New Breeding Parents Containing Novel QTL for Rice Sheath Blight Resistance Identified by Combining Phenotypic and Molecular Characterizations

Authors: Pinson, Shannon; OARD, JAMES - LSU AG CENTER; GROTH, DON - LSU AG CENTER; MILLER, ROBERT - RICETEC, INC.; LIU, GUANGJIE - RICE RES. CTR., U OF AR; Jia, Yulin; Jia, Melissa; Fjellstrom, Robert

Submitted to: Plant and Animal Genome Conference Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 11/1/2006
Publication Date: 1/12/2007
Citation: Pinson, S.R., Oard, J.H., Groth, D., Miller, R., Liu, G., Jia, Y., Jia, M.H., Fjellstrom, R.G. 2007. New Breeding Parents Containing Novel QTL for Rice Sheath Blight Resistance Identified by Combining Phenotypic and Molecular Characterizations. [abstract]. Plant and Animal Genome Conference XV, January 13-17, 2007, San Diego, CA. Available: http://intl-pag.org/15/abstracts.

Interpretive Summary:

Technical Abstract: Rice Sheath Blight (SB) disease, caused by the necrotrophic Rhizoctonia solani Kühn, is a global and annual cause of rice yield losses. Several QTL with small individual impact must be combined to create rice varieties tolerant of SB infection because no single gene confers complete resistance. Molecular tags for SB-QTL are highly desired by breeders. Previous analysis of 300 RILs from Lemont (susceptible japonica US variety) x TeQing (resistant indica from China) revealed that TeQing contains 15 SB resistance QTL; Lemont contains three. A population comprised of 269 TeQing-into-Lemont backcross introgression lines (TILs) was obtained from IRRI to identify lines containing the mapped SB-QTL in isolation as well as in various combinations. By isolating specific TeQing genomic regions in predominantly-Lemont genetic backgrounds, these TILs allow researchers to more precisely determine the locations and genetic effects (i.e., agronomic usefulness) of the TeQing QTL. TILs were evaluated for SB resistance in 15 replications of inoculated field trials conducted 2003 - 2005 in Crowley, LA; Beaumont, TX; and Alvin, TX. Sixty-seven TILs appeared more resistant than Lemont. One hundred and eleven SSRs distributed among the 12 rice chromosomes were used to determine the QTL and background composition of each TIL. The use of molecular data identified three TILs as having exceptional breeding value in that they contain SB-QTL not previously available in US germplasm now introgressed into predominantly-Lemont backgrounds. Crosses with these TILs have been made to initiate populations for breeding purposes as well as for fine mapping and gene-tag development.