研究芍药属新型退化雄蕊的发育和分子特征。
Developmental and molecular characterization of novel staminodes in Aquilegia.
机构信息
Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA, USA.
Ecology and Evolutionary Biology, Cornell University, Ithaca, NY, USA.
出版信息
Ann Bot. 2020 Jul 24;126(2):231-243. doi: 10.1093/aob/mcaa029.
BACKGROUND AND AIMS
The ranunculid model system Aquilegia is notable for the presence of a fifth type of floral organ, the staminode, which appears to be the result of sterilization and modification of the two innermost whorls of stamens. Previous studies have found that the genetic basis for the identity of this new organ is the result of sub- and neofunctionalization of floral organ identity gene paralogues; however, we do not know the extent of developmental and molecular divergence between stamens and staminodes.
METHODS
We used histological techniques to describe the development of the Aquilegia coerulea 'Origami' staminode relative to the stamen filament. These results have been compared with four other Aquilegia species and the closely related genera Urophysa and Semiaquilegia. As a complement, RNA sequencing has been conducted at two developmental stages to investigate the molecular divergence of the stamen filaments and staminodes in A. coerulea 'Origami'.
KEY RESULTS
Our developmental study has revealed novel features of staminode development, most notably a physical interaction along the lateral margin of adjacent organs that appears to mediate their adhesion. In addition, patterns of abaxial/adaxial differentiation are observed in staminodes but not stamen filaments, including asymmetric lignification of the adaxial epidermis in the staminodes. The comparative transcriptomics are consistent with the observed lignification of staminodes and indicate that stamen filaments are radialized due to overexpression of adaxial identity, while the staminodes are expanded due to the balanced presence of abaxial identity.
CONCLUSIONS
These findings suggest a model in which the novel staminode identity programme interacts with the abaxial/adaxial identity pathways to produce two whorls of laterally expanded organs that are highly differentiated along their abaxial/adaxial axis. While the ecological function of Aquilegia staminodes remains to be determined, these data are consistent with a role in protecting the early carpels from herbivory and/or pathogens.
背景与目的
毛茛科翠雀属植物系统因存在第五种花器官——退化雄蕊而引人注目，其似乎是由最内两轮雄蕊的败育和改造形成的。先前的研究发现，这种新器官的遗传基础是花器官身份基因的亚功能化和新功能化；然而，我们并不清楚雄蕊和退化雄蕊之间在发育和分子水平上的分歧程度。
方法
我们使用组织学技术描述了翠雀属‘折纸’退化雄蕊相对于雄蕊花丝的发育情况。这些结果与其他四个翠雀属物种以及亲缘关系较近的属乌头属和耧斗菜属进行了比较。作为补充，我们在两个发育阶段进行了 RNA 测序，以研究翠雀属‘折纸’中雄蕊花丝和退化雄蕊的分子分化。
主要结果
我们的发育研究揭示了退化雄蕊发育的新特征，最显著的是相邻器官沿侧向边缘的物理相互作用，这种相互作用似乎介导了它们的黏附。此外，在退化雄蕊中观察到背腹分化模式，但在雄蕊花丝中没有观察到，包括退化雄蕊的腹面表皮不对称木质化。比较转录组学与观察到的退化雄蕊木质化一致，并表明雄蕊花丝由于近轴身份的过表达而呈辐射状，而退化雄蕊由于背轴身份的平衡存在而扩展。
结论
这些发现表明，一种新的退化雄蕊身份程序与背腹身份途径相互作用，产生了两轮侧向扩展的器官，这些器官在背腹轴上高度分化。虽然翠雀属退化雄蕊的生态功能仍有待确定，但这些数据与它们在保护早期心皮免受食草动物和/或病原体侵害方面的作用是一致的。
Zotero 插件