Minig Novel Genes Resistant to Blast Disease for US Rice Production.

Rice blast disease is one of the most damaging and prevalent diseases in the southern U.S. The Pi-ta resistance gene that conveys resistance to numerous races has been used in rice production for about 20 years, but is overcome by several new races including IB-33 and IE-1k. Banks is a high yielding long-grain cultivar which contains the Pi-ta gene. In 2004, about 20 acres of a Banks field in Arkansas were severely damaged by rice blast and the damage was determined to be caused by race IE-1k. This demonstrates that new gene(s) resistant to these new races are urgently needed and breeders are constantly faced with the challenge of pyramiding disease resistance genes to maintain production stability. Chinese cultivars ‘4484’ and ‘Shufeng 121’ in the USDA rice germplasm collection (www.ars-grin.gov) were determined to be resistant to 11 races of blast common to the southern U.S., including races IB-33 and IE-1k. Molecular marker analysis has revealed that the resistance is not due to previously described resistance genes: Pi-ta, Pi-b, Pi-k and Pi-z. The apparently novel resistance genes in these germplasms could be effective to some of these new races. These Chinese cultivars have proven to be well adapted to the southern U.S. and have good yield, milling, and long grain cooking qualities. The combination of novel resistance genes along with elite traits of economic value in these Chinese cultivars makes them valuable materials to be used in the U.S. for blast control and rice production.