Abstract:In this study, we constructed an F2 isolated population derived from a cross between a dwarf wild rice mutant with shortgrain and a cultivar variety KJ01 with longgrain. And the genetic analysis for grain length of the F2 population was performed. By using 132 pairs of polymorphic molecular markers evenly distributed on 12 chromosomes of rice, we conducted QTL mapping and major QTLs analysis, which would establish a foundation of further cloning the novel major grain length gene and provide a theoretical basis for grain shape breeding of rice. The results were as follows: (1) grain length trait of the isolated population F2 was quantitative trait controlled by multiple genes. (2) By QTL linkage analysis of 543 F2 individuals, a linkage map of 1 713.94 cM controlling rice grain length was constructed, and a total of 24 QTLs were detected, and only 3 QTLs showed additive genetic effects, the others showed negative genetic effects. (3) The three major QTLs located in interval markers of PSM379-RID24455, RID24455-RM15689, and RM571-RM16238 on chromosome 3, which explained phenotypic variation for 54.85%, 31.02%, and 7.62, respectively. (4) The grain length QTL located in interval markers of PSM379-RID24455 was the major QTL newly discovered in this study.