Submitted to: Rice Technical Working Group Meeting Proceedings
Publication Type: Proceedings
Publication Acceptance Date: February 1, 1996
Publication Date: N/A
Grain shape affects cooking, eating, milling and processing character, thereby affecting the market price commanded by a rice variety. Grain shape is also associated with yield potential, grain size and kernel weight. To better understand the inheritance of grain shape and size, we conducted RFLP analysis of a 'Lemont'/'Teqing' population. Gene numbers, effects and chromosomal locations were determined using Mapmaker/QTL and standard ANOVAs to correlate F2 breeding values for observed grain characters with F2 data on 115 marker loci. Grains were obtained from seven to ten F4 panicle rows per 255 ancestral F2 plants that were grown in family groups in the field. Two rows of 'Gulfmont', a sister line of Lemont, was placed between each family-grouping of F4 sibling rows to provide a measure of environmental effect. One panicle from 10 different plants per F4 row were harvested and threshed together, mixing their seed for kernel measurement. F2 breeding values for length, width, length/width ratio, and kernel weigh were the mean of the values for the seven to ten F4 progeny rows per F2 family. The variance of the measurements between the kernels within a single F4 sample provided a measure of within row variability. The variance of the related row means provided a measure of within family variation. Fourteen chromosomal regions containing QTLs affecting grain shape and/or size were located on nine of the 12 rice chromosomes. F4 progeny lines derived from F2 plants that were heterozygous for QTLs exhibited higher between-row variability than those derived from homozygous F2 plants, providing additional evidence of the putatively identified QTLs. As was expected from their integral relationships, grain shape, size, and weight QTLs were often but not always located in similar chromosomal regions.