Submitted to: Rice Technical Working Group Meeting Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 2/1/1996
Publication Date: N/A
Technical Abstract: Source-sink relationship largely determines grain yields in cereal crops. Using RFLP analysis and F4 progeny from 'Lemont'/'Teqing', we located quantitative trait loci (QTLs) and epistatic loci influencing the following component traits of source size, sink size, and yield: Length and width of the flag leaf and of the second leaf, panicle length, floret density, floret number per panicle, spikelet sterility, kernel weight, grain number per panicle, and grain weight per panicle. A total of 32 QTLs affecting source and sink traits were identified. These QTLs explained between 29 to 43 percent of the observed variation for each character and mapped to 10 of the 12 rice chromosomes. QTLs affecting leaf shape but not size were less correlated with sink size and/or capacity than were the QTLs that affected both leaf shape and size. QTLs which affected panicle length and floret density were also associated with primary sink size (floret number) but not twith sink capacity (grain number and grain weight per panicle) - possibly due to competition for limited resources (carbohydrates) causing increased sterility. The majority of genes determining the sink size in rice were also associated, possibly pleiotropically, with source size. Thus, genetic improvement of grain yield and its components may be more efficiently achieved by manipulating (via linked DNA markers) genes which have large effects on source size (i.e. leaf size) than those associated with primary sink size (panicle length and floret density).