【摘要】 ICE(inducer of CBF expression)是类似MYC(myelocytomatosis)的bHLH(basic helix-loop-helix)转录因子，在植物应对低温、干旱、高盐等非生物胁迫中起重要的调节作用。本研究通过qPCR分析橡胶树ICE家族成员的表达模式。结果表明：5个ICE家族成员均响应盐胁迫上调表达。在盐胁迫2 h时，HbICE2、HbICE3、HbICE4和HbICE5显著上调表达；在盐胁迫4 h时，HbICE4和HbICE5的表达量达到最大值，其中HbICE4的上调幅度最大；HbICE1在盐胁迫4 h内无显著变化，但在处理8 h时显著上调表达。过表达这5个ICE家族成员均可不同程度地提高拟南芥的耐盐性，其中过表达HbICE4的植株对盐胁迫的抗性最强，在盐胁迫下，野生型拟南芥（WT）全部枯萎，而HbICE4转化植株的存活率为96.29%，平均单株鲜重为0.03 g，平均单株干重为0.0035 g，在HbICE家族成员转化株系中均表现最高。在盐胁迫下，WT和HbICEs转基因植株的电导率均显著增加，叶绿素含量和相对含水量均显著降低，其中HbICE4转化植株的相对电导率的增加幅度最小，叶绿素含量和相对含水量的降低幅度最小。因此，HbICE4转化植株的抗盐性可能与增强膜系统的稳定性和减缓叶绿素降解和保持相对含水量有关。该研究结果对橡胶树HbICE家族成员的生物学功能有了新的认识，有望为改良农作物耐盐性提供候选靶基因。更多还原

【Abstract】 ICE(inducer of CBF expression), the MYC(myelocytomatosis)-like bHLH(basic helix-loop-helix)transcription factor, plays an important role in regulating the responses of plants to abiotic stresses such as low temperature, drought, and high salt. In this study, the expression patterns of rubber tree ICE genes were analyzed by qPCR. The expression of five HbICEs were up-regulated in rubber tree seedlings upon salt stress, HbICE2, HbICE3,HbICE4 and HbICE5 were significantly up-regulated under salt stress for 2 h. At 4 h of salt stress, the expression of HbICE4 and HbICE5 reached the maximum with the most up-regulated level of HbICE4. Under salt stress for 4–24 h,HbICE3 was significantly down regulated. The expression of HbICE1 had no obvious change before 4 h of salt stress,but increased significantly after 8 h. Therefore, all five HbICE genes may participate in the salt stress response of rubber tree. Overexpression of HbICEs, especially HbICE4, led to an enhanced salt-tolerance of transgenic Arabidopsis based on survival rate, average fresh and dry weight per plant. Under salt stress, all wild-type Arabidopsis wilted. The survival rate of HbICE4 overexpressing Arabidopsis was 96.29%, the average fresh weight per plant was 0.03 g, and the average dry weight per plant was 0.0035 g, the three growth parameters of HbICE4 overexpressing plants were the highest among the transformed strains of rubber tree HbICE genes. Compared with the physiological indexes before salt stress,the relative conductivity of WT and HbICEs transgenic plants increased significantly under salt stress, and the chlorophyll content and relative water content decreased significantly. Among them, relative conductivity increase of HbICE4 transformed Arabidopsis was the smallest, and the decrease of SPAD value(chlorophyll content) and relative water content was the smallest. Therefore, the enhanced salt-tolerance was associated with lower relative conductivity, a physiological parameter for evaluating membrane system stability, as well as higher chlorophyll content and relative water content in comparison to those of WT. Salt stress leads to the damage of plant cell membrane system, resulting in the decrease of water content, the destruction of chloroplasts and the degradation of chlorophyll. The membrane system of plants overexpressing HbICE4 was slightly damaged under salt stress, delaying the decrease of water content and the degradation of chlorophyll. Rubber tree HbICEs can not only improve the cold and drought tolerance of transgenic plants, but also improve the salt-tolerance of transgenic plants. This study would deepen the understanding of the biological function of rubber tree HbICEs, and provide candidate target genes for improving salt-tolerance of crops.更多还原