Interaction of Xa genes in different maintainer line background to historical and contemporary races of Xanthomonas orazae pv. oryzae

• Published in: Journal of Tropical Plant pathology (Philippines) Vol. 39; no. 1
• Main Author: Briones, L.M.(Leyte State Univ. Visca Baybay, Leyte (Philippines). Redoña, E.D., Natural, M.P., Vera Cruz, C.M., Leung, H.)
• Format: Journal Article
• Language: English
• Published: 01.01.2003
• Subjects: disease resistance; GENE; genes; Oryza sativa; RESISTANCE AUX MALADIES; RESISTENCIA A LA ENFERMEDAD; VARIEDADES; VARIETE; varieties; xanthomonas oryzae
• ISSN: 0115-0804

Simple major genes usually confer resistance of certain rice varieties against bacterial blight. Combining major resistance genes in a variety (gene pyramiding) is said to provide higher level of resistance. Four maintainer (B) lines used for hybrid rice breeding with introgressed single and combination of Xa4 and Xa7 genes were inoculated with two historical (race1-PX061 and race 2-PX086) and three contemporary races (race 3-PX0340, race 9-PX0339 and race 10- PXO341) of Xanthomonas oryzae pv. oryzae, to: 1)determine the reaction of individual or combination of these genes to the different pathogen races, 2)determine the effect of line background to the expression of the genes, and 3)detect possible gene interactions in conferring resistance to a particular race. The Xa4 and Xa7 genes in IRBB4/7 (control) and in the four maintainer background (IR58025, IR62829, Lian B, and 913 B, either singly or in combination, provided the expected reaction t o the diagnostic races line. Xa-4-resistant to race 1 and Xa7-resistant to race 2). All the lines with both Xa4 and Xa7 showed shorter lesions and provided resistance to more races than those containing single genes. Xa4 and Xa7 genes together in diferent maintainer background, however, imparted a complementary gene action by conferring a higher level of resistance to race 3-(PX0340) and to race 10 (PX0341) in Lian B background. By examining the reaction of these genes in the four B lines to race 9 (PX0339), a segragation of an unknown resistance gene in IR58025B, IR62829B, and 913B was observed which was not detected previously using the diagnostic races that differentiate Xa4 and Xa7. Conference of the Pest Management Council of the Philippines Cebu City, Philippines 6-9 May 2003