Abstract:

In the present study，using strawberry cultivar‘Toyonaka’（Fragaria × ananassa） as plant materials，we silenced the gene encoding FaMYB5 transcription factor，which was imparted in flavonoid metabolism in fruits of strawberry by using Virus-induced gene silencing（VIGS）technology. After silencing of FaMYB5，the expression level of other important genes involved in flavonoid metabolic pathway was detected by semi-quantatitive PCR and RT-qPCR. Meanwhile，in order to fully investigate the role of FaMYB5 in regulating the flavonoid metabolic pathway，we determined the anthocyanins and proanthocyanidins content using HPLC and DMACA chemical methods respectively. The results showed that，the recombined pTRV2-FaMYB5 vector and the VIGS system were successfully constructed. By determining of the phenotype and detecting the expression of FaMYB5 after its silencing，the efficiency of gene silencing was about 60%. In constract with the negative control group，the expression of FaMYB9，FaLAR，FaDFR，and FaANR increased，leading to an increasing of proanthocyanidins level. On the contrary，half of the expression level was observed for FaANS，accompanied with the anthocyanins decreasing. While the expression of FaMYB10 had no radical change. In addition，the expression of FabHLH3 and bHLH3Δ decreased after silencing of FaMYB5. However，the expression of FaGL3 had an obvious increasing phase. All the results showed that FaMYB5 transcription factor could negatively regulate the proanthocyanidins metabolism pathway.

Key words: strawberry, VIGS, FaMYB5, negatively regulation, flavonoids metabolism