Chilling requirement and related gene expression analysis during dormancy release of Queen Nina grape

Abstract

[Objective] The purpose of the study was to analyze the chilling requirement and related gene expression during dormancy release of Queen Nina grape, so as to provide a theoretical reference for the introduction and promotion of Queen Nina grape in Guangxi grape producing areas and the study of its dormancy release mechanism.

[Method] Three-year-old Queen Nina grapes were used as experimental materials, and the 0-7.2 °C estimation model was used. The post-harvest pruning branches were treated at (4±1) °C for four different chilling treatment times of 0, 312, 408 and 504 h. The germination rate of branches treated with different chilling treatment times was calculated by hydroponic investigation, and the range of chilling requirement was determined by comparing the germination rate of branches treated with 3% hydrogen cyanamide dormancy breaker. The contents of total soluble sugar and starch in branches of each treatment were determined. The relative expression of five key genes for dormancy release was determined by real-time fluorescence quantitative PCR.

[Result] After 312 h of chilling treatment, the germination rate of Nina Queen grape was higher than 50% after 4 weeks of hydroponic culture, and there was no significant difference in the germination rate between all of them and that of the same chilling treatment sampled and then treated with hydrogen cyanamide ( P>0.05). In addition, the chilling accumulation hours of 0~7.2 °C under natural conditions before sampling were 37 h. Therefore, by adding the chilling treatment time to the natural accumulation of chilling hours, the chilling requirement could be estimated to be<349 h. During the dormancy release process of Queen Nina grape buds, the starch content in the branches significantly decreased ( P<0.05, the same below), and starch was converted into soluble sugars, with a significant increase in soluble sugar content. Compared with those without chilling treatment (0 h), the relative expression of the four key genes, including abscisic acid (ABA) synthase gene VvNCED1, ABA degrading enzyme gene VvA8H4, ABA regulated callose synthase gene VvCALS1 and callose hydrolase gene VvGLU1, significantly increased in Queen Nina buds after chilling treatment, while the relative expression of ABA synthase gene VvXERICO significantly decreased.

[Conclusion] Chilling treatment can release bud dormancy by reducing starch content, increasing the total soluble sugar content in the branches of Queen Nina grape, and further up-regulating the expression of ABA degrading enzyme genes and callose hydrolase genes in the buds of the grape. Queen Nina grape is a low chilling requirement variety, which is suitable for planting in Guangxi grape producing area.

Abstract

摘要：【目的】 分析妮娜皇后葡萄需冷量及休眠解除过程中相关基因表达, 为该品种在广西葡萄产区引种推广及 其休眠解除机制的研究提供理论参考。 【方法】以3年生妮娜皇后葡萄为试验材料, 采用0~7.2 °C估算模型, 对采后修 剪枝段进行 (4±1) °C下0、312、408和504 h共4个不同时长的低温处理, 通过水培调查计算各低温时长处理枝段萌芽 率。并对比3%浓度单氰胺破眠剂处理下的枝段萌芽率确定其需冷量范围; 测定各处理枝段中可溶性总糖与淀粉含 量; 通过实时荧光定量PCR检测芽内5个芽休眠解除关键基因的相对表达量。 【结果】妮娜皇后葡萄低温处理312 h后, 水培4周萌芽率均高于50%, 且均与相同低温处理取样后进行单氰胺处理的萌芽率无显著差异 ( P>0.05), 结合采样前 自然条件下0~7.2 °C的低温积累时数37 h, 将低温处理时间与自然积累的低温时数相加估算其需冷量<349 h;妮娜皇 后葡萄芽休眠解除过程中, 枝条中的淀粉含量显著降低 ( P<0.05, 下同), 淀粉转化为可溶性糖, 可溶性糖含量显著增 加。与未经低温处理 (0 h) 相比, 低温处理后妮娜皇后芽中脱落酸 (ABA) 合成酶基因 VvNCED1、ABA降解酶基因 VvA8H4、ABA调节的胼胝质合成酶基因 VvCALS1和胼胝质水解酶基因 VvGLU1等4个关键休眠基因的相对表达量均 显著增加, ABA合成酶基因 VvXERICO相对表达量显著降低。 【结论】低温处理能通过降低妮娜皇后葡萄枝条中淀粉 含量, 增加可溶性总糖含量, 并进一步上调葡萄芽内ABA降解酶基因和胼胝质水解酶基因的表达解除芽休眠。妮娜 皇后葡萄为低需冷量品种, 适宜在广西葡萄产区种植。