Floral traits often show correlated variation within and among species. For species with fused petals, strong correlations among corolla tube, stamen, and pistil length are particularly prevalent, and these three traits are considered an intra-floral functional module. Pleiotropy has long been implicated in such modular integration of floral traits, but empirical evidence based on actual gene function is scarce. We tested the role of pleiotropy in the expression of intra-floral modularity in the monkeyflower species Mimulus verbenaceus by transgenic manipulation of a homolog of Arabidopsis PRE1. Downregulation of MvPRE1 by RNA interference resulted in simultaneous decreases in the lengths of corolla tube, petal lobe, stamen, and pistil, but little change in calyx and leaf lengths or organ width. Overexpression of MvPRE1 caused increased corolla tube and stamen lengths, with little effect on other floral traits. Our results suggest that genes like MvPRE1 can indeed regulate multiple floral traits in a functional module but meanwhile have little effect on other modules, and that pleiotropic effects of these genes may have played an important role in the evolution of floral integration and intra-floral modularity.

中文翻译：

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马鞭草 PRE1 同源物对花性状的模块化调控：多效性在花整合中的作用的意义

花性状通常表现出物种内部和物种之间的相关变异。对于融合花瓣的物种，花冠管、雄蕊和雌蕊长度之间的强相关性尤为普遍，这三个特征被认为是花内功能模块。多效性长期以来一直与花性状的这种模块化整合有关，但基于实际基因功能的经验证据很少。我们通过转基因操作拟南芥 PRE1 的同源物，测试了多效性在猴花种马鞭草属植物花内模块性表达中的作用。RNA干扰对MvPRE1的下调导致花冠管、花瓣叶、雄蕊和雌蕊的长度同时减少，但花萼和叶片长度或器官宽度几乎没有变化。MvPRE1 的过表达导致花冠筒和雄蕊长度增加，对其他花性状影响不大。我们的研究结果表明，像MvPRE1这样的基因确实可以调节一个功能模块中的多个花性状，但同时对其他模块几乎没有影响，这些基因的多效性可能在花整合和花内模块性的进化中发挥了重要作用.