Functional Analysis Of OsBIANK1 And Sulfite Oxidase Genes In Rice

Ankyrin repeat-containing proteins are abundant protein classes functioning in protein-protein interactions. Ankyrin repeat proteins (ANK) have been reported to be involved in various biological processes of plant growth and development, transport and defense responses. Previously, we identified a gene, OsBIANK1, encoding for an ANK protein, was up-regulated in defense response in rice after infection by Magnaporthe grisea or treatment with benzothiadiazole (BTH). To study the function of OsBIANK1 in disease resistance response, I constructed an overexpression vector 35S::OsBIANK1, and introduced into wild-type Arabidopsis plants using floral dip transformation protocol.35S::OsBIANK1 transgenic lines with single copy of the transgene were obtained. Homozygous lines were identified from the 3rd generation through screening and three homozygous lines for 35S::OsBIANK1 (OsBIANK1-OE#17,#24and #29) were chosen for further work. Disease phenotypes of the wild-type, OsBIANK1-OE plants were compared after inoculation with Pseudomonas syringae pv. tomato (Pst) DC3000 and Botrytis cinerea. As compared with the wild-type plants, the OsBIANK1-OE plants showed a significant reduced susceptibility to the pathogens. Furthermore, growth of Pst DC3000 in leaves of the OsBIANK1-OE plants was significantly reduced. After inoculation with Pst DC3000, the expression of PR-1 and PR-5 genes was up-regulated in the OsBIANK1-OE plants. And after inoculation with B. cinerea, expression of PDF1.2 and BIK1 genes was up-regulated in the OsBIANK1-OE plants. Additionally, after two days of treatment with some well-known defense-related chemical inducers such as salicylic acid (SA) and benzothaidiazole (BTH), the OsBIANK1-OE plants also showed a significant reduced susceptibility to Pst DC3000, growth of Pst DC3000 in leaves of the OsBIANK1-OE plants was also significantly reduced and less than that without treatment with SA and BTH. Moreover, after Botrytis infection, accumulation of reactive oxygen species (H2O2 and superoxide anion) in leaves of the OsBIANK1-OE plants was lower than those of the wild type plants. These results indicate that OsBIANK1 is a positive regulator of defense responses in Arabidopsis thaliana against both necrotrophic and biotrophic pathogens.Sulfite oxidase (SO) is one of molybdenum(Mo) enzymes in plant. SO has been reported to be involved in sulphur metabolism in plants, and can detoxifies excessive sulfite. Information on functions of SO in plant defense response against pathogen infection is lacking. In this study, I identified two SO genes from rice. To study the function of OsSO1 and OsSO2 in disease resistance response, I constructed overexpression vectors 35S::OsSO1 and 35S::OsSO2 and introduced them into wild-type plants using floral dip transformation protocol.35S::OsSO1 and 35S::OsSO2 transgenic lines with single copy of the transgene were obtained. Homozygous lines were identified from the 3rd generation through screening and three homozygous lines for 35S::OsSO1 (OsSO1-OE#19,#23) and 35S::OsSO2(OsSO2-OE#4) were chosen for further work. Disease phenotypes of the wild-type, OsSO1-OE and OsSO2-OE plants were compared after inoculation with Pst DC3000 and B. cinerea. As compared with the wild-type plants, the OsSO1-OE and OsSO2-OE plants showed a significant reduced susceptibility to the patogens. Furthermore, growth of Pst DC3000 in leaves of the OsSO1-OE and OsSO2-OE plants was significantly reduced. After inoculation with Pst DC3000, the expression of PR-1 and PR-5 genes was up-regulated in the OsSO1-OE and OsSO2-OE plants. And after inoculation with B. cinerea, expression of PDF1.2 and BIK1 genes was up-regulated in the OsSO1-OE and OsSO2-OE plants. Additionally, after two days of treatment with SA and BTH, the OsSO1-OE and OsSO2-OE plants showed a significant reduced susceptibility to Pst DC3000, growth of Pst DC3000 in leaves of the OsSO1-OE and OsSO2-OE plants was also significantly reduced and less than that without treatment with SA and BTH. Moreover, accumulation of reactive oxygen species in leaves of the OsSO1-OE and OsSO2-OE plants after Botrytis infection was less than that in the wild type plants. These results indicate that OsSO1 and OsSO2 are involved in defense response against pathogen infection.