The TIFY family protein CmJAZ1‐like negatively regulates petal size via interaction with the bHLH transcription factor CmBPE2 in Chrysanthemum morifolium

Abstract

SUMMARY Petals are the second floral whorl of angiosperms, exhibiting astonishing diversity in their size between and within species. This variation is essential for protecting their inner reproductive organs and attracting pollinators for fertilization. However, currently, the genetic and developmental control of petal size remains unexplored. Chrysanthemum (Chrysanthemum morifolium) belongs to the Asteraceae family, the largest group of angiosperms, and the extraordinary diversity of petal size in chrysanthemums makes it an ideal model for exploring the regulation mechanism of petal size. Here, we reveal that overexpression of a JAZ repressor CmJAZ1‐like exhibits decreased petal size compared to that of the wild‐type as a result of repressed cell expansion. Through further in‐depth exploration, we confirm an interaction pair between CmJAZ1‐like and the bHLH transcription factor CmBPE2. The inhibition of CmBPE2 expression negatively regulates petal size by downregulating the expression of genes involved in cell expansion. Furthermore, CmJAZ1‐like significantly reduced the activation ability of CmBPE2 on its target gene CmEXPA7 by directly interacting with it, thus participating in the regulation of petal size development in chrysanthemum. Our results will provide insights into the molecular mechanisms of petal size regulation in flowering plants.

Floral Development Stage-Specific Transcriptomic Analysis Reveals the Formation Mechanism of Different Shapes of Ray Florets in Chrysanthemum

“…GhWIP2 in Gerbera acts as a transcriptional repressor, suppressing cell expansion and reducing the length of ray florets by modulating crosstalk between GA, ABA, and auxin [ 60 ]. In addition, CmJAZ1, a repressor of the JA signaling pathway, and CmBES1, the BR-related transcription factor, were involved in regulating the morphology of ray florets [ 25 , 26 ]. It is evident that numerous plant hormone signals and related genes are involved in the regulation of ray floret morphogenesis.…”

“…In chrysanthemums, overexpressing CmBES1 resulted in an increased fusion of the peripheral ray florets [ 25 ]. Additionally, JASMONATE ZIM DOMAIN (CmJAZ1), a JAZ repressor, could repress petal cell expansion and decrease the size of ray florets [ 26 ]. The above studies showed that plant hormones significantly regulate the morphology of ray florets.…”

A GASA Protein Family Gene, CmGEG, Inhibits Petal Growth in Chrysanthemum

“…The petal length, cell lengths, and width were measured following the previously established protocols [ 25 ]. Approximately 1 mm 2 sections from the top, middle, and basal regions of the petals were excised and stained with 0.1 mg/mL propidium iodide (PI) at room temperature for 30 min, as outlined in previous studies [ 62 ]. The morphology of the upper epidermal cells was examined and documented using a laser confocal microscope (LSM800, Carl Zeiss, Oberkochen, Germany).…”

“…Notably, CnTCP9 promotes petal cell development and enhances flower size through the GA pathway [ 60 ]. Additionally, CmTCP20 , CmJAZ1-like , and CmBPE2 regulate flower size by influencing cell expansion [ 61 , 62 ].…”

Understanding the Molecular Regulatory Networks of Seed Size in Soybean

“…These proteins are characterized by the presence of a conserved domain known as the TIFY domain, which is essential for their function [76]. TIFY proteins are involved in the regulation of plant growth, development, and responses to multiple environmental stimuli, including both biotic and abiotic stresses [77,78]. They participate in signalling pathways that mediate plant defence against pathogens, modulate hormone signalling, and regulate plant responses to diverse stress conditions.…”