Key message

Exogenous ABA increased the flowering rate and advanced the flower formation of “Fuji” apple cv. “Nagafu No.2” by promoting the accumulation of soluble sugar, glucose and sucrose, and also increased the activities of α-AMY and SPS.

Abstract

“Fuji” apple (Malus domestica Borkh) has a long vegetative growth phase and difficulty in flower induction, which seriously affects apple production. ABA plays important roles in the flower bud induction of fruit trees. However, the effect of exogenous ABA on flower bud induction of apple trees has rarely been reported. In this experiment, 2-year-old “Fuji” apple cv. “Nagafu No. 2” scion material was grafted on dwarf self-rooted rootstock M.26 (DSR), vigorous rootstock M. sieversii (VR) and interstock M.26/M. sieversii (IR). The control trees were sprayed with water solution, while 100 µmol·L⁻¹ ABA and 5 mmol·L⁻¹ sodium tungstate (ST) were applied as treatments. The results showed that exogenous ABA promoted flower formation and increased the flowering rate, but the impact on the VR was not obvious. Furthermore, the accumulation of soluble sugar, glucose and sucrose, as well as the activities of α-amylase (α-AMY) and sucrose phosphate synthase (SPS) in the leaves and buds were also significantly promoted. However, the starch concentrations and sucrose synthase (SS) activities decreased. The increase of leaf specific weight and decrease of the growth of single leaf area were supportive to the growth of flower buds. Linear relationships were discovered between starch concentration and α-AMY activity (R² = 0.998, p < 0.05), sucrose concentration and the activities of SS and SPS (R² = 0.854–0.999, p < 0.05). Besides, exogenous ST had negative effects compared with ABA. Exogenous ABA increased sugar metabolism, and enzyme activities of DSR, and also enhanced the absorption and utilization of sugar substances, resulting in easier flowering in the DSR, followed by the IR, except for the difficult-flowering rootstock VR. Finally, the expression levels of TPS7, PPC1 and ABR1 were up-regulated in leaves and buds after ABA application, while the floral inhibiting gene TFL1 was down-regulated, indicating that exogenous ABA may promote flower bud differentiation by inhibiting TFL1 expression in apple.

中文翻译：

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外源ABA及其抑制剂调节苹果cv花芽的诱导。'Nagafu No.2'嫁接到不同的砧木上

关键信息

外源ABA提高了“富士”苹果cv的开花率并促进了花的形成。Nagafu No.2通过促进可溶性糖，葡萄糖和蔗糖的积累，并增加了α-AMY和SPS的活性。

抽象

苹果（Fusus domestica Borkh）营养生长期长，诱导花困难，严重影响了苹果的产量。ABA在果树的花芽诱导中起重要作用。然而，很少报道外源ABA对苹果树花芽诱导的作用。在这个实验中，2岁的“富士”苹果简历。将“ Nagafu No.2”接穗材料嫁接到矮生的自根砧木M.26（DSR），旺盛的砧木M. sieversii（VR）和中间砧木M.26 / sieversii（IR）上。对照树上喷洒100 µmol·L ^-1 ABA和5mmol·L ^-1的水溶液。钨酸钠（ST）用作治疗剂。结果表明，外源ABA促进花的形成并提高开花率，但对VR的影响不明显。此外，还显着促进了叶和芽中可溶性糖，葡萄糖和蔗糖的积累，以及α-淀粉酶（α-AMY）和蔗糖磷酸合酶（SPS）的活性。但是，淀粉浓度和蔗糖合酶（SS）活性下降。叶比重的增加和单叶面积的增长的减少都支持花蕾的生长。发现淀粉浓度与α-AMY活性（R ²  = 0.998，p  <0.05），蔗糖浓度与SS和SPS活性（R ²  = 0.854–0.999，p  <0.05）。此外，外源性ST与ABA相比具有负面作用。外源ABA增加了糖代谢和DSR的酶活性，还增强了糖类物质的吸收和利用，导致DSR中较难开花的根茎VR除外，在DSR中较易开花，其次是IR。最后，ABA处理后叶片和茎中TPS7，PPC1和ABR1的表达水平上调，而抑制花的基因TFL1被下调，表明外源ABA可能通过抑制苹果中TFL1的表达促进花芽分化。