Evolution and genetic control of the floral ground plan

First author: David R. Smyth; Affiliations: Monash University (莫纳什大学): Melbourne, Australia

Corresponding author: David R. Smyth

The floral ground plan is a map of where and when floral organ primordia (原基) arise. New results combining the defined phylogeny of flowering plants with extensive character mapping have predicted that the angiosperm ancestor had whorls (轮生) rather than spirals (螺旋) of floral organs in large numbers, and was bisexual (两性的). More confidently, the monocot ancestor likely had three organs in each whorl, whereas the rosid (蔷薇类) and asterid (菊类) ancestor (Pentapetalae) had five, with the perianth (花被) now divided into sepals (萼片) and petals (花瓣). Genetic mechanisms underlying the establishment of the floral ground plan are being deduced using model species, the rosid Arabidopsis, the asteroid Antirrhinum(金鱼草), and in grasses such as rice. In this review, evolutionary and genetic conclusions are drawn together, especially considering how known genes may control individual processes in the development and evolution of ground plans. These components include organ phyllotaxis, boundary formation, organ identity, merism (the number or organs per whorl), variation in the form of primordia, organ fusion, intercalary growth (居间生长), floral symmetry, determinacy and, finally, cases where the distinction between flowers and inflorescences is blurred. It seems likely that new pathways of ground plan evolution, and new signalling mechanisms, will soon be uncovered by integrating morphological and genetic approaches.

花器官平面图显示了花器官原基何时、何地出现。结合开花植物的系统进化树与新的特征图谱分析已经预测被子植物祖先的花器官更有可能是轮生的，而不是螺旋的，并且是两性花。另外，单子叶祖先在每一轮的花器官都是三个，而蔷薇类和菊类植物有五个花器官，并且双子叶的花被分化形成了萼片和花瓣。现有的研究通过一些模式植物，如双子叶蔷薇类植物拟南芥、菊类植物金鱼草以及草本植物水稻等详细研究了植物花器官平面图潜在的遗传调控机制。本综述从演化和遗传两个方向总结了有关花器官平面图的研究进展，尤其是调控花器官发育和演化单个进程的调控基因。这些进程包括器官排序、边界形成、器官属性、每轮的器官数、原基形式的变异、器官融合、居间生长、花对称、花决定以及最后的花与花序区分模糊。作者认为通过形态学以及遗传学方法的整合，很快便能够解析植物平面图演化相关的新通路和信号机制。

通讯：David R. Smyth (https://www.monash.edu/science/schools/biological-sciences/staff2/smyth)

研究方向：花形态的基因调控；花瓣起始与花瓣丢失；以拟南芥为模式植物研究调控基因。

doi: https://doi.org/10.1111/nph.15282

Journal: New Phytologist

First Published: 30 June, 2018

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