Paphiopedilum orchids have a high ornamental value, whose flower abundance and timing are both key horticultural traits regulated by phytohormones. All one-flowered Paphiopedilum have additional lateral buds in the apical bract that fail to develop. In this study, an exogenous GA3 application promoted flowering of Pycnogonum callosum by inducing its early bolting instead of the floral transition of dominant flowers. Applying GA3 effectively promoted lateral flower differentiation, resulting in a two-flowered inflorescence. GA-promoted of lateral flower formation involved GA interacting with indole-3-acetic acid (IAA) and cytokinins (CTKs), given the decreased CTK content and down-regulated expression of CTK synthesis genes, the increased IAA content and down-regulated expression of IAA degradation, and the up-regulated expression of transport genes. Further, GA acted via PcDELLA, PcTCP15, and PcXTH9 expressed in stage 5 to promote bolting, and via expression of PcAP3, PcPI, and PcSEP to promote flowering. This study provides insight into mechanisms regulating flower development of P. callosum.

中文翻译：

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外源GA3通过抽薹和侧花发育调控促进胼胝科植物开花

兜兰具有很高的观赏价值，其花的丰度和开花时间都是受植物激素调控的关键园艺性状。所有单花兜兰在顶端苞片中都有额外的侧芽，无法发育。在这项研究中，外源 GA3 应用通过诱导其早期抽薹而不是优势花的花转变来促进胼胝体的开花。施用GA3有效促进侧花分化，形成二花花序。GA 促进侧花形成涉及 GA 与吲哚-3-乙酸 (IAA) 和细胞分裂素 (CTKs) 相互作用，鉴于 CTK 含量降低和 CTK 合成基因的下调表达，IAA 含量增加和下调表达IAA 降解，和转运基因的上调表达。此外，GA通过第5阶段表达的PcDELLA、PcTCP15和PcXTH9促进抽薹，并通过PcAP3、PcPI和PcSEP的表达促进开花。本研究提供了对胼胝体花发育调控机制的深入了解。