Jasmonate-Inducible R2R3-MYB Transcription Factor Regulates Capsaicinoid Biosynthesis and Stamen Development in Capsicum

Abstract

Jasmonates (JAs) play an important role in plant developmental processes and regulate the biosynthesis of various specialized metabolites, and transcription factors are crucial in mediating JA signaling to regulate these processes. Capsaicinoids (Caps) are intriguing specialized metabolites produced uniquely by Capsicum species that give their fruits a pungent flavor to defend against herbivory and pathogens. In this study, we identify a R2R3-MYB transcription factor CaMYB108 and demonstrate its roles in regulating the biosynthesis of Caps and stamen development. Transcriptional analysis indicated that CaMYB108 was preferentially expressed in the flower and fruit, while the subcellular localization of CaMYB108 was shown to be the nucleus. Virus-induced gene silencing of CaMYB108 led to the expression of capsaicinoid biosynthetic genes (CBGs), and the contents of Caps dramatically reduce. Moreover, the CaMYB108-silenced plants showed delayed anther dehiscence and reduced pollen viability. Transient overexpression of CaMYB108 caused the expression of CBGs to be upregulated, and the Caps content significantly increased. The results of dual-luciferase reporter assays showed that CaMYB108 targeted CBG promoters. In addition, the expression of CaMYB108 and CBGs was inducible by methyl jasmonate and was consistent with the increased content of Caps. Overall, our results indicate that CaMYB108 is involved in the regulation of Caps biosynthesis and stamen development.

TRANSPARENT TESTA GLABRA1 (TTG1) regulates leaf trichome density in tea Camellia sinensis

“…Trichomes can synthesize, store and sometimes secrete large amounts and various types of specialized metabolites, such as terpenes, phenylpropanoid derivatives and flavonoids (van Der Hoeven et al 2000, Gang et al 2001, Valkama et al 2003. Secondary metabolites have become popular not only because of their significance in the protection of plants against environmental stressors but also because they have great commercial value as food additives or pharmaceuticals (Schilmiller et al 2008, Glas et al 2012, Chen et al 2017, Huchelmann et al 2017, Yan et al 2017, Sun et al 2019a. For example, Cistus salvifolius trichomes synthesize and store polyphenols that affect both radiation absorbance and plant desiccation, which evolved for adaptation to high light stress and poor soil conditions along Mediterranean coasts (Tattini et al 2007).…”

Genome-wide identification of the Capsicum bHLH transcription factor family: discovery of candidate regulator involved in the regulation of species-specific bioactive metabolites

“…However, whether carotenoid and capsaicinoid biosynthesis is regulated by bHLH TFs is still unknown. Our previous studies con rmed that MYB31, MYB108 and MYB48 are involved in capsaicinoid biosynthesis [11,12,50,51]. Speci cally, natural variations of the master regulator MYB31 promoter can affect capsaicinoid contents among different Capsicum species [11,50].…”

“…studies have demonstrated that capsaicinoids are produced after the condensation of phenylalanine and in fatty acid chain biosynthetic pathways ( Figure S1B) [11][12][13].…”

Systematic analysis of the Capsicum ERF transcription factor family: identification of regulatory factors involved in the regulation of species-specific metabolites

“…The biosynthetic pathway of capsaicinoids consists of two distinct pathways, the phenylalanine and chain fatty acid biosynthesis pathways, which are involved in a series of genes encoding enzymes involved in synthesis, such as Phe ammonia-lyase (Pal), caffeic acid O-methyltransferase (Comt) and a putative acyltransferase (AT3) ( Fig. S1B) [11][12][13].…”