Transcriptome analysis of OsOAT in cold response at booting stage in rice

Cold stress is a major factor limiting production and geographical distribution of rice varieties. However, the molecular mechanisms underlying cold tolerance remain to be elucidated. Here, we report that ornithine delta-aminotransferase (OsOAT) contributes to cold tolerance during both vegetative and reproductive development. osoat mutant was identified as a temperature-sensitive male sterile mutant with deformation of floral organs and seedlings sensitive to cold. Comparative transcriptome analysis showed that osoat mutation and cold treatment of the wild-type plant induced similar patterns in global gene expression profiles in the anthers. OsOAT genes in indica rice Huanghuazhan (HHZ) and japonica rice Wuyungeng (WYG) are different in gene structure and response to cold. OsOAT is cold-inducible in WYG but cold-irresponsive in HHZ. Further studies showed that indica varieties carry both the WYG-type and HHZ-type of OsOAT, while japonica varieties mostly carry the WYG-type. Cultivars carrying the HHZ-type OsOAT are mainly distributed in low latitude regions, while varieties carrying the WYG-type OsOAT are distributed in both low and high latitude regions. Indica varieties carrying the WYG-type OsOAT generally have higher seed-setting rates than those carrying the HHZ-type under cold stress during booting stage, suggesting a favorable selection of the WYG-type OsOAT during domestication and breeding to cope with low temperature.