外源葡萄糖对‘长富2号’苹果花芽生理分化期可溶性糖和相关基因表达的影响

以‘长富2号’苹果为材料,于花后25和30 d喷施浓度1.5%和3%的葡萄糖,研究处理后短枝顶芽的发育状况、可溶性糖、淀粉含量及相关代谢酶活性的动态变化,并利用实时荧光定量PCR检测糖代谢相关基因与成花相关基因的表达模式。结果表明:葡萄糖处理后,短枝顶芽长度、宽度及质量有一定程度增加;短枝顶芽中,蔗糖、葡萄糖、山梨醇在生理分化中前期显著高于对照,淀粉含量整体升高,而果糖含量在整个生理分化期显著降低;山梨醇脱氢酶、山梨醇氧化酶、蔗糖合酶合成方向以及蔗糖磷酸合成酶活性在不同时期有所增加,而酸性与中性蔗糖转化酶,及蔗糖合酶分解方向酶活性普遍降低;叶片中碳水化合物积累明显,糖代谢相关酶活性也发生相似改变;顶芽糖代谢相关基因及2个MdTPS基因都响应葡萄糖处理;成花关键基因MdFT 1、MdFD、MdLFY、MdSOC 1和MdAP 1均显著上调,而成花抑制基因MdTFL 1从花后30 d开始,表达显著下调。

Effects of Exogenous Glucose Treatment on Soluble Sugar and Expression of Related Genes During Floral Bud Differentiation Stage in Terminal Spur Buds of‘Nagafu 2’Apple

‘Nagafu 2’apple trees were sprayed with 1.5% and 3% glucose solutions at 25 days and 30 days after full bloom，respectively. Bud growth，endogenous sugar levels，starch content and activities of related enzymes in terminal spur buds were examined. Genes associated with sugar metabolism and flowering were studied by quantitative real-time PCR. The results revealed that glucose treatments increased bud size and fresh weight. The contents of sucrose，glucose and sorbitol were significantly higher than in the control during early stage of floweral bud differentiation，while starch increased generally，but the content of fructose significantly decreased during the whole period. The activities of sorbitol dehydrogenase，sorbitol oxidase，synthesis direction of sucrose synthase and sucrose phosphate synthase increased at different stages，while acid and neutral invertases，decomposition direction of sucrose synthase decreased. Carbohydrate accumulation in leaves was evident，and the activities of enzymes involved in sugar metabolism also changed similarly. Genes associated with sugar metabolism and two MdTPS genes in terminal buds all responded to glucose treatment. Furthermore，flowering genes like MdFT 1，MdFD，MdLFY，MdSOC 1，and MdAP 1 were significantly up-regulated，while the suppressor MdTFL 1 was down-regulated from beginning of floral induction.