiaxin Zhang,Hong Chen,Jiafu Jiang,Zixin Zhang

doi:10.1038/s41438-020-00351-8

Abstract

Chrysanthemum (Chrysanthemum morifolium) is an ideal model species for studying petal morphogenesis because of the diversity in the flower form across varieties; however, the molecular mechanisms underlying petal development are poorly understood. Here, we show that the brassinosteroid transcription factor BRI1-EMS-SUPPRESSOR 1 (CmBES1) in chrysanthemum (C. morifolium cv. Jinba) is important for organ boundary formation because it represses organ boundary identity genes. Chrysanthemum plants overexpressing CmBES1 displayed increased fusion of the outermost ray florets due to the loss of differentiation of the two dorsal petals, which developed simultaneously with the ventral petals. RNA-seq analysis of the overexpression lines revealed potential genes and pathways involved in petal development, such as CUP-SHAPED COTYLEDON (CUC2), CYCLOIDEA 4 (CYC4), genes encoding MADS-box transcription factors and homeodomain-leucine zippers (HD-Zips) and auxin pathway-related genes. This study characterizes the role of CmBES1 in ray floret development by its modulation of flower development and boundary identity genes in chrysanthemum.

Highlights

Organogenesis is the process of tissue production by multipotent progenitor cells and is common to all multicellular organisms[1]
The genomic sequence of CmBES1 was cloned from leaves of C. morifolium cv
Based on the CmBES1 regulation of the CTMD of the ray florets, we focused our analysis on the Differentially expressed genes (DEGs) related to organ boundary growth and flower development (Supplementary Table S2), which revealed genes related to the auxin pathway, such as the homologs of AUXIN RESPONSE FACTOR (ARF) and INDOLEACETIC ACIDINDUCED PROTEIN (IAA)

Summary

Introduction

Organogenesis is the process of tissue production by multipotent progenitor cells and is common to all multicellular organisms[1]. Lateral organs such as leaves and flowers are formed by lateral organ primordia, where cells are recruited from the periphery of the meristem[2]. Cell division maintains the stem cell population, while the growth of the surrounding cellular organ primordia is restricted and enters a quiescent state to form an organ boundary that separates itself from the central meristem and adjacent organs[3,4]. Organ boundaries are regulated by complex networks comprising transcription factors and miRNAs and the spatial distribution of growth-promoting hormones such. Spatial regulation of the brassinosteroid (BR) pathway is necessary for normal development of organ boundaries[6].

Methods

Results

Conclusion