RESPONSE OF DIVERSE RICE GERMPLASM TO BIOTIC AND ABIOTIC STRESSES
Title: Selection for fissure resistance now made possible in early breeding generations
Submitted to: Experiment Station Bulletins
Publication Type: Experiment Station
Publication Acceptance Date: July 1, 2009
Publication Date: July 9, 2009
Citation: Pinson, S.R., Gibbons, J., Jia, Y. 2009. Selection for fissure resistance now made possible in early breeding generations. Texas Rice, Highlighting Research in 2009. pp. VI-VII.
Rice kernel fissuring is one of the leading causes of milling yield losses. Any reduction in fissuring can result in direct increases in yield and profit for both producers and millers. While most U.S. rice varieties yield around 55% head rice, the fissure-resistant varieties ‘Cypress’, ‘Saber’ and ‘Cybonnet’ typically yield 61% head rice. For a producer yielding 7000 lb/acre paddy, even such a small (5%) improvement in milling yield can increase profits by $18/acre. Breeders would like to select for fissure resistance, but cannot select for a trait unless they can see or detect it. Unfortunately, the most reliable method breeders have had for evaluating fissure resistance requires high amounts of seed, labor, and field space, and cannot be conducted until late in the breeding process, after much breeding effort has already been expended. In order to achieve rapid breeding gains, breeders need instead a proactive selection method that allows them to select for a desired trait in early breeding generations.
We have developed a new method that allowed us to accomplish, for the first time ever, successful selection for fissure resistance (FR) among F2 plants (the very 1st breeding generation). This laboratory method uses small samples of seed (50 to 100 kernels) that are evaluated for fissure rates after controlled exposure to humid laboratory conditions. In 2006, in-lab fissure inductions were used to select for both fissure resistance (FR) and susceptibility (FS) among 300 Cypress x LaGrue F2 plants. The success of the selections was measured the following year by comparing the response of the resulting progeny populations. The fact that the progeny from FR selections were significantly more fissure-resistant in 2007 than the progeny from the FS selections documented that the F2 selections were successful. A second round of selection was imparted to the still-segregating F3 progeny. The fact that some FR selections yielded both FR and FS progeny in 2008 suggests that FR is genetically dominant over FS. It also appears that a gene for FR may be linked to the semidwarf gene, known to reside on chromosome 1.