Mechanism Of Salicylic Acid Regulating Flavan-3-ols Accumulation Induced By VvMYBPA1/PA2 In Grape Leaves

The new shoot leaves of ‘Zao Hei Bao’ grape were used as materials,and virus-induced gene silencing(VIGS)technology was used to silence VvANR,VvLAR2,VvMYBPA1,VvMYBPA2,VvMYBPA1 and VvMYBPA2 respectively.SA incubation was carried out after silencing in order to explore the accumulation rule and mechanism of flavan-3-ols in grape leaves induced by exogenous salicylic acid(SA).The results show that:(1)0.5 mmol·L-1 exogenous SA promoted the accumulation of free SA,total phenols,total flavonoids,total flavan-3-ols and flavan-3-ol monomer in ‘Zao Hei Bao’ grape leaves,it induced the increase of ANR and LAR enzyme activities,and it promoted the transcription of VvANR,VvLAR1,VvLAR2,VvMYBPA1 and VvMYBPA2 genes related to flavan-3-ols biosynthesis.(2)After VvANR and VvLAR2 were silenced,the expression of VvANR and VvLAR2 in grape leaves decreased significantly,and the activity of ANR enzyme decreased.After silencing,SA incubation promoted the accumulation of flavan-3-ols in leaves.The activities of ANR and LAR enzymes increased significantly at 10 min.The expression of VvANR and VvLAR2 increased significantly at 10 min after incubation.Exogenous SA can promote the activities of ANR and LAR enzymes in grape leaves silenced by VvANR and VvLAR2 or activate the expression of VvANR and VvLAR2 genes,thus it inducing the accumulation of flavan-3-ol monomer.(3)After VvMYBPA1 and VvMYBPA2 were silenced,the expression of VvMYBPA1 and VvMYBPA2 decreased significantly in grape leaves,and the activities of ANR and LAR enzymes and the content of flavan-3-ol monomer decreased.SA incubation promoted the accumulation of flavan-3-ols in leaves after silencing.The activities of ANR and LAR enzymes increased.The expression of VvMYBPA1 was significantly up-regulated,while the expression of VvMYBPA2 was up-regulated but the difference was not significant.Exogenous SA promoted the activities of ANR and LAR enzymes silenced by VvMYBPA1 and VvMYBPA2,thus promoting the accumulation of flavan-3-ol monomer in grape leaves.SA promotes the expression of VvMYBPA1 and VvMYBPA2 genes silenced by VvMYBPA1 and VvMYBPA2,thus promoting the accumulation of flavan-3-ols substances.(4)After VvMYBPA1 and VvMYBPA2 were co-silenced,the expression of VvMYBPA1 and VvMYBPA2,the activities of ANR and LAR enzymes and the content of flavan-3-ol monomer decreased significantly in grape leaves.SA incubation promoted flavan-3-ols accumulation in leaves after silencing.The activities of ANR and LAR enzymes increased significantly.The expression of VvMYBPA1 and VvMYBPA2 increased significantly from 10 to 30 min and 10 min respectively.Exogenous SA promoted the activities of ANR and LAR enzymes co-silenced by VvMYBPA1 and VvMYBPA2,thus promoting the synthesis of flavan-3-ol monomer in grape leaves.SA can promote the expression of VvMYBPA1 or VvMYBPA2 silenced by VvMYBPA1 and VvMYBPA2,and then it can promote the accumulation of flavan-3-ol monomer.And SA promoted the expression of VvMYBPA1 more than VvMYBPA2 in the co-silence of VvMYBPA1 and VvMYBPA2.