目的:SPATULA(SPT)在拟南芥中编码一个基本的螺旋-环-螺旋转录因子,在风格的发育中起作用,柱头和复制组织,所有这些都来自雌蕊的心皮边缘分生组织(CMM)。这里,我们使用比较方法调查SPT的进化史,并确定可能导致其在绞股蓝发育中作用的变化.
方法:我们使用系统发育重建研究SPT的分子和功能进化,蛋白质-蛋白质相互作用的酵母-2-杂交分析,基于微阵列的蛋白质-DNA相互作用分析,植物转化试验,RNA原位杂交,和启动子序列的计算机分析。
结果:我们证明了SPT谱系通过基因复制,随后丢失了活性植物色素结合(APB)域,从潜在的光调节转录因子的进化枝产生于真叶树的基础。我们还阐明了SPT及其副词ALCATRAZ(ALC)的最新进化史,似乎是通过Brassicales内部的大规模复制而产生的。我们发现来自不同种子植物组的SPT直系同源物具有惊人的相似的蛋白质-蛋白质和蛋白质-DNA相互作用能力。并且来自广泛分类学植物的SPT编码区能够补充转基因拟南芥中的功能丧失spt突变。然而,SPT的表达模式似乎在被子植物中发生了显著的演变,并且我们确定了SPT启动子区域的结构变化,这些变化与油菜科中CMM引起的组织中高表达水平的获得相关。
结论:我们得出的结论是,SPT的表达模式的变化对其在油菜科的雌蕊中的发育作用的演变做出了重要贡献。相比之下,SPT的主要生化能力,以及它的许多直接转录靶标,至少从活的被子植物的基部开始,似乎就被保存了。
OBJECTIVE: SPATULA (SPT) encodes a basic Helix-Loop-Helix transcription factor in Arabidopsis thaliana that functions in the development of the style, stigma and replum tissues, all of which arise from the carpel margin meristem (CMM) of the gynoecium. Here, we use a comparative approach to investigate the evolutionary history of SPT and identify changes that potentially contributed to its role in gynoecium development.
METHODS: We investigate SPT\'s molecular and functional evolution using phylogenetic reconstruction, yeast-2-hybrid analyses of protein-protein interactions, microarray-based analyses of protein-DNA interactions, plant transformation assays, RNA in-situ hybridization, and in-silico analyses of promoter sequences.
RESULTS: We demonstrate the SPT lineage to have arisen at the base of euphyllophytes from a clade of potentially light-regulated transcription factors through gene duplication followed by the loss of an Active Phytochrome Binding (APB) domain. We also clarify the more recent evolutionary history of SPT and its paralog ALCATRAZ (ALC), which appear to have arisen through a large-scale duplication within Brassicales. We find that SPT orthologs from diverse groups of seed plants share strikingly similar capacities for protein-protein and protein-DNA interactions, and that SPT coding regions from a wide taxonomic range of plants are able to complement loss-of-function spt mutations in transgenic Arabidopsis. However, the expression pattern of SPT appears to have evolved significantly within angiosperms, and we identify structural changes in SPT\'s promoter region that correlate with the acquisition of high expression levels in tissues arising from the CMM in Brassicaeae.
CONCLUSIONS: We conclude that changes to SPT\'s expression pattern made a major contribution to the evolution of its developmental role in the gynoecium of Brassicaeae. By contrast, the main biochemical capacities of SPT, as well as many of its immediate transcriptional targets, appear to have been conserved at least since the base of living angiosperms.