【作者】 王正询； 柯德森； 杨礼香； 康国章；

【Author】 Wang Zhengxun Ke Desen Yang Lixiang Kang Guozhang College of Life Science, Guangzhou University, Guangzhou, 510006; Henan Agricultural University, Zhengzhou, 450002

【机构】 广州大学生命科学学院； 河南农业大学；

【摘要】 水杨酸能显著提高香蕉幼苗的抗寒性,我们通过mRNA差异显示法得到了几个在冷胁迫香蕉叶片内水杨酸诱导高表达的差异片段,对其中一个表达量差异最明显片段,经测序后进行同源性比较分析,没有发现同源性基因,但它与大豆在冷胁迫下高表达几个基因的部分片段(BG237672、 BG839411、BG839854等)有高度同源性,推测此片段是一个与冷胁迫有关的新基因。通过3’和5’RACE法,我们得到了此基因的cDNA全长,为1 783bp,它的CDS为1 251bp,编码了417个氨基酸,其中富含亲水性氨基酸,同源性比较结果显示,它的编码域与玉米的一个转录子 BT024164有86％的同源,与水稻的热激蛋白基因AY224432有85％的同源性,与小麦的热激蛋白基因DQ789026有85％的同源性,与黄瓜的热激蛋白基因X67695有82％的同源性,与马铃薯的热激蛋白基因X94301有81％的同源性,表明所获得的全长基因是一个热激蛋白基因。已有研究表明,除在热胁迫表达提高外,热激蛋白基因还在其它许多逆境如冷、干旱、重金属、病原菌等胁迫下高表达,是植物对逆境胁迫的一种防御机制,它可作为调控基因表达的转录因子,从而调控基因的表达,提高植物的抗逆能力。并且,我们所获得的全长基因与玉米的一个转录因子有高度同源性,因此,我们推测,所获得的全长基因可能是在冷信号转导系统中,起转录因子作用的热激蛋白基因,水杨酸诱导高表达后的热激蛋白可与所调控的目的基因启动子中的顺式作物元件相结合,诱导目的基因的表达,从而提高香蕉的抗冷性。目前,我们正在构建此基因的过表达载体,并把它转到香蕉中,通过检测转基因植株抗冷性的高低,从而推断它在水杨酸提高香蕉抗冷性中的作用。而后,通过对此基因酵母双杂交,找到此热激蛋白所作用的目的基因。更多还原

【Abstract】 Salicylic acid (SA) could improve the tolerance of banana seedling to chilling stress remarkably. We got partial sequences of several genes which were induced by SA in chilling-stressed banana seedling leaves through mRNA differential display. The expression of one of these genes was up-regulated significantly and the gene did not show any identity to previously reported sequences in banana in GeneBank database. But the gene was high homologous with several cold-related genes (BG237672, BG839411, BG839854 etc.) in soybean. Therefore, we deduced that it was a new cold-related gene. The full-length cDNA (1 783bp) was got through 3’ and 5’ RACE. It coded 417 amino acid (aa) and the hydrophilic amino acid was rich. Sequence analyse showed that the CDS of the gene had 86% homology to that of a transcription factor in maize (BT024164) and had high homology to heat shock protein in some plants such as rice (AY224432) (85%), cucumber (X67695) (82%), potato (X94301) (81%). It showed that the gene might code a heat shock protein. It has been reported that the expression of heat shock protein could be induced during kinds of stress such as chilling, drought, heavy metal, pathogens etc., including heat stress. It was a kind of defense mechanism of plant to various stresses, which modified the expression of genes acting as a transcription factor, and enhanced the tolerance of plant to stress. The gene had high homology to a transcription factor in maize. Therefore, we deduced that the gene might code a heat shock protein which acted as a transcription factor during chilling stress. SA induced the expression of the gene and then induced the expression of aim gene, thus enhanced the tolerance of banana seedling to chilling stress. For the moment, we had constructed the over-expressing vector and prepared to transform banana. Through the detection of tolerance of transgenic banana to chilling stress, we can study the function of the gene during SA enhance the tolerance of banana to chilling stress. Then, we will investigate the aim gene of the protein by yeast two-hybrid system.更多还原