title: Identification and fine-mapping of a new resistance gene, Xa40, conferring resistance to bacterial blight races in rice (Oryza sativa L.).
abstract: A new bacterial blight resistance gene has been identified through fine-mapping, which confers high levels of resistance to all Korean Xanthomonas oryzae pv. oryzae (Xoo) races, including the new Xoo race K3a. Rice bacterial leaf blight (BB) disease caused by Xanthomonas oryzae pv. oryzae (Xoo) is a serious constraint to rice production in Asia and Africa. The japonica advanced backcross breeding lines derived from the indica line IR65482-7-216-1-2 in the background of cultivar Junam are resistant to all Korean BB races, including K3a. To identify the gene(s) involved in resistance to Korean Xoo races, the association of genotypic and phenotypic variations was examined in two F2 populations derived from the crosses between 11325 (IR83261-3-7-23-6-2-1-1-2-1-2)/Anmi and 11325/Ilpum. The segregation ratios of F2 individuals from the crosses of 11325/Anmi and 11325/Ilpum were 578 resistant:209 susceptible and 555 resistant:241 susceptible, respectively, which is consistent with the expected allelic frequency of a 3:1 ratio. Genetic analysis using graphical mapping indicated that resistance (R) was controlled by a new resistance gene linked with the flanking markers RM27320 and ID55.WA18-5 within an approximately 80-kb region between 28.14 and 28.22 Mbp on chromosome 11. The eight candidate genes functionally predicted were included in the target region. Examination of the candidate genes by RT-PCR analysis only corroborated with the significant difference in transcript levels of the WAK3 gene in the presence or absence of pathogen infection. Allelism tests performed with other known BB R-genes revealed that the allele was distinct from others having a similar chromosomal location.
authors.affiliation: Plant Breeding, Genetics, and Biotechnology Division, International Rice Research Institute, DAPO Box 7777, Metro Manila, Philippines.|C/o IRRI-Korea Office, National Institute of Crop Science, Rural Development Administration, Iseo-myeon, Wanju-gun, Jeollabuk-do, 565-851, Republic of Korea.
authors.forename: Suk-Man
authors.initials: SM
authors.lastname: Kim
authors.affiliation: Central Area Crop Breeding Research Division, National Institute of Crop Science, Rural Development Administration, Suwon, 441-857, Republic of Korea.
authors.forename: Jung-Pil
authors.initials: JP
authors.lastname: Suh
authors.affiliation: Biosafety Division, National Academy of Agricultural Science, Rural Development Administration, Jeonju, 560-500, Republic of Korea.
authors.forename: Yang
authors.initials: Y
authors.lastname: Qin
authors.affiliation: National Institute of Crop Science, Rural Development Administration, Iseo-myeon, Wanju-gun, Jeollabuk-do, 565-851, Republic of Korea.
authors.forename: Tae-Hwan
authors.initials: TH
authors.lastname: Noh
authors.affiliation: Plant Breeding, Genetics, and Biotechnology Division, International Rice Research Institute, DAPO Box 7777, Metro Manila, Philippines.|C/o IRRI-Korea Office, National Institute of Crop Science, Rural Development Administration, Iseo-myeon, Wanju-gun, Jeollabuk-do, 565-851, Republic of Korea.
authors.forename: Russell F
authors.initials: RF
authors.lastname: Reinke
authors.affiliation: Plant Breeding, Genetics, and Biotechnology Division, International Rice Research Institute, DAPO Box 7777, Metro Manila, Philippines. k.jena@irri.org.
authors.forename: Kshirod K
authors.initials: KK
authors.lastname: Jena
mesh_terms: D032461:Chromosomes, Plant; D003433:Crosses, Genetic; D060467:Disease Resistance / Q000235:genetics*; D005787:Gene Frequency; D017343:Genes, Plant; D005819:Genetic Markers; D005838:Genotype; D058977:Molecular Sequence Annotation; D012275:Oryza / Q000235:genetics* / Q000382:microbiology; D010641:Phenotype; D020161:Physical Chromosome Mapping; D010935:Plant Diseases / Q000235:genetics*; D056910:Republic of Korea; D014974:Xanthomonas
chemical_list: D005819:Genetic Markers