Heterologous Overexpression Of Resveratrol Synthase Gene (PcPKS5) Enhances Antifungal And Mite Aversion By Resveratrol Accumulation With Agrobacterium Mediated Transformation System Of Juiube (Zizvphus Iujuba Mill.)

Jujube (Ziziphus jujuba Mill.) is an important crop species that originated in China. Huping jujube is widely cultivated as one of the best Chinese jujube varieties. Huping jujubes are especially found in the Shanxi Province; they are valued for their large size, thin skin, and sweet flavor. These plants are also frequently cultivated in China due to unique traits such as strong resistance to bad climate and environment, fast-growth, high nutritional content, and other economic and ecological benefits. However, Huping jujube yield and quality are severely affected by fruit dehiscence, heavy fruit drop, and difficulties associated with storage and transportation.Studies have shown that diseases have seriously hindered the global development of the jujube industry since the late 1970s. Indeed, nine fungal and four bacterial genera were found to be involved in several diseases such as anthrax, tin disease, black spot, rot disease, pulp rot disease, black boil disease, and ring rot disease (Wei, et al,2006). Due to jujube’s economic value and the difficulty of its improvement through traditional plant breeding approaches, genetic transformation techniques may have great potential to provide a means for transferring one or more selected desirable traits into the plant’s genome to anti-environmental stress.Recently, the stilbene synthase gene (PcPKSS) was isolated from Polygonum cuspidatum roots, where it caused high accumulation of resveratrol (GUO et al,2013). PcPKS5, PcPKS1 and PcPKS3 belong to the same CHS family of genes. PcPKS5 was the first three-intron STS gene reported in flowering plants. Its enzymatic product was identified as resveratrol (Km=8.5, comparison with Naringenin Km=l.6), and the protein has been confirmed to participate in the biosynthesis pathway of resveratrol (Ma et al,2009a,2009b; Guo et al,2013).Here, PcPKS5 was overexpressed under the control of the CaMV 35S promoter in Huping Jujube, and the resulting transgenic plants showed increased resveratrol accumulation and enhanced mite resistance. Our results suggest that disease resistance and fruit quality of the jujube plant could be improved via heterologous PcPKS5 introduction, also providing new tools for improving commercial development of Huping Jujube. This study aimed to assess the effects of heterologous overexpression of the resveratrol synthase (PcPKS5) gene on Huping jujube (Ziziphus jujuba Mill.) plant resistance and nutritional quality. The results included:(1) Optimization of regeneration system are bothe cluster buds induction on Huping jujube and bud induction from callus of Goutou jujube leaf.(2) Establishment of genetic transformation system on Huping jujube. Stems with leaves and shoot tips of Huping jujube (Ziziphus jujuba Mill) were infected with agrobacterium expressing PcPKS5 and GUS.(3) Three positive plants were identified. Resveratrol (0.45 μg/g fresh weight) was detected by HPLC in line 2 transgenic plants.(4) 100 μl extract of 1 g/mL transgenic plant crude extract showed an inhibitory effect equivalent to 1.0 μg of pure resveratrol, resisstance to Monilinia fructicola^ Isariopsis imdica var. Ziziphi、Alternaria alternate(Fr.)Keissler.In addition, transgenic plants increased anti-mite resistance compared with the wild-type counterparts. Importantly, higher PcPKS5 expression levels were found in young tissues compared with the stem and mature leaves. This study also provides a stable genetic transformation mechanism for developing new plant germplasms in Huping jujube.