Rice bacterial blight, caused by Xanthomonas oryzae pv, oryzae (Xoo), is one of the most serious rice diseases worldwide, A rice gene, Xa26, conferring resistance against Xoo at both seedling and adult stages was isolated by map-based cloning strategies from the rice cultivar Minghui 63, Xa26 belongs to a multi-gene family consisting of four members, It encodes a leucine-rich repeat (LRR) receptor kinase-like protein and is constitutively expressed, Sequence analysis revealed that IRBB3 and Zhachanglong lines that are resistant to a broad range of Xoo strains, also carry Xa26, However, significant difference in lesion length was observed among these lines after inoculation with a set of Xoo strains, Moreover, transgenic plants carrying Xa26 showed enhanced resistance compared with the donor line of the gene in both seedling and adult stages, These results suggest that the resistance conferred by Xa26 is influenced by the genetic background.

Bacterial blight, caused by Xanthomonas oryzae pv. oryzae, is a seriousdisease of rice worldwide. A new dominant gene for bacterial blightresistance in rice, Xa25(t), was identified from Minghui 63, a restorerline for a number of rice hybrids that are widely cultivated in China. Thisgene conferred resistance to Philippine race 9 (PXO339) of X. oryzae pv.centromericregion of chromosome 12, 2.5cM from a disease resistance genehomologoussequence, NBS109, and 7.3cM from a restriction fragmentlength polymorphism marker, G1314. The genomic location of this geneis similar to the previously identified blast resistance genes, Pi-ta andPi-ta2.

Bacterial blight, caused by Xanthomonas oryzae pv. oryzae, is a seriousdisease of rice worldwide. A new dominant gene for bacterial blightresistance in rice, Xa25(t), was identified from Minghui 63, a restorerline for a number of rice hybrids that are widely cultivated in China. Thisgene conferred resistance to Philippine race 9 (PXO339) of X. oryzae pv. oryzae in both seedling and adult stages. It was mapped to the centromericregion of chromosome 12, 2.5cM from a disease resistance genehomologoussequence, NBS109, and 7.3cM from a restriction fragmentlength polymorphism marker, G1314. The genomic location of this geneis similar to the previously identified blast resistance genes, Pi-ta andPi-ta2.

Bacterial blight caused by Xanthomonas oryzaepv oryzae is a devastating disease in rice worldwide.The resistance gene Xa4 has been widely used in breedingprograms and played an important role in protectingrice from this disease. Using 642 highly susceptible individualsand a random sample of 255 individuals from anF2 population developed from a cross between IRBB4and IR24, the Xa4 gene was genetically mapped to aregion less than 1 cM. A contig map was constructed forthe Xa4 region consisting of six non-redundant bacterialartificial chromosome (BAC) clones and spanning approximately500 kb in length. Analysis of recombinationevents in the Xa4 region located the gene locus to oneBAC, 3H8. Assay of the recombinants using the subclonesof 3H8 in combination with sequence analysisfurther narrowed the Xa4 locus down to a 47-kb fragment.

The inheritance of resistance for bacterialblight, caused by Xanthomonas oryzae pv. oryzae (Xoo),was studied in Minghui 63, an elite restorer line for anumber of widely used rice hybrids in China. A newdominant gene against a Chinese Xoo strain JL691 in boththe seedling and adult stages was identified in Minghui 63and designated as Xa26(t). Using a total of 477 highlysusceptible individuals from an F2 population, the Xa26(t)locus was mapped to a region of about 1.68 cM. Thislocus co-segregated with marker R1506 and was 0.21 cMfrom marker RM224 on one side and 1.47 cM frommarker Y6855RA on the other side, in rice chromosome11. A contig map, composed of five non-redundantbacterial artificial chromosome (BAC) clones and spanningapproximately 500 kb in length, was constructed.Analysis of recombination events in the Xa26(t) regionwith the highly susceptible F2 individuals anchored thegene locus to a region covered by three overlapped BACclones. Assay of the lines showing a double crossover inmarker loci flanking Xa26(t), in a population of recombinantinbred lines carrying Xa26(t), further delineatedthe gene to a 20-kb fragment. The Xa26(t) locus is tightlylinked to another bacterial blight resistance gene locus,Xa4.