Rivarola-Sena Ana C, Vialette Aurélie C, Andres-Robin Amélie, Chambrier Pierre, Bideau Loïc, Franco-Zorrilla Jose M, Scutt Charles P
Laboratoire Reproduction et Développement des Plantes (CNRS UMR 5667), Ecole Normale Supérieure de Lyon, 69364 Lyon Cedex 7, France.
Centro Nacional de Biotecnología-Consejo Superior de Investigaciones Científicas, C/Darwin3, 28049 Madrid, Spain.
Ann Bot. 2024 Dec 31;134(6):1037-1054. doi: 10.1093/aob/mcae140.
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 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.
We investigate SPT's molecular and functional evolution using phylogenetic reconstruction, yeast two-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.
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 paralogue ALCATRAZ (ALC), which appear to have arisen through a large-scale duplication within Brassicales. We find that SPT orthologues 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 carpel margin meristem in Brassicaceae.
We conclude that changes in SPT's expression pattern made a major contribution to the evolution of its developmental role in the gynoecium of Brassicaceae. 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.
SPATULA（SPT）在拟南芥中编码一种碱性螺旋-环-螺旋转录因子，其在花柱、柱头和胎座框组织的发育中发挥作用，这些组织均起源于雌蕊的心皮边缘分生组织。在此，我们采用比较研究方法来探究SPT的进化历程，并确定可能对其在雌蕊发育中的作用有贡献的变化。
我们利用系统发育重建、蛋白质-蛋白质相互作用的酵母双杂交分析、基于微阵列的蛋白质-DNA相互作用分析、植物转化试验、RNA原位杂交以及启动子序列的计算机分析，来研究SPT的分子和功能进化。
我们证明SPT谱系起源于真叶植物基部，源自一类可能受光调控的转录因子，通过基因复制，随后失去了一个活性光敏色素结合（APB）结构域。我们还阐明了SPT及其旁系同源物ALCATRAZ（ALC）更近的进化历程，它们似乎是通过十字花科内的大规模复制产生的。我们发现，来自不同种子植物类群的SPT直系同源物在蛋白质-蛋白质和蛋白质-DNA相互作用方面具有惊人相似的能力，并且来自广泛分类范围植物的SPT编码区能够在转基因拟南芥中互补功能缺失的spt突变。然而，SPT的表达模式在被子植物中似乎已经发生了显著进化，并且我们确定了SPT启动子区域的结构变化，这些变化与十字花科中源自心皮边缘分生组织的组织中高表达水平的获得相关。
我们得出结论，SPT表达模式的变化对其在十字花科雌蕊发育作用的进化做出了重大贡献。相比之下，SPT的主要生化能力及其许多直接转录靶点，至少自现存被子植物基部以来似乎一直保守。
