EFR is a plasma-membrane resident receptor responsible for recognition of microbial elongation factorTu （EF-Tu） and thus triggering plant innate immunity to fend off phytopathogens. Functional EFR must be subject to...EFR is a plasma-membrane resident receptor responsible for recognition of microbial elongation factorTu （EF-Tu） and thus triggering plant innate immunity to fend off phytopathogens. Functional EFR must be subject to the endoplasmic reticulum quality control （ERQC） machinery for the correct folding and proper assembly in order to reach its final destination. Genetic studies have demonstrated that ERD2b, a counterpart of the yeast or mammalian HDEL receptor ERD2 for retaining proteins in the endoplasmic reticulum （ER） lumen, is required for EFR function in plants （Li et al., 2009）. In this study, we characterized the Arabidopsis glucosidase Ⅱ β--subunit via the H DEL motif against the non-redundant protein database. Data mining also revealed that the glucosidase Ⅱ β--subunit gene has a highly similar expression pattern to ERD2b and the other known ERQC components involved in EFR biogenesis. Importantly, the T-DNA insertion lines of the glucosidase Ⅱ β-subunit gene showed that EFR-controlled responses were substantially reduced or completely blocked in these mutants. The responses include seedling growth inhibition, induction of marker genes, MAP kinase activation, and callose deposition, trigged by peptide elf18, a full mimic of E F-Tu. Taken together, ourdata indicate a requirement of the glucosidase Ⅱ β-subunitfor EFR function.展开更多
Programmed cell death （PCD） is a central regulatory process in both plant development and in plant responses to pathogens. PCD requires a coordinate activation of pro-apoptotic factors such as proteases and suppress...Programmed cell death （PCD） is a central regulatory process in both plant development and in plant responses to pathogens. PCD requires a coordinate activation of pro-apoptotic factors such as proteases and suppressors inhibiting and modulating these processes. In plants, various caspase-like cysteine proteases as well as serine proteases have been implicated in PCD. Here, we show that a serine protease （Kunitz trypsin） inhibitor （KTI1） of Arabidopsis acts as a functional KTI when produced in bacteria and in planta. Expression of AtKTI1 is induced late in response to bacterial and fungal elicitors and to salicylic acid. RNAi silencing of the AtKTI1 gene results in enhanced lesion development after infiltration of leaf tissue with the PCD-eliciting fungal toxin fumonisin B1 （FB1） or the avirulent bacterial pathogen Pseudomonas syringae pv tomato DC3000 carrying avrB （Pst avrB）. Overexpression of AtKTI1 results in reduced lesion development after Pst avrB and FB1 infiltration. Interestingly, RNAi silencing of AtKTI1 leads to enhanced resistance to the virulent pathogen Erwinia carotovora subsp, carotovora SCC1, while overexpression of AtKTI1 leads to higher susceptibility towards this pathogen. Together, these data indicate that AtKTI1 is involved in modulating PCD in plant-pathogen interactions.展开更多
文摘EFR is a plasma-membrane resident receptor responsible for recognition of microbial elongation factorTu （EF-Tu） and thus triggering plant innate immunity to fend off phytopathogens. Functional EFR must be subject to the endoplasmic reticulum quality control （ERQC） machinery for the correct folding and proper assembly in order to reach its final destination. Genetic studies have demonstrated that ERD2b, a counterpart of the yeast or mammalian HDEL receptor ERD2 for retaining proteins in the endoplasmic reticulum （ER） lumen, is required for EFR function in plants （Li et al., 2009）. In this study, we characterized the Arabidopsis glucosidase Ⅱ β--subunit via the H DEL motif against the non-redundant protein database. Data mining also revealed that the glucosidase Ⅱ β--subunit gene has a highly similar expression pattern to ERD2b and the other known ERQC components involved in EFR biogenesis. Importantly, the T-DNA insertion lines of the glucosidase Ⅱ β-subunit gene showed that EFR-controlled responses were substantially reduced or completely blocked in these mutants. The responses include seedling growth inhibition, induction of marker genes, MAP kinase activation, and callose deposition, trigged by peptide elf18, a full mimic of E F-Tu. Taken together, ourdata indicate a requirement of the glucosidase Ⅱ β-subunitfor EFR function.
文摘Programmed cell death （PCD） is a central regulatory process in both plant development and in plant responses to pathogens. PCD requires a coordinate activation of pro-apoptotic factors such as proteases and suppressors inhibiting and modulating these processes. In plants, various caspase-like cysteine proteases as well as serine proteases have been implicated in PCD. Here, we show that a serine protease （Kunitz trypsin） inhibitor （KTI1） of Arabidopsis acts as a functional KTI when produced in bacteria and in planta. Expression of AtKTI1 is induced late in response to bacterial and fungal elicitors and to salicylic acid. RNAi silencing of the AtKTI1 gene results in enhanced lesion development after infiltration of leaf tissue with the PCD-eliciting fungal toxin fumonisin B1 （FB1） or the avirulent bacterial pathogen Pseudomonas syringae pv tomato DC3000 carrying avrB （Pst avrB）. Overexpression of AtKTI1 results in reduced lesion development after Pst avrB and FB1 infiltration. Interestingly, RNAi silencing of AtKTI1 leads to enhanced resistance to the virulent pathogen Erwinia carotovora subsp, carotovora SCC1, while overexpression of AtKTI1 leads to higher susceptibility towards this pathogen. Together, these data indicate that AtKTI1 is involved in modulating PCD in plant-pathogen interactions.
