Laboratory of Bioinformatics, Department of Life Sciences, School of Agriculture, Meiji University, 1-1-1 Higashi-mita, Kawasaki 214-8571, Japan; Laboratory of Genetic Engineering, Graduate School of Life and Environmental Sciences, Kyoto Prefectural University, Shimogamo, Kyoto 606-8522, Japan.
Laboratory of Bioinformatics, Department of Life Sciences, School of Agriculture, Meiji University, 1-1-1 Higashi-mita, Kawasaki 214-8571, Japan.
Gene. 2020 Dec 15;762:145015. doi: 10.1016/j.gene.2020.145015. Epub 2020 Aug 9.
Phosphoenolpyruvate carboxylase (PEPC) is a carbon fixation enzyme which probably plays crucial roles in seed development. A greater number of PEPC isoforms are encoded in the soybean genome, while most of the PEPC isoforms are functionally unknown. In this study, we investigated on soybean PEPC expressed in the external layer of seed coat (ELSC) during seed formation. PEPC activity in ELSC ranged from 0.24 to 1.0 U/g F.W., which could be comparable to those in whole seeds at U per dry matter. Public RNA-Seq data in separated soybean seed tissues revealed that six plant-type PEPC isogenes were substantially expressed in ELSC, and Gmppc1 and Gmppc7 were highly expressed in hourglass cells of ELSC. Gene Ontology enrichment of co-expressed genes with Gmppc1 and Gmppc7 implicated a role of these isogenes in assisting energy production and cellulose biosynthesis. Comparison of PEPC sequences from 16 leguminous species hypothesized adaptive evolution of the Gmppc1 and Gmppc7 lineage after divergence from the other plant-type PEPC lineages. Molecular diversification of these plant-type PEPC was possibly accomplished by adaptation to the functions of the soybean seed tissues. This study indicates that energy demand in immature seeds may be a driving force for the molecular evolution of PEPC.
磷酸烯醇式丙酮酸羧化酶（PEPC）是一种碳固定酶，可能在种子发育中发挥关键作用。大豆基因组中编码了更多的 PEPC 同工型，而大多数 PEPC 同工型的功能尚不清楚。在这项研究中，我们研究了在种子形成过程中种皮外层（ELSC）中表达的大豆 PEPC。ELSC 中的 PEPC 活性范围为 0.24 至 1.0 U/g FW，与整个种子在 U 每干物质中的活性相当。分离的大豆种子组织中的公共 RNA-Seq 数据显示，六种植物型 PEPC 同系物在 ELSC 中大量表达，Gmppc1 和 Gmppc7 在 ELSC 的沙漏细胞中高度表达。与 Gmppc1 和 Gmppc7 共表达基因的基因本体富集表明这些同系物在协助能量产生和纤维素生物合成中发挥作用。来自 16 种豆科植物的 PEPC 序列比较假设，在与其他植物型 PEPC 谱系分化后，Gmppc1 和 Gmppc7 谱系发生了适应性进化。这些植物型 PEPC 的分子多样化可能是通过适应大豆种子组织的功能来实现的。本研究表明，不成熟种子的能量需求可能是 PEPC 分子进化的驱动力。
