Functional Characterization Of XBAT31Gene In Arabidopsis

The rice (Oryza sativa) XB3is a E3ubiquitin ligase that contains a RING finger domain and an ankyrin repeat domain. It can interact with the receptor-like kinase XA21which is a biotic stress response signal, and regulate the resistance to bacterial blight disease in rice.There are five homologous proteins of XB3in Arabidopsis, which also have RING finger domain and ankyrin repeat domain, named XBAT31(At2g28840), XBAT32(At5g57740), XBAT33(At5g07270), XBAT34(At4g14365), XBAT35(At3g23280) respectively. XB3is involved in the plant immune response, XBAT32and XBAT35are involved in the regulation of plant growth and development process, these researches shows that this kind of genes play significant roles in plant growth development and in the process of immune to pathogenic bacteria.Arabidopsis XBAT31has the highest homology with XB3, up to62.93%. So far, there are no researches on function identification of XBAT31, and XB3high participation disease resistance mechanism remains to be further research in rice. This research use RNAi technology for XBAT31gene in Arabidopsis and the role of immune response in their growth and development, function has carried on the preliminary appraisal, to fully disclose XBAT31gene function and mechanism lay the foundation. The main results were as follows:(1) XBAT31RNAi lines and wild type of XCC8004inoculation experiment results show that, the wild type and RNAi strain immune response was no significant difference of XCC8004, suggest XBAT31may not participate in Arabidopsis XCC8004immune process.(2) XBAT31RNAi lines and wild type physiological phenotypic analysis shows that under the condition of long day, relatively wild type, RNAi lines plant more short, the rosette leaves number were1-2pieces less, bolting time2-3days in advance and reduced numbers of silique, seed grain number remains unchanged, but each seed weight increased.(3) Ethylene "triple response" experiments show that the relative wild type, the RNAi XBAT31gene plants of strain at the top hook angle increases, hypocotyl length is shortened obviously, suggests XBAT31might be in arabidopsis plays a role of negative regulation of ethylene signaling pathway. Under the condition of adding ethylene receptor inhibitor of AgN03, RNAi lines seedling top hook angle and no obvious difference was found between wild type and hypocotyl length has no significant difference, showed the XBAT31to ethylene signaling pathways by AgNO3negative regulation function can be suppressed, that means XBAT31of ethylene signaling pathways control is located in the upstream of ethylene receptor.(4)XBAT31of RNAi lines increased seed weight, in the ethylene "triple response" experiments the seedling root length to no obvious difference compared with wild type, these profiles show that XBAT31besides participating in ethylene regulation pathway, also may participate in or influence the other signal transduction process in the process of plant growth and development.