Key Laboratory of Plant Resources Conservation and Sustainable Utilization, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, Guangdong, China.
National Key Laboratory of Plant Molecular Genetics, CAS Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai, China.
Plant Biol (Stuttg). 2021 Jul;23(4):540-545. doi: 10.1111/plb.13231. Epub 2021 May 10.
Canna indica is a common ornamental plant with asymmetric flowers having colourful petaloid staminodes. The only fertile stamen comprises a one-theca anther and a petaloid appendage and represents the lowest stamen number in the order Zingiberales. The molecular mechanism for the asymmetric androecial petaloidy remains poorly understood. Here, we studied the identity specification in Canna stamen. We observed four types of abnormal flower in terms of androecium identity transformation and analysed the corresponding floral symmetry changes. We further tested the expression patterns of B- and C-class MADS-box genes using in situ hybridization in normal Canna stamen. Homeotic conversions in the androecium were accompanied by floral symmetry changes, and the asymmetric stamen is key in contributing to the floral asymmetry. Both B- and C-class genes exhibited higher expression levels in the anther primordium than in other androecial parts. This asymmetric expression pattern precisely corresponded to the asymmetric identities of the Canna androecium. We identified C. indica as a model species for studying androecial organ identity and floral symmetry synthetically in Zingiberales. We hypothesized that homeotic genes specify floral organ identity in a putative dose-dependent manner. The results add to the current understanding of organ identity-related floral symmetry.
姜目植物的最低雄蕊类型为一花药一室的雄蕊和瓣状附属物，具有不对称花朵的姜目植物通常作为观赏植物。姜目植物的雄性器官瓣状化的分子机制尚不清楚。本文研究了美人蕉雄蕊的身份特化。我们观察到 4 种雄蕊身份转化的异常花，并分析了相应的花对称性变化。进一步通过原位杂交检测了 B 类和 C 类 MADS-box 基因在正常美人蕉雄蕊中的表达模式。雄蕊的同态转换伴随着花对称性的变化，不对称的雄蕊是导致花不对称的关键。B 类和 C 类基因在花药原基中的表达水平均高于其他雄蕊部分。这种不对称的表达模式与美人蕉雄蕊的不对称身份精确对应。本文将美人蕉鉴定为一个综合研究姜目雄蕊器官身份和花对称性的模式物种。我们假设同源异型基因以假定的剂量依赖方式特化花器官身份。该研究结果增加了对与器官身份相关的花对称性的理解。
