玉米分子伴侣基因ZmBiP2在逆境下的功能分析

BiP(binding protein)基因编码的蛋白是一类重要的分子伴侣,在动植物的逆境胁迫响应过程中具有重要的作用。从玉米抗旱自交系旱21中分离到分子伴侣基因ZmBiP2,序列分析结果显示,该基因开放阅读框长1989 bp,编码含663个氨基酸的蛋白,包含热激蛋白家族特有的TVIGIDLGTTYSC保守结构域和ATP结合位点。实时荧光定量PCR结果显示,Zm Bi P2基因在玉米的雄穗和子房中表达量最高;在盐、甘露醇胁迫条件下,该基因在植株的地上部分上调表达。过量表达Zm Bi P2基因的拟南芥转基因株系在种子萌发时期对盐和甘露醇胁迫的耐受能力减弱,在苗期对盐胁迫敏感。推测在植物响应非生物胁迫的过程中,过量表达的ZmBiP2蛋白可能发挥负调节蛋白的功能。

Cloning of a Maize Molecular Chaperone Gene,ZmBiP2, and Its Functional Analysis under Abiotic Stress

BiP gene, coding an important molecular chaperone, plays an important role in response to stress conditions. In our study, ZmBiP2 gene was identified and characterized in maize “Han21” inbred line. ZmBiP2 gene has an ORF of 1989 bp and encodes a protein containing 663 amino acids. The deduced protein of ZmBiP2 was predicted to contain a TVIGIDLGTTYSC domain, which was highly conserved in HSP70 protein family, and an ATP-binding site. Real-time quantitative PCR analysis revealed that ZmBiP2 gene had different expression patterns in different organs, with the high expression level in tassel and ovaries. Under mannitol and NaCl stress conditions, ZmBiP2 showed an up-regulated expression in shoots. Overexpression of ZmBiP2 in Arabidopsis showed hypersensitivities to mannitol stresses at the germination stage. Overexpression of ZmBiP2 in Arabidopsis conferred hypersensitivities to salt stress at both germination stage and seedling stage. These results suggested that overexpression of ZmBiP2 might function as a negative protein in response to abiotic stresses.