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Article|22 Apr 2022|OPEN
Exogenous GA3 promotes flowering in Paphiopedilum callosum (Orchidaceae) through bolting and lateral flower development regulation
Yuying Yin1,2 , Ji Li1,2 , Beiyi Guo1,2 , Lin Li1 , Guohua Ma1 , Kunlin Wu1 and Fengxi Yang4 , Genfa Zhu4 , Lin Fang1 , , Songjun Zeng,1,3 ,
1Guangdong Provincial Key Laboratory of Applied Botany, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou 510650, China
2University of the Chinese Academy of Sciences, Beijing 100049, China
3Key Laboratory of South China Agricultural Plant Molecular Analysis and Gene Improvement, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou 510650, China
4Guangdong Key Laboratory of Ornamental Plant Germplasm Innovation and Utilization, Environmental Horticulture Research Institute, Guangdong Academy of Agricultural Sciences, Guangzhou 510640, China
*Corresponding author. E-mail: linfang@scbg.ac.cn,zengsongjun@scib.ac.cn

Horticulture Research 9,
Article number: uhac091 (2022)
doi: https://doi.org/10.1093/hr/uhac091
Views: 176

Received: 22 Dec 2021
Accepted: 05 Apr 2022
Published online: 22 Apr 2022

Abstract

Paphiopedilum orchids have a high ornamental value, and their 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 gibberellin (GA3) application promoted flowering of Pathiopedilum 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 lateral flower formation involved GA interacting with indole-3-acetic acid (IAA) and cytokinins (CTKs), given the decreased CTK content and downregulated expression of CTK synthesis genes, the increased IAA content and downregulated expression of IAA degradation, and the upregulated expression of transport genes. Further, GA acted via PcDELLAPcTCP15, and PcXTH9 expressed in stage 5 to promote bolting, and via expression of PcAP3PcPI, and PcSEP to promote flowering. This study provides insight into mechanisms regulating flower development of P. callosum.