VqMAPKKK38 is essential for stilbene accumulation in grapevine

Abstract

Vitis species, including grapevine, produce a class of secondary metabolites called stilbenes that are important for plant disease resistance and can have positive effects on human health. Mitogen-activated protein kinase (MAPK) signaling cascades not only play key roles in plant defense responses but also contribute to stilbene biosynthesis in grapevine. MAPKKKs function at the upper level of the MAPK network and initiate signaling through this pathway. In this study, a Raf-like MAPKKK gene, VqMAPKKK38, was identified and functionally characterized from the Chinese wild grapevine V. quinquangularis accession ‘Danfeng-2’. We observed that VqMAPKKK38 transcript levels were elevated by powdery mildew infection, high salinity conditions and chilling stresses, as well as in response to treatments by the hormones salicylic acid (SA), methyl jasmonate (MeJA), ethylene (Eth) and abscisic acid (ABA). In addition, based on both transient overexpression and gene suppression of VqMAPKKK38 in grapevine leaves, we found that VqMAPKKK38 positively regulates stilbene synthase transcription and stilbene accumulation probably by mediating the activation of the transcription factor MYB14. In addition, both hydrogen peroxide (H2O2) and calcium influx activated VqMAPKKK38 expression and stilbene biosynthesis, which suggests that VqMAPKKK38 may be involved in the calcium signaling and ROS signaling pathways.

Genome-wide identification of MAPKKK genes and their responses to phytoplasma infection in Chinese jujube (Ziziphus jujuba Mill.)

“…In wheat, a MAPKKK named TaFLR can be activated by the leaf rust pathogen Puccinia triticina [31]. In grapevine, VqMAPKKK38 can be highly induced by powdery mildew infection [32]. All the evidence suggests that members of MAPKKKs are essential in pathogen attack signal transduction.…”

Genome-wide identification of MAPKKK genes and their responses to phytoplasma infection in Chinese jujube (Ziziphus jujuba Mill.)

“…In wheat, a MAPKKK named TaFLR can be activated by the leaf rust pathogen Puccinia triticina [40]. While in grapevine, VqMAPKKK38 can be highly induced by powdery mildew infection [41]. All the evidence suggests the members of MAPKKKs are essential in pathogen attack signal transduction.…”

“…Meanwhile, in the sterile cultivated tissues of JWB plantlets, four ZjMAPKKKs (4, 10, 25 and 44) were significantly induced in the diseased plants. Also,ZjMAPKKK6,7,17,18,30,34,35,37,40,41,43,46,52…”

“…In the three main infected tissues (witches' broom leaves, phyllody leaves, apparently normal leaves), ZjMAPKKK26 and 45 were significantly up-regulated and ZjMAPKKK3, 43 and 50 were significantly down-regulated. While the ZjMAPKKK4, 10, 25 and 44 were significantly and highly induced in sterile cultivated tissues infected by phytoplasma, while ZjMAPKKK6, 7,17,18,30,34,35,37,40,41,43,46, 52 and 46 53 were significantly down-regulated.…”

Calcium- and hormone-driven regulation of secondary metabolism and cell wall enzymes in grape berry cells

“…These results highlight the intricate signaling pathways in which calcium is involved and the interplay with other signaling processes. Accordingly, recent studies demonstrated that calcium can modulate stilbene biosynthesis in Vitis, in mechanisms that require the involvement of calcium-dependent and mitogen-activated protein kinases (Aleynova et al, 2015;Jiao et al, 2017). Few studies on Arabidopsis, strawberry and grape also suggested a link between calcium and anthocyanins, where Ca 2+ , calmodulin, sugars, and protein kinases/phosphatases are key players, possibly by modulating anthocyanin biosynthetic genes (Vitrac et al, 2000;Shin et al, 2013;Xu et al, 2014;Peng et al, 2016;Zou et al, 2017).…”