Proline Accumulation Is Regulated by Transcription Factors Associated with Phosphate Starvation

作者：Dávid Aleksza, Gábor V. Horváth, Györgyi Sándor, László Szabados · 发表于：PLANT PHYSIOLOGY · 年份：2017 · DOI：10.1104/pp.17.00791 · 被引用次数：108 · 研究领域：Plant nutrient uptake and metabolism、Plant Micronutrient Interactions and Effects、Plant Stress Responses and Tolerance

Pro accumulation in plants is a well-documented physiological response to osmotic stress caused by drought or salinity. In Arabidopsis (Arabidopsis thaliana), the stress and ABA-induced Ɗ1-PYRROLINE-5-CARBOXYLATE SYNTHETASE1 (P5CS1) gene was previously shown to control Pro biosynthesis in such adverse conditions. To identify regulatory factors that control the transcription of P5CS1, Y1H screens were performed with a genomic fragment of P5CS1, containing 1.2-kB promoter and 0.8-kb transcribed regions. The myeloblastosis (MYB)-type transcription factors PHOSPHATE STARVATION RESPONSE1 (PHR1) and PHR1-LIKE1 (PHL1) were identified to bind to P5CS1 regulatory sequences in the first intron, which carries a conserved PHR1-binding site (P1BS) motif. Binding of PHR1 and PHL1 factors to P1BS was confirmed by Y1H, electrophoretic mobility assay and chromatin immunoprecipitation. Phosphate starvation led to gradual increase in Pro content in wild-type Arabidopsis plants as well as transcriptional activation of P5CS1 and PRO DEHYDROGENASE2 genes. Induction of P5CS1 transcription and Pro accumulation during phosphate deficiency was considerably reduced by phr1 and phl1 mutations and was impaired in the ABA-deficient aba2-3 and ABA-insensitive abi4-1 mutants. Growth and viability of phr1phl1 double mutant was significantly reduced in phosphate-depleted medium, while growth was only marginally affected in the aba2-3 mutants, suggesting that ABA is implicated in growth retardation in such nut...