AmMYB24 Regulates Floral Terpenoid Biosynthesis Induced by Blue Light in Snapdragon Flowers

Abstract

Floral terpenoid volatiles are impacted by light quality. In snapdragon, blue light can significantly enhance the emissions of ocimene and myrcene and the expression of ocimene synthase (AmOCS) and myrcene synthase (AmMYS). However, the mechanisms underlying the response to blue light are largely unknown. In this study, two transcription factors (TFs), AmMYB24 and AmMYB63 were screened which showed high expression level under blue light. AmMYB24 exhibited synchronous expression with AmOCS. Moreover, AmOCS transcript expression was up-regulated in response to AmMYB24 overexpression. This activation is direct and occurs through binding of AmMYB24 to MYBCORECYCATB1 sites in the AmOCS promoter. In addition, AmMYB24 interacts with the blue light signal key receptor AmCRY1 and the transcriptional activation activity of AmMYB24 was decreased in AmCRY1 silencing flowers. Taken together, our results revealed the regulatory pathway of biosynthesis of ocimene induced by blue light mediated by AmMYB24 and AmCRY1. When snapdragon flowers were exposed to blue light, AmCRY1 was first activated, the light signal is transduced to AmMYB24 through interaction with AmCRY1, and finally AmMYB24 activates AmOCS by binding to its MYBCOREATCYCB1 motif, resulting in abundant ocimene emission.

AmPIF4 negatively regulates the blue light-induced synthesis of volatile terpenoids in snapdragon

“…Blue light reduces the expression of the AmPIF4 gene Light is the main factor affecting terpene emissions, and blue light signi cantly increased not only terpene emissions but also the expression of TPS genes (AmOCS and AmMYS ) compared with the green light, red light, dark, and normal treatments [17]. Moreover, expression of the terpenoid biosynthesisrelated genes AmDXS and AmDXR increased after exposure to blue light [40]. To investigate the role of PIF TFs in the regulation of blue light-induced terpenoid biosynthetic genes, six TFs were identi ed from the transcriptome data of different light treatments [17] against the reference genome http://bioinfo.sibs.ac.cn/Am/ [41].…”

“…To elucidate the upstream signaling pathway of blue light induction in the biosynthesis of oral terpenoid volatiles, the role of CRY1 was investigated. In AmCRY1-silencing owers, the expression of terpenoid biosynthesis genes is repressed, and terpenoid emissions are decreased [40]. However, the expression of AmPIF4 was decreased after blue light exposure but increased after AmCRY1 silencing, indicating that blue light inhibits its expression.…”

“…CRY2 interacts with CIB1 to inhibit its DNA-binding activity and regulate leaf senescence in soybean [68]. AmCRY1 interacts directly with AmMYB24 to increase its transcriptional activity in terpenoid biosynthesis [40]. Additionally, the MYB transcription factors PAP1 and PAP2 can interact with COP1 to regulate anthocyanin accumulation [69].…”

“…The petal volatile components of snapdragon and their content were assayed qualitatively and quantitatively by headspace solid-phase microextraction and GC-MS. Floral scent compounds were trapped and desorbed followed [40]. The volatiles were examined qualitatively by comparing the mass spectra and retention time with the NIST 2008 mass spectra library and standard samples.…”

Transcriptome analysis identifies key gene LiMYB305 involved in monoterpene biosynthesis in Lilium ‘Siberia’

“…AtMYB21/24 has been demonstrated to directly regulate the expression of terpene synthase genes, and the effect on linalool has been confirmed ( Yang et al., 2020 ). Snapdragon AmMYB24 interacts with AmCRY1 to activate AmOCS by binding to the MYBCOREATCYCB1 motif, thereby increasing the synthesis of ocimene ( Han et al., 2022 ). Therefore, we speculated that LiMYB305 directly binds and regulates terpene synthase.…”