Are petals sterile stamens or bracts? the origin and evolution of petals in the core eudicots
Are petals sterile stamens or bracts? the origin and evolution of petals in the core eudicots
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DOI：
10.1093/aob/mcm076
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发表时间：
2007-09-01
期刊：
影响因子：
4.2
通讯作者：
De Craene, Louis P. Ronse
中科院分区：
文献类型：
--
作者：
De Craene, Louis P. Ronse
背景本文的目的是讨论有争议的起源花瓣从花被片或雄蕊和花瓣的形态表达和花器官的身份基因在核心eudicots.Scope I挑战广泛持有的经典观点，即花瓣的形态来自雄蕊在核心eudicots. Scope I，和萼片从花被片或苞片。形态学数据表明，花被片衍生的花瓣已经独立地从Berberidopsis样原型的核心真双子叶植物的主要谱系中（即Escherds，Santalales和rosids）进化而来，并且退化雄蕊花瓣只出现在少数孤立的情况下，其中花瓣先前已经丢失（Carbellales，Rosales）。花瓣形态的连续变化之间的明确相关性，以及表明控制花器官发育的基因中发生了许多重复的情况，只能在系统发育的背景下才能完全理解。B-基因的表达起着根本性的作用，在花瓣的进化，通过控制花瓣性，但它不澄清花瓣homology.Conclusions增加synorganization的花在核心真双子叶植物与建立的花轮限制花瓣基因的表达，第二轮，减少花瓣与花被片的相似性，他们最初来自。一个增加的花的大小与次生一雄多雄蕊或polycarpelly可能会导致一个故障的限制基因的表达和逆转的祖先特征的花被发育。一个改变的“滑动边界”假说提出的核心真双子叶植物的花瓣性的花被和退化雄蕊花瓣的事件解释的转变。核心真双子叶植物的花被功能的重复变化与花瓣性向外花被轮的转移有关，或者与花瓣或萼片轮的损失有关，后者可以通过在花中包含苞片来补偿。花瓣的起源和进化似乎在分子基础上和从形态学的角度看一样复杂。
Background The aim of this paper is to discuss the controversial origins of petals from tepals or stamens and the links between the morphological expression of petals and floral organ identity genes in the core eudicots.Scope I challenge the widely held classical view that petals are morphologically derived from stamens in the core eudicots, and sepals from tepals or bracts. Morphological data suggest that tepal-derived petals have evolved independently in the major lineages of the core eudicots (i.e. asterids, Santalales and rosids) from Berberidopsis-like prototypes, and that staminodial petals have arisen only in few isolated cases where petals had been previously lost (Caryophyllales, Rosales). The clear correlation between continuous changes in petal morphology, and a scenario that indicates numerous duplications to have taken place in genes controlling floral organ development, can only be fully understood within a phylogenetic context. B-gene expression plays a fundamental role in the evolution of the petals by controlling petaloidy, but it does not clarify petal homology.Conclusions An increased synorganization of the flower in the core eudicots linked with the establishment of floral whorls restricts the petaloid gene expression to the second whorl, reducing the similarities of petals with tepals from which they were originally derived. An increased flower size linked with secondary polyandry or polycarpelly may lead to a breakdown of the restricted gene expression and a reversal to ancestral characteristics of perianth development. An altered 'sliding boundary' hypothesis is proposed for the core eudicots to explain shifts in petaloidy of the perianth and the event of staminodial petals. The repetitive changes of function in the perianth of the core eudicots are linked with shifts in petaloidy to the outer perianth whorl, or losses of petal or sepal whorls that can be secondarily compensated for by the inclusion of bracts in the flower. The origin and evolution of petals appears to be as complex on a molecular basis as it is from a morphological point of view.