DEVELOPMENT AND CHARACTERIZATION OF GENETIC RESOURCES FOR AGRONOMIC AND QUALITY TRAITS USING GENOMIC TOOLS
Location: Dale Bumpers National Rice Research Center
Title: Test of Some Hybrid Combinations to Rice Blast
Submitted to: Symposium Proceedings
Publication Type: Proceedings
Publication Acceptance Date: August 5, 2010
Publication Date: August 12, 2010
Citation: Yan, Z., Lee, F., Yan, W., Mcclung, A.M., Deren, C. 2010. Test of Some Hybrid Combinations to Rice Blast. Symposium Proceedings. IV-P-99.
Rice blast disease caused by Magnaporthe oryzae is one of the most devastating rice diseases worldwide. Blast resistant cultivars are recognized as the most efficacious and economical way to control this disease. Genetic resistance to rice blast is generally governed by a few major genes, often in combination with partial resistance genes. Multiple blast resistant cultivars have been released and utilized in the southern US. However, the blast pathogen is highly adaptable and new blast races have quickly evolved as resistant cultivars were utilized in rice production. For example races IB-1, IB-49, IC-17, and IG-1 are the most common in the southern US. The cultivar Katy, containing the Pi-ta gene, was released as resistant to these common races. However, a new virulent race IE-1k emerged to attack cultivars possessing Pi-ta.
Recently, breeders have endeavored to combine blast resistance genes and introduce new sources of resistance for the deployment of new cultivars that have broader spectrum resistance in the
Hybrid breeding is accepted as a new way to improve yield and blast resistance for rice production in the southern US. Thirty hybrid rice combinations and selected parents were evaluated for reaction to a bulk spore suspension of seven common blast races including IE-1, IB-1, IH-1, IG-1, IB-49, IC-17 and IE-1k in greenhouse tests conducted at the University of Arkansas Rice Research and Extension Center (RREC), near Stuttgart, Arkansas in the Spring of 2010. Seedlings were inoculated at the four-leaf stage by spraying with 16 × 104 to 22 × 104 spores mL-1. The inoculated plants were held in the chambers with over 90% humidity at about 25º C for 18-24 hours, then moved to the greenhouse at 28º to 35º 'C. Disease reactions were determined 7 days after inoculation when typical blast lesions appeared on the leaves of
susceptible checks. The Arkansas RREC Blast Leaf Rating Scale System (0 to 9 scale) was used to determine disease reactions. Nine rice combinations and 7 parents were found to be resistant
to the mixture of the seven blast races. The resistant rice combinations and parents will be evaluated for subsequent hybrid rice development and progress will be presented