Introduction Of A Nonhost Gene Rxo1 Into Rice Variety And Resistant Response To Rice Bacterial Leaf Streak Triggered By This Gene

Bacterial leaf streak (BLS) in rice is an important quarantine disease of plant in China. BLS causes subtantial economic losses in rice production, esepecial in hybrid rice. No resistance controlled by single R gene has been identified in rice. The resistance of rice to BLS is a quantitative trait. As the effect of the quantitative trait loci for resistance to BLS locatied in rice is small, it is limited to be used widely in the breeding for disease resistance.It has been hot issues that clone non-host resistance genes and the usage in improving the resistance of crops. The Rxol gene which identified and cloned from maize was a nonhost gene resistant to BLS of rice, which mediated hypersensitive reaction in transgenic rice lines infected by Xanthomonas oryzae pv. oryzicola (Xoc.). To overcome the safety concerns caused by selectable marker genes in transgenic plants, double right-border binary vector was used to cultivate marker-free breeding material. RT-PCR and real-time PCR were used to reveal the resistant mechanism of non-host resistance gene Rxol against Xoc. in rice.1. The non-host resistance gene Rxol was transferred into C418, an important restorer line of japonica hybrid rice in China, using double right-border T-DNA binary vector pMNDRBBin6-Rxco1 through Agrobacterium-mediated transformation.11 transgenic lines of C418 were Rxol-positive through PCR analysis.2. A homozygous T4 line containing a single copy of Rxol from transgenic 9804 plants were inoculated using a virulent Xoc strain. Hypersensitive reaction (HR) was triggered. The expression profiles of 6 genes related with HR and salicylic acid (SA) singal pathway were analyised by RT-PCR. The expression profiles were confirmed by real-time PCR. The results indicate that SA singal transduction pathway involved in the defence reaction induced by Rxol gene.3. Transcription factors play an important role in regulating plant defence reaction. WRKY genes expression upon the inoculation of Xoc were analyised by RT-PCR. The results showed that 11 genes were expressed differently in transgenic rice. Among 11 genes, 7 genes involved in and regulated resistance reactions in different ways. The results showed that SA and JA singaling pathway may be involved in the non-host resistance reaction induced by Rxol gene. The information of bioinformatics and phylogenetic analyse will be significant to investigate the resistance mechanism and the networks consisted of singal transduction pathways.