Arabidopsis Bax inhibitor-1 functions as an attenuator of biotic and abiotic types of cell death.
Programmed cell death (PCD) is a common process in eukaryotes during development and in response to pathogens and stress signals. Bax inihibitor-1 (BI-1) is proposed to be a cell death suppressor that is conserved in both animals and plants, but the physiological importance of BI-1 and the impact of its loss of function in plants are still unclear. In this study, we identified and characterized two independent Arabidopsis mutants with a T-DNA insertion in the AtBI1 gene. The phenotype of atbi1-1 and atbi1-2, with a C-terminal missense mutation and a gene knockout, respectively, was indistinguishable from wild-type plants under normal growth conditions. However, these two mutants exhibit accelerated progression of cell death upon infiltration of leaf tissues with a PCD-inducing fungal toxin fumonisin B1 (FB1) and increased sensitivity to heat shock-induced cell death. Under these conditions, expression of AtBI1 mRNA was up-regulated in wild-type leaves prior to the activation of cell death, suggesting that increase of AtBI1 expression is important for basal suppression of cell death progression. Over-expression of AtBI1 transgene in the two homozygous mutant backgrounds rescued the accelerated cell death phenotypes. Together, our results provide direct genetic evidence for a role of BI-1 as an attenuator for cell death progression triggered by both biotic and abiotic types of cell death signals in Arabidopsis.
Watanabe
Naohide
N
Biotechnology Center for Agriculture and the Environment, Rutgers, The State University of New Jersey, New Brunswick, NJ 08901-8520, USA.
Lam
Eric
E
D000595:Amino Acid Sequence; D017209:Apoptosis; D017360:Arabidopsis / Q000033:anatomy & histology / Q000235:genetics / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000502:physiology*; D001483:Base Sequence; D004269:DNA, Bacterial / Q000235:genetics; D037341:Fumonisins / Q000494:pharmacology; D006358:Hot Temperature; D008565:Membrane Proteins / Q000235:genetics / Q000502:physiology*; D008969:Molecular Sequence Data; D016254:Mutagenesis, Insertional; D009154:Mutation; D010641:Phenotype; D018515:Plant Leaves / Q000033:anatomy & histology / Q000187:drug effects / Q000378:metabolism; D015398:Signal Transduction / Q000235:genetics; D019076:Transgenes; D015854:Up-Regulation
C491862:ATBI-1 protein, Arabidopsis; D029681:Arabidopsis Proteins; D004269:DNA, Bacterial; D037341:Fumonisins; D008565:Membrane Proteins; C036483:T-DNA; C056933:fumonisin B1