• 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.

中文翻译：

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B 类和 C 类 MADS-box 基因的不对称表达模式对应于美人蕉不对称指定的雄性特征

• 美人蕉是一种常见的观赏植物，花朵不对称，有彩色花瓣状退化雄蕊。唯一能育的雄蕊包括单鞘花药和花瓣状附属物，代表姜目中最低的雄蕊数。不对称雄蕊花瓣状的分子机制仍然知之甚少。在这里，我们研究了美人蕉雄蕊的身份规范。
• 我们在雄蕊花的身份转换方面观察了四种异常花，并分析了相应的花对称性变化。我们使用原位杂交在正常美人蕉雄蕊中进一步测试了 B 类和 C 类 MADS-box 基因的表达模式。
• 雄蕊中的同种异型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高于其他雄蕊部分。这种不对称的表达模式恰好对应于美人蕉的不对称特性。
• 我们将C. indica确定为在 Zingiberales 中综合研究雄蕊器官特性和花对称性的模型物种。我们假设同源基因以推定的剂量依赖性方式指定花器官身份。结果增加了目前对器官特性相关的花卉对称性的理解。