Submitted to: Rockefeller Foundation Proceedings
Publication Type: Proceedings
Publication Acceptance Date: June 1, 1999
Publication Date: N/A
Technical Abstract: The development of hybrid rice and the use of high yielding foreign germplasm to develop new cultivars have been hindered by low milling quality (MQ). It is difficult to select for MQ early in the breeding process because of segregation for kernel morphology and chemistry and because of the large impact variable macro- and micro-environments have on this trait. The purpose of this research was to identify genomic regions associated with MQ and with aspects of kernel morphology and chemistry known or hypothesized to be associated with milling quality in order to clarify the relationships between these kernel traits and MQ, and to identify molecular markers breeders can use for selecting for improved MQ. A population of 284 recombinant inbred lines (RILs) was developed from a Lemont x Teqing cross and characterized for 175 RFLP probes. Seed samples carefully harvested from two 1997 field replications were characterized for rkernel shape (length, width, thickness, and length/width ratio) and MQ as indicated by percent whole kernels after milling using a standard milling process. Interval mapping identified a total of eight chromosomal regions associated with MQ, two of which are of particular interest to us because they are apparently independent from grain shape, and may be affecting grain hardness. These two loci each accounted for 6-8% of the total variance observed in percent head rice in 1997. This would translate into a 4% increase in head rice resulting from the incorporation of a single gene into a new variety which would result in on-farm income of $9.50 per acre. Thus, control over genes such as the two shape-independent MQ loci identified here can significantly benefit U.S. rice producers. Data collected from 1998 seed will be used to verify these putative QTLs.