Ectopic expression of VlmybA1 in grapevine activates a narrow set of genes involved in anthocyanin synthesis and transport

Abstract

The colour of the red wine is essentially due to the release of anthocyanins from the red skin of grape berries during the process of wine making. Anthocyanins are synthesized during ripening of the berries under the control of VvMYBA1 transcription factor that controls the expression of UFGT. In order to identify the whole set of downstream regulated genes, we targeted constitutive ectopic expression of VlmybA1-2 into grapevine hairy roots and plants. The ectopic expression of VlmybA1-2 triggered de novo production and storage of anthocyanins in all transgenic vegetative organs, leading to a very intense red coloration, and did not interfere with proanthocyanidin (PA) biosynthesis. The ectopic red pigmentation was due to the accumulation of anthocyanins in vacuoles and anthocyanin vacuolar inclusion (AVIs) in all organs but only in specific tissues. A transcriptomic analysis using a 14 K oligoarray revealed that the ectopic expression of VlmybA1-2 activated only few genes, most of which are involved in both PA and anthocyanin biosynthesis, while the expression of BAN and LAR (two specific genes of the PA biosynthesis pathway) was unaffected. Among these, 4 genes emerged given the amplitude of their up-regulation, quantitatively similar to VlmybA1-2 itself. In addition to the previously described UFGT, this set comprised an isogen of GST, an O-methyltransferase, both of which are supposed to play a role in the anthocyanin biosynthesis pathway, as well as a candidate gene putatively involved in the vacuolar anthocyanin transport in grapevine (anthoMATE). Together, these results suggest that MybA1 activates the last steps of anthocyanin synthesis and transport through the regulation of a narrow, specific spectrum of genes regulated as a cluster.

ABCC1, an ATP Binding Cassette Protein from Grape Berry, Transports Anthocyanidin 3-O-Glucosides

“…To further investigate and validate the mechanism indicating that GSH is required for anthocyanin transport, we used a transgenic anthocyanin-producing HR system (Cutanda-Perez et al, 2009). In this system, grapevine HRs transformed with the transcription factor Vv-MYBA1 exhibit a constitutive synthesis and accumulation of anthocyanins.…”

“…Grapevine HRs producing anthocyanins were generated from Tempranillo, Portan, and Syrah plantlets and are described by Cutanda-Perez et al (2009). Culturing of the transgenic HRs was performed as described by Torregrosa and Bouquet (1997) with the modifications reported by Cutanda-Perez et al (2009).…”

“…Culturing of the transgenic HRs was performed as described by Torregrosa and Bouquet (1997) with the modifications reported by Cutanda-Perez et al (2009). Stable HR lines were grown on solidified LGO medium (Cutanda-Perez et al, 2009; LGO as described in Torregrosa and Bouquet, 1997) and subcultured every 4 to 5 weeks until use.…”

“…Culturing of the transgenic HRs was performed as described by Torregrosa and Bouquet (1997) with the modifications reported by Cutanda-Perez et al (2009). Stable HR lines were grown on solidified LGO medium (Cutanda-Perez et al, 2009; LGO as described in Torregrosa and Bouquet, 1997) and subcultured every 4 to 5 weeks until use. Prior to phenotyping anthocyanin concentration and profile, 4-to 5-week-old HRs were exposed to LGO medium containing various concentrations of BSO for 14 d. (B) Anthocyanin-producing Tempranillo HRs were grown on increasing concentrations of BSO, a compound that inhibits glutamyl-Cys synthetase, the enzyme responsible for the first step of GSH biosynthesis.…”

The Grapevine Root-Specific Aquaporin VvPIP2;4N Controls Root Hydraulic Conductance and Leaf Gas Exchange under Well-Watered Conditions But Not under Water Stress

“…Nevertheless, significant advances have recently been made in the development of transgenic technology, and transgenic plants from commercially important cultivars have been produced (Reustle and Büchholz, 2009). However, the genetic transformation of grapevine has been mainly focused on enhancing disease resistance against pathogens, and only a few studies aimed at elucidating the functions of endogenous genes have been carried out to date (Tesnière et al, 2006;Cutanda-Perez et al, 2009).…”