Kostyun Jamie L, Preston Jill C, Moyle Leonie C
Department of Biology, Indiana University, Bloomington, IN 47405 USA.
Department of Plant Biology, The University of Vermont, Burlington, VT 05405 USA.
Evodevo. 2017 Oct 23;8:17. doi: 10.1186/s13227-017-0080-z. eCollection 2017.
Heterochronic shifts during mid- to late stages of organismal development have been proposed as key mechanisms generating phenotypic diversity. To determine whether late heterochronic shifts underlie derived floral morphologies within (Solanaceae)-a genus whose species have extensive and recently evolved floral diversity-we compared floral development of four diverse species (including an ambiguously ancestral or secondarily derived rotate, two putatively independently evolved campanulate, and a tubular morph) to the ancestral rotate floral form, as well as to an outgroup that shares this ancestral floral morphology.
We determined that early floral development (< 1 mm bud diameter, corresponding to completion of organ whorl initiation) is very similar among all species, but that different mature floral forms are distinguishable by mid-development (> 1 mm diameter) due to differential growth acceleration of corolla traits. Floral ontogeny among similar mature rotate forms remains comparable until late stages, while somewhat different patterns of organ growth are found between species with similar campanulate forms.
Our data suggest shared floral patterning during early-stage development, but that different heterochronic shifts during mid- and late-stage development contribute to divergent floral traits. Heterochrony thus appears to have been important in the rapid and repeated diversification of flowers.
在生物体发育的中后期发生的异时性转变被认为是产生表型多样性的关键机制。为了确定后期异时性转变是否是茄科中衍生花形态的基础——该属物种具有广泛且最近演化出的花多样性——我们将四个不同物种（包括一个不确定是祖先型还是次生衍生的辐射状、两个推测独立演化的钟状以及一个管状形态）的花发育与祖先辐射状花形态以及具有这种祖先花形态的外类群进行了比较。
我们确定，在所有物种中，早期花发育（花蕾直径<1毫米，对应器官轮起始完成）非常相似，但由于花冠特征的不同生长加速，不同的成熟花形态在发育中期（直径>1毫米）就可区分。相似成熟辐射状形态之间的花个体发育在后期之前仍具有可比性，而在相似钟状形态的物种之间发现了略有不同的器官生长模式。
我们的数据表明在早期发育过程中有共同的花模式形成，但中后期发育过程中不同的异时性转变导致了不同的花性状。因此，异时性似乎在茄属花的快速且反复多样化过程中起到了重要作用。
