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

Abstract

SummaryD-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 pattern compared to P5CS1-GFP in root tips, leaves and flower organs. These data demonstrate that the Arabidopsis P5CS enzymes perform non-redundant functions, and that P5CS1 is insufficient for compensation of developmental defects caused by inactivation of P5CS2.

Intron-mediated alternative splicing of Arabidopsis P5CS1 and its association with natural variation in proline and climate adaptation

“…This finding was consistent with the P5CS1 transcript in those F 1 seedlings being an approximately equal mixture of the Sha allele and truncated P5CS1 transcript containing exon 3 produced by the endogenous Col-0 P5CS1 [the T-DNA insertion in p5cs1-4 is in exon 14 (5)]. A higher exon 3-skip percentage was seen in Sha × p5cs1-1, in which expression of Col-0 P5CS1 was reduced because of a promoter T-DNA insertion (5). These data were consistent with variation within P5CS1, rather than Sha alleles of other genes that would be heterozygous in the F 1 seedlings, as the basis of increased exon 3-skip P5CS1production.…”

“…However, the overall importance of proline in drought adaptation is not as firmly established. In Arabidopsis thaliana, transcriptional up-regulation of Δ 1 -pyrroline-5-carboxylate synthetase1 (P5CS1) is essential for low ψ w -induced proline accumulation, and proline accumulation of p5cs1 mutants is only 15-20% of the wild-type level (4)(5)(6). Additional regulation of proline metabolism is likely but not understood.…”

The Arabidopsis ZINC FINGER PROTEIN3 Interferes with Abscisic Acid and Light Signaling in Seed Germination and Plant Development

“…GFP localization was performed on roots of p7FWG2-ZFP3-expressing seedlings using an Olympus confocal laser scanning microscope as described (Székely et al, 2008). Histochemical detection of pZFP3-GUS activity was performed as reported (Jefferson et al, 1987).…”

Kloning parsial gen penyandi P5CS dari tebu (Saccharum officinarum L.) Cloning of P5CS-encoding gene fragment from sugarcane (Saccharum officinarum L.)

“…Menurut Hur et al (2004) tanaman padi mempunyai dua gen yang menyandi P5CS yaitu OsP5CS1 dan OsP5CS2. Data terkini melaporkan bahwa kedua gen family P5CS tersebut (P5CS1 dan P5CS2) pada Arabidopsis thaliana menunjukkan peranan yang berbeda di dalam mengakumulasi prolin pada kondisi cekaman kekeringan (Szekely et al, 2008).…”