摘要
As calcium sensors, plant calcium-dependent protein kinases(CDPKs) play important roles in plants' responses to various abiotic stresses. Here, we report the functional characterization of CPK28, a member of the CDPK family in Arabidopsis, in response to osmotic stress.The cpk28 mutant, a loss-of-function mutant, exhibited an NaCl- and mannitol-sensitive phenotype in green cotyledons, while CPK28-overexpressing plants displayed stronger tolerance to NaCl and mannitol stresses than wildtype plants. Reverse transcriptase-polymerase chain reaction and beta-glucuronidase staining assays showed that NaCl and mannitol stresses induced CPK28. CPK28-overexpressing lines accumulated significantly more proline relative to wild-type plants and mutant plants under NaCl and mannitol stresses. Transient expression of CPK28-GFP in mesophyll cell protoplasts, as well as stable transgenic lines expressing CPK28-GFP, showed that CPK28 was localized in the plasma membrane. Expression levels of known stress-responsive genes were not significantly altered in the null mutant and overexpression lines,suggesting that CPK28 possibly mediated the stress response via the regulation of target proteins rather than via regulation at the level of transcription. Meanwhile, CPK28could autophosphorylate. Taken together, these data demonstrated that CPK28, a potential positive regulator, is involved in the response to osmotic stress in Arabidopsis.
As calcium sensors, plant calcium-dependent protein kinases （CDPKs） play important roles in plants＇ responses to various abiotic stresses. Here, we report the functional characterization of CPK28, a member of the CDPK family in Arabidopsis, in response to osmotic stress. The cpk28 mutant, a loss-of-function mutant, exhibited an NaC1- and mannitol-sensitive phenotype in green cotyle- dons, while CPK28-overexpressing plants displayed stronger tolerance to NaC1 and mannitol stresses than wild- type plants. Reverse transcriptase-polymerase chain reac- tion and beta-glucuronidase staining assays showed that NaC1 and mannitol stresses induced CPK28. CPK28- overexpressing lines accumulated significantly more pro- line relative to wild-type plants and mutant plants under NaC1 and mannitol stresses. Transient expression of CPK28-GFP in mesophyll cell protoplasts, as well as sta- ble transgenic lines expressing CPK28-GFP, showed that CPK28 was localized in the plasma membrane. Expression levels of known stress-responsive genes were not signifi- cantly altered in the null mutant and overexpression lines, suggesting that CPK28 possibly mediated the stress response via the regulation of target proteins rather than via regulation at the level of transcription. Meanwhile, CPK28 could autophosphorylate. Taken together, these data dem- onstrated that CPK28, a potential positive regulator, is involved in the response to osmotic stress in Arabidopsis.
基金
supported by the National Genetically Modified Organisms Breeding Major Projects(2011ZX08009-002)
