Title: Oryza rufipogon introgressions improve yield in the U.S. cultivar Jefferson Authors
Submitted to: Symposium Proceedings
Publication Type: Proceedings
Publication Acceptance Date: September 30, 2009
Publication Date: November 15, 2009
Repository URL: http://www://iirx-gallery.com/coedmiirx/Charmaine/6th%20International%20Rice%20Genetic%20-%20Complete%20Poster%20Abstracts%5BBatch%205%5D.pdf
Citation: Kimball, J.A., Moon, S., Mccouch, S.R., Mcclung, A.M. 2009. Oryza rufipogon introgressions improve yield in the U.S. cultivar Jefferson. Symposium Proceedings. P9-24. Technical Abstract: An advanced backcross (BC2) population was developed to explore the breeding value of the wild ancestral species O. rufipogon (IRGC 105491) in a cross with the tropical japonica US variety, cv Jefferson. Early generation selection eliminated lines which possessed undesirable traits such as dormancy, shattering, and red bran attributed to the wild species. Six QTLs, averaging 10-12Mb in size and located on chromosomes 1, 2, 3, 6, 8, and 9, were evaluated in 4 to 12 near isogenic lines (NILs). Replicated yield trials were conducted in eight flooded and two aerobic environments. Four NILs possessing an introgressed region from chromosome 2 and two NILs possessing an introgressed region on chromosome 6 had significantly higher yield than the parental cultivar Jefferson under flooded conditions. NIL 43-1-2 (QTL 2.1) averaged 23% higher yield than Jefferson under flooded conditions. Although there were few significant differences under aerobic conditions, six of the entries with the highest yield possessed QTL 2.1. Regression analysis demonstrated that the O. rufipogon introgression explained 40% and 64% of the variation for yield under flooded and aerobic conditions, respectively. Panicle length explained 18% of the variation for yield under flooded conditions whereas tiller number explained 25% of the variation in the aerobic trials. Although wild Oryza species are well-known as a source of pest resistance, this study demonstrates the yield enhancing value of O. rufipogon. We are validating the yield improvement of these NILS in yield trials conducted throughout the southern U.S. and are proceeding with additional backcrossing to develop NILs for fine-mapping.