Spearmint R2R3‐ MYB transcription factor Ms MYB negatively regulates monoterpene production and suppresses the expression of geranyl diphosphate synthase large subunit ( Ms GPPS . LSU )

• Published in: Plant biotechnology journal 2017-09, Vol.15 (9), p.1105-1119
• Main Authors: Reddy, Vaishnavi Amarr, Wang, Qian, Dhar, Niha, Kumar, Nadimuthu, Venkatesh, Prasanna Nori, Rajan, Chakravarthy, Panicker, Deepa, Sridhar, Vishweshwaran, Mao, Hui‐Zhu, Sarojam, Rajani
• Format: Article
• Language: English
• ISSN: 1467-7644; 1467-7652
• DOI: 10.1111/pbi.12701

Many aromatic plants, such as spearmint, produce valuable essential oils in specialized structures called peltate glandular trichomes ( PGT s). Understanding the regulatory mechanisms behind the production of these important secondary metabolites will help design new approaches to engineer them. Here, we identified a PGT ‐specific R2R3‐ MYB gene, Ms MYB , from comparative RNA ‐Seq data of spearmint and functionally characterized it. Analysis of Ms MYB ‐ RNA i transgenic lines showed increased levels of monoterpenes, and Ms MYB ‐ overexpressing lines exhibited decreased levels of monoterpenes. These results suggest that Ms MYB is a novel negative regulator of monoterpene biosynthesis. Ectopic expression of Ms MYB , in sweet basil and tobacco, perturbed sesquiterpene‐ and diterpene‐derived metabolite production. In addition, we found that Ms MYB binds to cis ‐elements of Ms GPPS . LSU and suppresses its expression. Phylogenetic analysis placed Ms MYB in subgroup 7 of R2R3‐ MYB s whose members govern phenylpropanoid pathway and are regulated by miR858. Analysis of transgenic lines showed that Ms MYB is more specific to terpene biosynthesis as it did not affect metabolites derived from phenylpropanoid pathway. Further, our results indicate that Ms MYB is probably not regulated by miR858, like other members of subgroup 7.