外源6-BA对‘美乐’葡萄花色苷合成的影响

Effects of exogenous 6-BA on anthocyanin synthesis in ‘Merlot’ grape

【目的】探究6-BA对葡萄花色苷合成的影响。【方法】以酿酒葡萄’美乐’为试材,喷施不同浓度的6-BA,以喷施清水为对照,研究6-BA对花色苷含量、组分及其生物合成途径相关基因表达的影响。【结果】100和200 mg·L^-16-BA处理提高了果实着色百分率和内源激素ABA的含量,其中200 mg·L^-1处理促进了花青素的积累,其含量是对照组的4.82倍,相关性分析表明200 mg·L^-1处理组的蔗糖与花色苷含量呈显著正相关。100和200 mg·L^-16-BA处理组的葡萄果实CHS1、F3’H、F3’5’H和UFGT基因的表达量在花后90 d显著提高,6-BA处理组通过影响F3’H和F3’5’H基因的表达量来影响不同花色苷的含量,从而影响果皮色泽。【结论】在果实着色后期,低质量浓度的6-BA通过提高内源激素ABA、可溶性总糖的含量以及相关基因的表达量,促进了花色苷的积累,其中200 mg·L^-16-BA处理效果更佳。

【Objective】Anthocyanin, a water-soluble pigment with antioxidant activity, is one of the crucial components for the red wine and table grape. It has a role in adaptation to adverse conditions and resistance to diseases. The climatic conditions have important impact on grape quality. In recent years,the wine grape industry has developed rapidly in Ningxia with favorable climate condition and geographical resources suitable for producing high-quality grapes. However, there is a problem of insufficient accumulation of anthocyanins and their derivatives due to the climate reasons in some regions.Plant grows regulators are applied to improve grape quality. The purpose of this study was to analyze the mechanism of the effect of 6-benzyladenine(6-BA), a synthetic cytokinin, on anthocyanin accumulation.【Methods】The experiment was conducted with seven-year-old vines of Vitis vinifera’Merlot’from 2016 to 2017 in Yuquanying Farm, Ningxia, where the soil in this region is typically sandy and the vineyard was planted in east-west lines. The plant spacing was 0.5 m×0.3 m and drip irrigation was adopted. The test set three 6-BA treatments with different concentrations: 100 mg · L^-1, 200 mg · L^-1 and400 mg· L^-1, and spraying distilled water served as the control. The sprays were made on the 50 th day after flowering on the clusters until drip-off. Berries were sampled five times from veraison to harvest.The samples were quickly frozen with liquid nitrogen and stored in a-80 ℃ freezer. Liquid chromatography was used separate the components. Chromatography is used to analyze the content of endogenous hormone ABA, which plays a critical role in the process of plant physiology and biochemistry. Anthocyanin quantity and composition were detected by spectroscopy and HPLC. Chemical analysis, HPLC analysis and transcriptional analysis were used to study the effect of 6-BA on the anthocyanin biosynthesis. qRT-PCR was carried out to quantify the expression levels of structural genes in the anthocyanin biosynthesis pathway including CHS1, F3’H, F3’5’H and UFGT.【Results】The results showed that different concentrations of 6-BA had an effect on the synthesis of anthocyanins. The treatment of 200 mg· L^-16-BA promoted fruit coloration and increased endogenous ABA content. The anthocyanin content in the treatment at 100 mg · L^-1(5.21 mg · g^-1), was higher than the control at 110 days after flowering. The results indicated that 6-BA 200 mg · L-1 treatment significantly increased the cyanidin-3-acelylglucoside content at mature stage, which was 4.82 times that of the control. Low concentration of 6-BA showed effect on the expression of anthocyanin synthesis related genes at version and the initial maturation stages.Among them, the expression levels of CHS1, F3’H and F3’5’H genes were increased mainly at veraison. Compared with the control, the 100 mg · L^-1 treatment significantly increased the relative expression of CHS1 at 90 days after flowering. The changes in the ratio of delphinidin-3-acelylglucoside to cyanidin-3-acelylglucoside were associated with the ratio of the expression of F3’5’H gene to that of F3’H gene expression. The expression of both F3’H and F3’5’H gene was up-regulated at 70 days after flowering in the 100 mg · L^-1 treatment, and in the 200 mg · L^-1 treatment, the relative expression of F3’5’H gene was 2.34 times that of the control. The expression level of the UFGT gene was increased in the initial maturation period by 6-BA treatments at the two concentrations(17.29 and 5.87 times that of the control, respectively). However, anthocyanin content in the 400 mg · L^-1 treatment was lower than the control throughout fruit ripening. Besides, this treatment not only delayed coloration, but also inhibited the expression of genes related to anthocyanin synthesis. Furthermore, the correlation analysis displayed a significant positive correlation between sucrose and anthocyanin content in 200 mg · L^-1 treatment.【Conclusion】At the late stage of veraison, low concentration of 6-BA promoted the accumulation of anthocyanins by increasing endogenous ABA, total soluble sugar content and the expression of related genes. Thus, ABA, sugars and the relevant genes play important roles in grape quality formation and low concentrations of 6-BA(100-200 mg · L^-1) has an effect in the improvement of fruit quality and the accumulation of anthocyanins in’Merlot’grape.