GENOMIC CHARACTERIZATION OF RICE GERMPLASM
Location: Dale Bumpers National Rice Research Center
Title: Identification of Novel Blast Resistance Genes in Rice Cultivar Zhe733
Submitted to: Rice Technical Working Group Meeting Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: January 1, 2006
Publication Date: February 15, 2006
Citation: Wamishe, Y., Jia, Y., Jia, M.H., Liu, G. 2006. Identification of novel blast resistance genes in rice cultivar zhe733 [abstract]. In: Rice Technical Working Group Meeting Proceedings, February 28, 2006 - March 1, 2006, Houston, Texas. 2006. CDROM.
Blast disease caused by the fungus Magnaporthe grisea remains a serious threat to rice production in the U.S. Use of resistant cultivars is the most economic and efficient method to control blast disease. Rice has major genes conferring resistance to M. grisea races containing the corresponding avirulence genes. For blast control, rice breeders have long been incorporating new resistance genes from diverse genetic resources into their advanced breeding lines. In the Southern US, a major gene, Pi-ta, confers resistance to a broad range of predomiant US races (IB1, IB49, IB54, IB 45, IH1, IG1, IC-17 and IE1), and the Pi-ta gene was incorporated into several elite US rice cultivars, Katy, Madison, Drew, Kaybonnet, Cybonnet, and Ahrent through conventional plant breeding. DNA markers for Pi-ta were also developed to assist conventional breeding by marker-assisted selection.
M. grisea is known to reproduce asexually in the fields, and the change of avirulence genes often defeats the corresponding major resistance genes. Thus, M. grisea regain the ability to infect rice cultivars. In 2004, an IE1k type of virulent isolate that attacked a resistant new cultivar, Banks, resulted in significant economic damage in Arkansas. Zhe733, a Chinese indica cultivar confers resistance to IE-1k, and also confers resistance to the above-mentioned races. Zhe733 has been used to introduce new resistance into advanced breeding lines in the US.
To map these resistance genes in Zhe733, 353 F10-11 recombinant inbred lines (RILs) from a cross of Zhe733 and Kaybonnet low phytic acid mutant lpa1-1 were used. A ratio of 3 resistant to 1 susceptible in RILs to IE1K suggests the presence of two resistance genes in Zhe733. To confirm the presence of two resistance genes in Zhe733, an F2 population of 256 individuals of the cross of Zhe733 and C101A51 was used. A ratio of 15 resistant to 1 susceptible to IE1K thus verified our two-gene model. To identify DNA markers for marker-assisted selection, 126 polymorphic SSR markers were identified and used for bulk segregant analysis. Progress in marker analysis and mapping status is reported.