Cold stress is the limiting factor of rice growth and production, and it is important to clone cold stress tolerant genes and cultivate cold tolerance rice varieties. The MADS transcription factors play an important role in abiotic stress signaling in rice. This study showed that OsMADS25 was up-regulated by low temperature and abscisic acid (ABA), suggesting that OsMADS25 may be involved in ABA-dependent signaling. The OsMADS25 overexpression vector, pCambia1300-221-OsMADS25-Flag, was constructed and introduced into the rice variety Zhonghua 11 (ZH11) through Agrobacterium tumefacian-mediated genetic transformation. Two homozygous lines with high expression levels were selected for phenotypic identification. OsMADS25 overexpression lines show significantly improved cold stress tolerance and the sensitivity to ABA at the seedling stage of rice. Reactive oxygen species (ROS) was detected by diaminobenzidine (DAB) staining and nitroblue tetrazolium (NBT) staining. After treatment with cold stress, little ROS accumulation was observed in OsMADS25 overexpression lines compared to wild-type ZH11. In conclusion, OsMADS25 plays a role in scavenging reactive oxygen species (ROS) and could improve rice tolerance to cold stress involved in ABA-dependent pathway.
低温冷害是影响水稻高产的关键环境因素,鉴定和克隆具有重要应用价值的耐低温基因并培育耐低温新品种对于保障粮食安全具有重要意义。MADS转录因子在植物逆境信号途径中扮演着重要的角色。本研究利用qRT-PCR检测,发现OsMADS25受低温和脱落酸(abscisic acid, ABA)诱导表达上调,预示OsMADS25可能参与ABA依赖的逆境信号途径。进一步构建了水稻OsMADS25 的过表达载体pCambia1300-221-OsMADS25-Flag,利用根癌农杆菌介导的遗传转化法将其导入水稻品种中花11 (ZH11),选取两个表达量高的纯合株系进行表型鉴定。结果表明,OsMADS25过表达株系显著提高了水稻苗期对低温的耐受性以及对ABA的敏感性。利用3,3-二氨基联苯胺(diaminobezidine, DAB)和氯化硝基四氮唑蓝(nitrotetrazolium blue chloride, NBT)组织化学染色结果表明：低温处理后,OsMADS25过表达株系比野生型ZH11染色浅,表明过表达株系在低温胁迫下积累的活性氧(reactive oxygen species, ROS)相对较少,增强了对低温的耐受性。综合结果表明,低温逆境下OsMADS25响应ABA信号,通过提高水稻对ROS的清除能力,避免水稻受到低温伤害。.
Keywords: OsMADS25; abscisic acid (ABA); cold tolerance; reactive oxygen species(ROS); rice (Oryza sativa L.).