Duplicated P5CS genes of Arabidopsis play distinct roles in stress regulation and developmental control of proline biosynthesis

作者：Gyöngyi Székely, Edit Ábrahám, Ágnes Cséplö, Gábor Rigó, Laura Zsigmond, Jolán Csiszár, Ferhan Ayaydin, N. Strizhov, Ján Jásik, Elmon Schmelzer, Csaba Koncz, László Szabados · 发表于：The Plant Journal · 年份：2007 · DOI：10.1111/j.1365-313x.2007.03318.x · 被引用次数：725 · 研究领域：Plant Stress Responses and Tolerance、Plant Molecular Biology Research、Plant Gene Expression Analysis

Delta-1-pyrroline-5-carboxylate synthetase enzymes, which catalyse the rate-limiting step of proline biosynthesis, are encoded by two closely related P5CS genes in Arabidopsis. Transcription of the P5CS genes is differentially regulated by drought, salinity and abscisic acid, suggesting that these genes play specific roles in the control of proline biosynthesis. Here we describe the genetic characterization of p5cs insertion mutants, which indicates that P5CS1 is required for proline accumulation under osmotic stress. Knockout mutations of P5CS1 result in the reduction of stress-induced proline synthesis, hypersensitivity to salt stress, and accumulation of reactive oxygen species. By contrast, p5cs2 mutations cause embryo abortion during late stages of seed development. The desiccation sensitivity of p5cs2 embryos does not reflect differential control of transcription, as both P5CS mRNAs are detectable throughout embryonic development. Cellular localization studies with P5CS-GFP gene fusions indicate that P5CS1 is sequestered into subcellular bodies in embryonic cells, where P5CS2 is dominantly cytoplasmic. Although proline feeding rescues the viability of mutant embryos, p5cs2 seedlings undergo aberrant development and fail to produce fertile plants even when grown on proline. In seedlings, specific expression of P5CS2-GFP is seen in leaf primordia where P5CS1-GFP levels are very low, and P5CS2-GFP also shows a distinct cell-type-specific and subcellular localization patter...