|Goaes Da Silva, Fracncisco|
Submitted to: Theoretical and Applied Genetics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/18/2003
Publication Date: 8/2/2003
Citation: WANG, G., WU, C., ZENG, L., HE, C., BARAOIDAN, M., GOAES DA SILVA, F., WILLIAMS, C.E., RONALD, P., LEUNG, H. 2004. ISOLATION AND CHARACTERIZATION OF RICE MUTANTS SUSCEPTIBLE TO XANTHOMONAS ORYZAE PV ORYZAE. THEORETICAL AND APPLIED GENETICS. 108:379-384. Interpretive Summary: Little is known about mechanisms that are involved in defending plants against attack from microbial pathogens. Rice plants containing the bacterial resistance-gene, Xa21, were subjected to mutagenesis in order to identify plants that were less resistant due to changes in genes other than Xa21. Fifteen such plants were identified. The mutated genes are expected to be involved in biochemical pathways necessary for resistance. Scientists working on plant resistance to microbes, insects and nematodes will benefit from the information presented. This work is the first step in identifying genes and biochemical pathways that work together to protect plants from pathogens. Once the genes are fully characterized the information can be used to modify plants, by either breeding or molecular methods, for more durable resistance.
Technical Abstract: The rice gene Xa21 confers resistance to diverse races of Xanthomonas oryzae pv oryzae (Xoo) and encodes a receptor-like kinase with leucine-rich repeats (LRRs) in the extracellular domain. To identify genes essential for the function of the Xa21 gene, 4,500 mutants induced by diepoxybutane (DEB) and fast neutrons (FN) were screened against to Philippine Xoo race 6 (PR6) for a change from resistance to susceptibility. From two greenhouse screens, 23 mutants were identified that had changed from resistant to fully susceptible (6) or partially susceptible (17) to PR6. All fully susceptible mutants carried rearrangements at the Xa21 locus as detected by PCR and Southern hybridization. The partially susceptible mutants had no detectable changes at the Xa21 locus based on Southern and PCR analyses. However two mutants were confirmed to have point mutations at the Xa21 locus. Different levels of susceptibility of some identified partially susceptible mutants were observed, suggesting that they may carry different mutations required for the Xa21-mediated resistance. The mutants identified in this study provide important materials for dissecting the Xa21 mediated resistance pathway in rice.