Rice transcription factor GAMYB modulates bHLH142 and is homeostatically regulated by TDR during anther tapetal and pollen development

Abstract

GAMYB, UDT1, TIP2/bHLH142, TDR, and EAT1/DTD are important transcription factors (TFs) that play a crucial role during rice pollen development. This study demonstrates that bHLH142 acts downstream of UDT1 and GAMYB and works as a “hub” in these two pollen pathways. We show that GAMYB modulates bHLH142 expression through specific binding to the MYB motif of bHLH142 promoter during early stage of pollen development; while TDR acts as a transcriptional repressor of the GAMYB modulation of bHLH142 by binding to the E-box close to the MYB motif on the promoter. The altered expression of TFs highlights the importance that a tight, precise, and coordinated regulation among these TFs is essential for normal pollen development. Most notably, this study illustrates the regulatory pathways of GAMYB and UDT1 that rely on bHLH142 in a direct and an indirect manner, respectively, and function in different tissues with distinct biological functions during pollen development. This study advances our understanding of the molecular mechanisms of rice pollen development.

Heterologous Expression of Dehydration-Inducible MfbHLH145 of Myrothamnus flabellifoli Enhanced Drought and Salt Tolerance in Arabidopsis

“…bHLH145 belongs to subfamily 13 of bHLH family in Arabisopsis [ 5 ], on which less attention has been paid. Rice bHLH142 plays a crucial role in pollen development [ 30 ], bHLH144 has been reported to be involved in activation of Wx to regulate grain quality in rice [ 31 ]. The functions of bHLH143 and bHLHL145 were previously unknown.…”

The GA–DELLA–OsMS188 module controls male reproductive development in rice

“…These two genes may contribute to the generation of H 2 O 2 and the hydrolysis of PCD‐inducing proteins, respectively (Phan et al ., 2011a). Previous research confirmed that OsAGO2 controls OsHXK1 expression via methylation to determine the timing of the tapetum degeneration‐associated abnormal accumulation of reactive oxygen species in anthers (Ko et al ., 2021). In the current study, the expression of these two genes was significantly affected in the slr1‐5 anthers (Fig.…”

“…In rice, several mutants, including gid1‐4 (GA receptor), gid2‐5 (F‐box protein involved in the degradation of a rice DELLA protein), oscps1‐1 ( ent ‐copalyl diphosphate synthase that catalyzes the first step of the GA biosynthesis pathway) and gamyb (GA response gene), reportedly exhibit a similarly defective PCD of tapetal cells and exine formation (Aya et al ., 2009). The GAMYB TF, which is homeostatically regulated by TDR, specifically modulates TIP2 and CYP703A3 expression to regulate tapetal development and exine formation (Aya et al ., 2009; Ko et al ., 2021). In Arabidopsis, the GAMYB‐like genes MYB33 and MYB65 , which are downstream targets of DELLA proteins, regulate tapetal PCD and male meiotic cytokinesis (Millar & Gubler, 2005).…”

Transcription factor FfMYB15 regulates the expression of cellulase gene FfCEL6B during mycelial growth of Flammulina filiformis

“…For example, in persimmon fruit, DkMYB4 participated in proanthocyanidin biosynthesis by binding to MYB motif in the promoter region of proanthocyanidin pathway genes [ 50 ]. In the early stage of rice pollen development, GAMYB regulated the expression of bHLH142 by binding to the MYB motif in the promoter region of bHLH142 [ 51 ]. In D. discoideum , the MYB motif in the promoter of cellulase CelB might bind to MYB protein to regulate the CelB gene expression [ 30 ].…”