QTL analysis of rice low temperature germinability

A double haploid population, derived from anther culture of F-1 hybrid betw een a typical indica and a japonica (ZYQ8/JX17), has been used to investiga te the low temperature germinability (LTG) at 15 degreesC. The low temperat ure germinability of two parents was significantly different. In 6-11 d, th e germination percentage of ZYQ8 was higher than that of JX17. In 12-16 d, the germination percentage of JX17 was higher than that of ZYQ8. The quanti tative trait loci (QTLs) of every day for low temperature germinability hav e been mapped based on a molecular linkage map constructed from this popula tion. In 8-11 d, qLTG-9 was identified in C397B-RZ617B on chromosome 9, the additive effect was positive, showing that the allele from JX17 could incr ease low temperature germinability. In 12-16 d, qLTG-4 was mapped between R G908 and CT563 on chromosome 4, the additive effect was negative, showing t hat the allele from ZYQ8 could increase low temperature germinability. Thes e two QTLs were detected at different stages, showing the complexity of the mechanism of low temperature germinability.