Cloning and initial characterization of low-temperature germination- and post-germination growth-associated gene

Abstract

English abstract Low-temperature is an important factor determining germination of rice, but the underlying genetic mechanisms of low-temperature germination(LTG) have not been well elucidated. We constructed a genetic map using recombinant inbred lines derived from a cross Kakehashi(Japanese cultivar) x DunghanShali(European cultivar) in order to locate quantitative trait loci(QTLs) conferring LTG. Three LTG QTLs derived from DunghanShali were mapped. Sequence analysis of QTL region in chromosome 3 identified a base substitution between the parents in a gene coding for a transcription factor containing Histone-like motif. Arabidopsis knockout-mutants with defect in the homologue of this transcription factor gene showed a delay in germination both under normal and cold temperatures. Knockout-mutants also showed slow post-germination growth under cold condition. These observations in Arabidopsis mutants parallel the slow germination of the Japanese cultivar rice in low temperature. Therefore, loss-of-function of this particular gene may cause inefficient LTG in the Japanese cultivar rice.