Evolution of Vegetative Phase Change in the Acacieae

这个提议探讨了Acacieae（一个大型的，抗旱的，固氮的豆科植物部落）的营养阶段变化的进化。这一组包括只产生双羽状复叶的属，以及最近进化的一种属（金合欢），它最初产生复叶，但后来转而产生一种叫做叶状叶的单叶。栖息在金合欢中的是一组大约70种（Botrycephalae），它们只产生复叶。长期以来，人们一直认为这些物种代表了衍生的？叶状目物种的形态，但没有证据支持这一结论。营养发育的幼期是由高水平的mirna miR156和miR157决定的。本项目的工作假设是，通过miR156和/或miR157的长期高表达，芽孢头科从叶状门物种中产生。为了获得支持或反对这一假设的初步证据，我们将使用Northern分析方法，在几个叶状和双羽状金合欢物种中检测成熟miR156/miR157转录物的表达。编码miR156/miR157的基因将通过具有代表性的叶状和双羽类物种的下一代基因组DNA测序来鉴定。这将为qRT-PCR检测特定miR156/mIR157基因表达的可行性提供可能。这些实验的结果将提供“概念验证”。未来的研究旨在确定金合欢科幼虫和成虫性状表达变异的分子基础。更广泛的影响一年一度的费城科学嘉年华将在本富兰克林公园大道举办一个关于相变的展览。这个展览的目的是让参加这个嘉年华的孩子们知道植物是动态的，随着生长而变化。与会者将被要求找出常春藤和玉米幼叶和成年叶之间的所有差异，并将介绍金合欢和桉树的相变。用35S::miR156转化的拟南芥植物将被用来说明单个基因如何改变茎的整个结构。

This proposal explores the evolution of vegetative phase change in the Acacieae, a large, drought-resistant, tribe of nitrogen-fixing legumes. This group includes genera that produce only bipinnately compound leaves, and a more recently evolved genus (Acacia) that initially produces compound leaves, but then switches to the production of a simple leaf called a phyllode. Nested within Acacia is a group of approximately 70 species (Botrycephalae) that produce only compound leaves. It has long been assumed that these species represent derived ?juvenilized? forms of phyllodinous species, but there is no evidence for this conclusion. The juvenile phase of vegetative development is specified by high levels of the miRNAs, miR156 and miR157. The working hypothesis of this project is that the Botrycephalae arose from phyllodinous species by the prolonged, high expression of miR156 and/or miR157. To obtain preliminary evidence for or against this hypothesis, the expression of the mature miR156/miR157 transcripts will be examined in a few phyllodinous and bi-pinnate species of Acacia, using Northern analysis. The genes that encode miR156/miR157 will be identified by next-generation sequencing genomic DNA from a representative phyllodinous and bi-pinnate species. This will make it possible to test the feasibility of examining the expression of specific miR156/mIR157 genes by qRT-PCR. The results of these experiments will provide the ?proof-of-concept? for a future proposal aimed at determining the molecular basis for variation in the expression of juvenile and adult traits in the Acacieae. Broader ImpactAn exhibit on phase change will be created for annual Philadelphia Science Carnival, held on the Ben Franklin Parkway. The goal of this exhibit will be to teach the many children who attend this carnival that plants are dynamic, and change as they grow. Attendees will be asked to find all the differences between juvenile and adult ivy and corn leaves, and will be introduced to phase change in Acacia and Eucalyptus. Arabidopsis plants transformed with 35S::miR156 will be used to illustrate how a single gene can change the entire architecture of the shoot.