ARS | Publication request: Straighthead resistance is controlled by two dominant and additive genes in rice

Submitted to: ASA-CSSA-SSSA Annual Meeting Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: July 1, 2009
Publication Date: November 4, 2009
Citation: Li, X., Agrama, H.A., Correa, F., Yan, W., Wu, D. 2009. Straighthead resistance is controlled by two dominant and additive genes in rice [abstract]. Proceedings of 2009 International Annual Meetings of ASA-CSSA-SSSA, November 1-5, 2009, Pittsburgh, Pennsylvania. CDROM.

Technical Abstract: Straighthead is a physiological disorder and causes grain sterility, which could result in complete yield loss when it is severe in rice. Most U.S. cultivars are susceptible to the disorder and water management is used for its prevention although it increases production costs. Genetic understanding of straighthead resistance is the primary step for breeding new cultivars resistant to this disorder and improving production efficiency. A previous study has identified forty-two resistant cultivars that have no yield reduction under conditions where severe straighthead symptoms were observed in susceptible materials. Two resistant cultivars, Zhe 733 (PI 629016) and Jing185-7 (PI 615205) from China were crossed with the susceptible cultivars R312 (PI 614959) and Cocodrie (PI 606331), respectively, for genetic study. R312 is from China and Cocodrie is popularly grown in the southern U.S. In 2007, 10 plants of each F1 and 300 F2 individuals for each of the two populations were evaluated for straighthead disorder induced using monosodium methanearsonate (MSMA). The F2 inferred genotypes were determined by their corresponding F3 families evaluated in 2008. Segregation ratio of 9 resistant : 6 intermediate : 1 susceptible individuals was true in both populations with Chi square=2.41, P = 0.343 in Zhe733/R312, and Chi square = 2.993, P = 0.224 in Cocodrie/ Jing185-7. The results demonstrate that straighthead resistance is controlled by two genes in additive action with resistance being dominant. As a next step, recombinant inbred lines (RIL) are being developed from the populations for further genomic characterization of straighthead resistance in order to assist breeding with molecular means.