Ning Ya, Chen Yuchun, He Xiyong, Yang Tingmei, Yue Hai
Yunnan Institute of Tropical Crops, Xishuangbanna 666100, China.
Macadami Agricultural Engineering Research Center of Yunnan Province, Xishuangbanna 666100, China.
Plants (Basel). 2025 Aug 24;14(17):2637. doi: 10.3390/plants14172637.
Off-season flowering of Macadamia integrifolia has been observed in certain high-altitude regions; however, the endogenous hormonal mechanisms underlying this phenomenon remain unclear. In this study, the annual dynamics of four key endogenous phytohormones (ZT, GA, IAA, and ABA) were quantified in the leaves and branches of trees from both normal and off-season flowering sites using high-performance liquid chromatography (HPLC). Hormonal ratios and correlation network analyses were further performed to investigate their roles in flowering regulation. Floral bud differentiation at the off-season site occurred approximately 1 to 2 months earlier than at the normal site. This advancement was associated with sustained low levels of GA (below 100 μg·g FW), while ZT and ABA levels peaked in September at 108.66 μg·g FW and 24.25 μg·g FW, respectively. The ratios of ABA to GA, ABA to IAA, and ZT to GA increased significantly between July and September, indicating the early establishment of a hormonal environment favorable for floral induction. Correlation analysis revealed that IAA, GA, and ZT formed a synergistic module promoting flowering, whereas ABA functioned as an antagonistic regulator. These findings provide insight into the hormonal regulation of off-season flowering in macadamia and offer a theoretical basis for precision flowering control in high-altitude cultivation systems.
在某些高海拔地区已观察到澳洲坚果的反季节开花现象；然而，这种现象背后的内源激素机制仍不清楚。在本研究中，使用高效液相色谱法（HPLC）对正常开花和反季节开花地点树木的叶片和枝条中四种关键内源植物激素（玉米素（ZT）、赤霉素（GA）、生长素（IAA）和脱落酸（ABA））的年度动态进行了定量分析。进一步进行了激素比率和相关网络分析，以研究它们在开花调控中的作用。反季节开花地点的花芽分化比正常开花地点早约1至2个月。这种提前与GA持续处于低水平（低于100μg·g FW）有关，而ZT和ABA水平分别在9月达到峰值，为108.66μg·g FW和24.25μg·g FW。7月至9月期间，ABA与GA、ABA与IAA以及ZT与GA的比率显著增加，表明有利于成花诱导的激素环境提前建立。相关性分析表明，IAA、GA和ZT形成了一个促进开花的协同模块，而ABA起到拮抗调节作用。这些发现为澳洲坚果反季节开花的激素调控提供了见解，并为高海拔栽培系统中的精准开花控制提供了理论依据。
