Analyzing quantitative trait loci for yield using a vegetatively replicated F-2 population from a cross between the parents of an elite rice hybrid

Although F(2)s are the most informative populations for genetic analysis, i t has been difficult to use F-2 populations directly for QTL analysis becau se it is usually difficult to assess the reliability of the data, due to an inability to estimate the experimental errors. In this study, we performed a QTL analysis for yield and yield-component traits of an F-2 population b ased on data from replicated field trials over 2 years using vegetative sho ots of ratooned plants, making use of the ratooning habit of rice. The obje ctive of this study was to explore the possibility of conducting QTL analys es directly based on an F-2 population by means of ratooning plants. The ex perimental population was from a cross between 'Zhenshan 97' and 'Minghui 6 3', the parents of 'Shanyou 63', an elite rice hybrid widely grown in China . Agenetic linkage map containing 151 molecular markers was constructed for QTL I napping. A total of 20 distinct QTLs were detected. eight of these w ere detected in both years and remaining 12 in only 1 year. Compared with t he results of our previous analysis of the F-2:3 families from the same cro ss, it was shown that most of the QTLs detected in the ratooned F-2 populat ion were also detected in the F-2:3 population. However, the estimates of b oth additive and dominant types of genetic effects for many of the QTLs bas ed on F-2 ratoons were substantially larger than those based on F-2:3 famil ies. The results indicate that vegetatively ratooned F-2 populations may ha ve considerable utility in the mapping of QTLs, especially if dominant type s of gene actions are of concern, although there were certain technical lim itations in making use of such populations in the experiments.