AtMYB12 regulates caffeoyl quinic acid and flavonol synthesis in tomato: expression in fruit results in very high levels of both types of polyphenol

Abstract

SummaryPlant polyphenolics exhibit a broad spectrum of health-promoting effects when consumed as part of the diet, and there is considerable interest in enhancing the levels of these bioactive molecules in plants used as foods. AtMYB12 was originally identified as a flavonol-specific transcriptional activator in Arabidopsis thaliana, and this has been confirmed by ectopic expression in tobacco. AtMYB12 is able to induce the expression of additional target genes in tobacco, leading to the accumulation of very high levels of flavonols. When expressed in a tissue-specific manner in tomato, AtMYB12 activates the caffeoyl quinic acid biosynthetic pathway, in addition to the flavonol biosynthetic pathway, an activity which probably mirrors that of the orthologous MYB12-like protein in tomato. As a result of its broad specificity for transcriptional activation in tomato, AtMYB12 can be used to produce fruit with extremely high levels of multiple polyphenolic antioxidants. Our data indicate that transcription factors may have different specificities for target genes in different plants, which is of significance when designing strategies to improve metabolite accumulation and the anti-oxidant capacity of foods.

Retracted: Nitric oxide enhances plant ultraviolet‐B protection up‐regulating gene expression of the phenylpropanoid biosynthetic pathway

“…Among the R2R3 MYB, it has been demonstrated that the maize P gene (ZmP) and its Arabidopsis functional homolog MYB12 control the transcriptional activation of the phenylpropanoid biosynthetic genes chalcone synthase (CHS), chalcone isomerase (CHI), flavonone 3-hydroxylase (F3H) and flavonol synthase 1 (FLS1) (Grotewold 2005;Mehrtens et al 2005;Luo et al 2008). Furthermore, it was reported that ZmP as well as MYB12 are up-regulated by UV-B exposure (Casati & Walbot 2005;Oravecz et al 2006).…”

A Visual Reporter System for Virus-Induced Gene Silencing in Tomato Fruit Based on Anthocyanin Accumulation

“…The target gene regulation of specific myb genes cannot always be directly translated from one plant species to another based on sequence homology, as has been repeatedly observed (Martin and Paz-Ares, 1997;Mehrtens et al, 2005;Luo et al, 2008). ODO1 VIGS in petunia resulted in lower levels of almost all analyzed benzenoid compounds.…”

Do Transcription Factors Play Special Roles in Adaptive Variation?

“…Purugganan and Fuller (2009) have claimed that domestication of crops involves predominantly changes in transcriptional activators operating in transcriptional networks. For engineering metabolism through biotechnological approaches, it has already been shown that engineering lower-order TFs is a very effective means of increasing flux to secondary metabolites of interest without incurring massive pleiotropic effects (Grotewold et al, 1998;Bovy et al, 2002;Butelli et al, 2008;Luo et al, 2008;Zhang et al, 2009). Perhaps the most effective way to engineer other traits will be to focus on similar lower-order regulators of cell development and metabolism (Martin, 1996;Broun and Somerville, 2001).…”