|GIBBONS, JAMES - Rice Research And Extension Center|
Submitted to: Agricultural Experiment Station Publication
Publication Type: Experiment Station
Publication Acceptance Date: 6/3/2011
Publication Date: 6/28/2011
Citation: Pinson, S.R., Gibbons, J., Jia, Y. 2011. Breeding for rice fissure resistance made possible through development of a new selection technique and identification of molecular gene tags. Texas Rice Special Section, Highlighting Research in 2011. p. II.
Technical Abstract: Value: One of the primary causes of rice grain breakage during milling is fissuring, or cracking, of the rice before it enters the mill. Any reduction in kernel fissuring can result in direct increases in profit for both producers and millers. For a producer yielding 7,000 lb/A paddy, even a small (5%) improvement in milling yield can increase profits $18/A. Finding genes: Some rice varieties produce grain more resistant to fissuring than others, and breeders would like to incorporate these genes into improved rice varieties. While most U.S. rice varieties yield around 55% head rice, Cypress, Saber, and Cybonnet typically yield 60 to 65% head rice. Cybonnet inherited its fissure-resistance genes from Cypress, but Saber appears to have a different genetic mechanism allowing its kernels to resist fissuring when exposed to humidity. Improved Selection Technique: Traits that can be selected for in the early generations of the breeding process are easier and cheaper to select for than traits that cannot be seen until late in the breeding selection process. Recently, successful selection for fissure resistance was accomplished, for the first time ever, using a laboratory evaluation method wherein rates of kernel fissuring are observed after exposure of 50-kernel samples to 100% relative humidity under controlled laboratory conditions. We used this method to select among 300 Cypress x LaGrue F2 progeny. Improved fissure resistance in the following F3 and F4 generations documented the success of the selections, and opens new opportunites for rice breeders to more effectively develop new fissure-resistant US rice varieties. Tagging Genes with Molecular Markers: The effective phenotyping provided by this lab method was used to identify molecular gene tags associated with fissure resistance genes. One gene from Cypress was found on chromosome 1, another on chromosome 8. Breeders can now use these molecular gene-tags markers to select for Cypress-like fissure resistance. Studies to identify genes for Saber-like resistance are ongoing.