Carey Shane, Zenchyzen Brandi, Deneka A J, Hall Jocelyn C
Department of Biological Sciences, University of Alberta, Edmonton, AB, Canada.
Front Plant Sci. 2023 Feb 9;13:1085900. doi: 10.3389/fpls.2022.1085900. eCollection 2022.
Nectaries are a promising frontier for plant evo-devo research, and are particularly fascinating given their diversity in form, position, and secretion methods across angiosperms. Emerging model systems permit investigations of the molecular basis for nectary development and nectar secretion across a range of taxa, which addresses fundamental questions about underlying parallelisms and convergence. Herein, we explore nectary development and nectar secretion in the emerging model taxa, (Cleomaceae), which exhibits a prominent adaxial nectary. First, we characterized nectary anatomy and quantified nectar secretion to establish a foundation for quantitative and functional gene experiments. Next, we leveraged RNA-seq to establish gene expression profiles of nectaries across three key stages of development: pre-anthesis, anthesis, and post-fertilization. We then performed functional studies on five genes that were putatively involved in nectary and nectar formation: (, (, and a highly expressed but uncharacterized transcript. These experiments revealed a high degree of functional convergence to homologues from other core Eudicots, especially . , redundantly with and , are required for nectary initiation. Concordantly, is essential for nectar formation and secretion, which indicates that the process is eccrine based in . While demonstration of conservation is informative to our understanding of nectary evolution, questions remain. For example, it is unknown which genes are downstream of the developmental initiators , , and , or what role the gene family plays in nectary initiation in this family. Further to this, we have initiated a characterization of associations between nectaries, yeast, and bacteria, but more research is required beyond establishing their presence. is an excellent model for continued research into nectary development because of its conspicuous nectaries, short generation time, and close taxonomic distance to .
蜜腺是植物进化发育生物学研究中一个很有前景的前沿领域，鉴于其在被子植物中的形态、位置和分泌方式的多样性，尤其引人入胜。新兴的模式系统使得我们能够对一系列分类群中蜜腺发育和花蜜分泌的分子基础进行研究，这有助于解决有关潜在平行性和趋同性的基本问题。在此，我们探索了新兴模式分类群（白花菜科）中蜜腺的发育和花蜜分泌，该分类群具有显著的近轴蜜腺。首先，我们对蜜腺的解剖结构进行了表征，并对花蜜分泌进行了量化，为定量和功能基因实验奠定了基础。接下来，我们利用RNA测序技术建立了蜜腺在三个关键发育阶段（花前、花期和受精后）的基因表达谱。然后，我们对五个假定参与蜜腺和花蜜形成的基因进行了功能研究：（，（，以及一个高表达但未表征的转录本。这些实验揭示了与其他核心真双子叶植物的同源基因在功能上具有高度的趋同性，尤其是。，与和冗余，是蜜腺起始所必需的。同样，对于花蜜的形成和分泌至关重要，这表明在该过程中是基于外分泌的。虽然保守性的证明有助于我们理解蜜腺的进化，但问题仍然存在。例如，尚不清楚哪些基因位于发育起始因子、和的下游，或者基因家族在该科蜜腺起始中起什么作用。除此之外，我们已经开始对蜜腺、酵母和细菌之间的关联进行表征，但除了确定它们的存在之外，还需要更多的研究。由于其明显的蜜腺、较短的世代时间以及与的近缘分类距离，是继续研究蜜腺发育的优秀模式。
