The Effect Of MYB14 On The Stilbene Synthesis Triggered By Al³⁺ And UV-C In Vitis ‘Cabernet Sauvignon' And ‘Concord'

Grapevine is an important fruit crop all over the world,but its production is often limited by pathogen infection.Stilbenes,a class of secondary metabolite derived from the phenylpropanoid pathway,represent phytoalexins that contribute to defence against pathogens in plants.The main antibacterial ingredient of stilbenes is resveratrol.It is known that the transcription factors MYB14 and MYB15 are required for the activation of resveratrol synthase,and they are one of the necessary regulatory factors for biosynthesis of stilbenes.In the current study,we observed that stilbene levels were more highly induced by short time UV-C radiation and 1%Al³⁺treatments in the cultivar Vitis labrusca‘Concord'than in the cultivar V.vinifera‘Cabernet Sauvignon',and this difference is relative with the expression level of MYB14.We further analyzed the promoter regions of MYB14 and MYB15 from two genotypes,and significant differences were found in MYB14 between the two genotypes,while MYB15 has a similarity of 99%.On this basis,we conducted an in-depth study on the promoter function of MYB14.The promoter activity of MYB14 was measured in heterologous expression Nicotiana benthamiana system:we found that the activity of pVlMYB14?the promoter of Concord?was significantly increased by Al³⁺and UV-C treatment,and ROS,Ca²⁺and MPAKs played key regulatory roles in the activation of pVlMYB14.Meanwhile,DPI,an inhibitor of NADPH oxidase,could significantly reduce the accumulation of stilbenes after Al³⁺and UV-C treatments.Based on these results,this study proposed a signaling pathway model for the accumulation of stilbenes in Concord induced by Al³⁺and UV-C in this process,ROS play a key regulatory role in the activation of MYB14 and the synthesis of stilbenes,in which,Ca²⁺and MAPK pathways are involved as well.