【作者】 李彦龙；

【导师】 赵惠贤； 童依平； 李振声；

【作者基本信息】 西北农林科技大学 ， 生物化学与分子生物学， 2006， 硕士

【摘要】 IPS(induced by Pi starvation)是植物对缺磷反应非常敏感和特异的一类非编码蛋白基因,克隆小麦的IPS基因有助于了解小麦高效利用土壤磷元素的分子机理和实现小麦磷营养状况的分子诊断,本研究通过大麦(Hordeum vulgare)与小麦(Triticum aestivum L.)的比较基因组学策略克隆了5个小麦IPS基因,其中3个为TaIPS1基因(TaIPS1.1, TaIPS1.2 and TaIPS1.3),2个为TaIPS2基因(TaIPS2.1 and TaIPS2.2)。用半定量RT-PCR方法分别对TaIPS的缺磷诱导特性和缺氮或/和缺磷反应进行了研究,并结合分根实验分析了TaIPS基因表达的信号控制,还比较了两个不同小麦品种TaIPS1基因的表达情况和品种间的磷效率差异,最后利用中国春缺失系对小麦TaIPS1基因进行了染色体物理定位。实验结果如下:小麦TaIPS1基因具有22个非常保守的核苷酸,没有内含子,编码框很小,属于典型的TPSI1/MT4基因家族,该基因的表达受缺磷特异诱导,不受钾、铁、镁等其它营养元素的影响。TaIPS1基因对缺磷反应强烈并被缺氮所抑制,TaIPS2基因对缺磷反应较弱但不受缺氮影响。小麦TaIPS基因在根系中的缺磷诱导作用比地上部强烈,但地上部亦存在缺磷响应较强的TaIPS1.1基因,在小麦幼苗出现缺磷症状之前就可以明显检测到TaIPS1.1基因的诱导。TaIPS1.1/2和TaIPS1.3基因的表达模式不同,TaIPS1.3在小麦根系属于缺磷诱导性表达而到了叶片则成为组成性表达。TaIPS1基因的表达主要是受局部缺磷信号的控制而非植株系统信号所控制,局部根系磷含量越低TaIPS1表达量越高。与“京411”相比“小偃54”是一个磷高效基因型,在低磷环境下“小偃54”比“京411”表现出较高的根系磷利用效率、根系干物重、分蘖数和和较低的叶片花青素含量。基因TaIPS1.1和TaIPS1.2在“小偃54”的根系和叶片中不论是高磷环境还是低磷环境均表达,而在“京411”中只是低磷环境下表达,而且同一供磷水平下TaIPS1.1和TaIPS1.2基因在磷高效小麦品种“小偃54”中的表达量总是高于磷低效小麦品种“京411”,但TaIPS1.3基因在两个品种之间没有明显差异。“中国春”缺失系的基因定位结果显示,三个TaIPS1基因全部位于小麦第4号染色体的长臂末端。小麦TaIPS基因对缺磷反应的专一性、敏感性及在不同磷效率小麦当中的不同表达调控模式,能够为磷高效小麦种质资源的筛选、小麦磷营养的遗传改良、新品种培育及小麦磷营养高效利用的分子机理研究提供有用的线索和帮助。更多还原

【Abstract】 IPSs (induced by Pi starvation)are non-protein coding genes, which respond rapidly and specifically to phosphorous (P) deficiency. Analysis of IPS genes of wheat (Triticum aestivum L.) will enhance the understanding of the genetic response to P starvation and the developing of molecular diagnosis of P deficiency in wheat. In this study, through comparative genomics strategy between wheat and barley(Hordeum vulgare), three TaIPS1 genes (TaIPS1.1, TaIPS1.2 and TaIPS1.3) and two TaIPS2 genes (TaIPS2.1 and TaIPS2.2) were cloned in wheat. The genes specific character on P deficiency, and interaction of N with P were specially studed using RT-PCR. The signal regulation of TaIPS1 genes were analysized also by divided-roots experiment. Besids, phosphate efficiency and the expression of TaIPS1s were compared in two wheats, and the genes were finally physically located on the chromosomes of wheat“Chinese Spring”. The results are as follows:P deficiency but not any other elements, is strongly increased the expressions of TaIPS1 genes in roots, while it is moderately increased the expressions of two TaIPS2 genes in roots and TaIPS1.1 in shoots, and is slightly increased the expressions of TaIPS1.2 and the two TaIPS2 genes in shoots. N deficiency completely repressed the responses of the three TaIPS1 genes to P deficiency in both roots and shoots, but had no significant influence on the expressions of the two TaIPS2 genes, suggesting that responses of some TaIPS genes to P deficiency depends on N status in wheat plants. It is interesting that TaIPS1.3 was induced by P deficiency in roots, but unexpectedly became compositive expression in lesves or shoot. Divided root experiment showed that TaIPS1 were mainly regulated by local signal instead of systemic signal of plant. The lower local Pi concentration is, the stronger expression of TaIPS1 is.“Xiaoyan54”is a high-afficient phosphate genotype wheat, while“Jing411”is a low-afficient phosphate genotype wheat.“Xiaoyan54”displayed higher phosphate efficiency更多还原