College of Agriculture, Nanjing Agricultural University, Nanjing, 210095, PR China.
College of Agriculture, Nanjing Agricultural University, Nanjing, 210095, PR China; Department of Crop and Soil Sciences, University of Georgia, Tifton, GA, 31794, USA.
Plant Physiol Biochem. 2018 Sep;130:633-640. doi: 10.1016/j.plaphy.2018.08.010. Epub 2018 Aug 8.
Fruiting branches and floral buds are forming well before squares are visible and determine cotton (Gossypium hirsutum L.) productivity. Pre-soaking with plant growth regulators (PGRs) affects the quantity of floral buds. However, studies illustrating the physiological mechanism of floral bud differentiation in response to PGRs are lacking. To address this, cotton seeds were primed with water (control), 5 mg L gibberellic acid (GA), 25 mg L N6-benzyladenine (6-BA), and 150 mg L dimethyl piperidinium chloride (DPC) respectively. Results showed that plants from seed pre-treated with GA and 6-BA differentiated more floral buds relative to control, while DPC application initiated less floral buds than control. GA and 6-BA application significantly increased the levels of zeatin riboside (ZR) by up-regulating IPT expression and gibberellic acid (GA) but decreased the indole-3-acetic acid (IAA) content. Consequently, the ZR/IAA and GA/IAA ratios were markedly increased, contributing to higher floral bud numbers. Contrasting results were observed for DPC treatment. Additionally, GA and 6-BA treatments up-regulated GhSOC1, GhMADS13 and GhAGL24 expression, which was associated with higher sucrose contents mainly attributed to higher endogenous ZR levels, inducing floral initiation. Whereas the GhMADS13 was down-regulated to suppress floral bud differentiation under DPC application. Surprisingly, the floral-associated genes were more sensitive to GA than 6-BA, which induced the differences in bud numbers at the beginning of flower bud differentiation. Thus, we conclude that seed pre-treated with PGRs affected hormone content, induced sugar accumulation in apical buds and regulated genes involved in floral induction, which impacted floral bud differentiation.
生殖枝和花芽在出现可见的方块之前就已经很好地形成，这决定了棉花（Gossypium hirsutum L.）的生产力。植物生长调节剂（PGRs）的预浸泡会影响花芽的数量。然而，缺乏阐明 PGR 对花芽分化的生理机制的研究。为了解决这个问题，棉花种子分别用清水（对照）、5mg/L 赤霉素（GA）、25mg/L N6-苄基腺嘌呤（6-BA）和 150mg/L 二甲基哌啶氯化物（DPC）进行了预处理。结果表明，与对照相比，用 GA 和 6-BA 预处理的种子处理的植株分化出更多的花芽，而 DPC 的应用比对照启动的花芽更少。GA 和 6-BA 的应用通过上调 IPT 表达和赤霉素（GA）显著增加了玉米素核苷（ZR）的水平，但降低了吲哚-3-乙酸（IAA）的含量。因此，ZR/IAA 和 GA/IAA 比值显著增加，导致花芽数量增加。DPC 处理则观察到相反的结果。此外，GA 和 6-BA 处理上调了 GhSOC1、GhMADS13 和 GhAGL24 的表达，这与较高的蔗糖含量有关，主要归因于较高的内源性 ZR 水平，诱导花芽起始。而 GhMADS13 的下调抑制了 DPC 处理下的花芽分化。令人惊讶的是，与 6-BA 相比，GA 对花相关基因更敏感，这在花芽分化初期导致了芽数的差异。因此，我们得出结论，PGR 预处理的种子影响激素含量，诱导顶芽糖的积累，并调节参与花诱导的基因，从而影响花芽分化。
