氮磷亏缺对小麦TaIPS基因表达的影响

为了解小麦高效利用土壤磷的分子机理和实现对小麦缺磷的分子诊断,以普通小麦(Triticum aestivum L.)小偃54为材料,克隆了5个受缺磷诱导的IPS基因,同源比较结果显示,小麦IPS基因属于典型的受缺磷条件特异诱导的TPSI1/MT4小基因家族.对小麦根系和地上部的半定量RT-PCR研究结果表明,与全营养处理对照相比,3叶期小麦幼苗经过缺氮、缺磷和氮磷同时缺乏处理8d后,缺磷显著增加了根系中3个TaIPS1(TaIPS1.1、TaIPS1.2和TaIPS1.3)基因和地上部TaIPS1.1基因的表达,中度上调了根系中2个TaIPS2基因(TaIPS2.1和TaIPS2.2)的表达,轻度上调了地上部TaIPS1.2和2个TaIPS2基因的表达.通过比较5个基因在根系和地上部对缺磷的响应,认为TaIPS1.1是一个较理想的用于诊断小麦植株磷素丰缺的基因.缺氮不仅降低了3个TaIPS1基因在根系中的表达,并抑制了IPS基因对缺磷的响应.这一研究结果预示了TaIPS基因对低磷胁迫的响应依赖于植株体内的氮素营养状况.

Expression of TaIPS Genes in Wheat Seedlings with Nitrogen and Phosphorus Starvation

In order to establish a molecular technique for diagnosing phosphorus status of wheat plant and to study the adaptive mechanisms for wheat to Pi deficiency,in the present study five IPS(induced by phosphate starvation) genes were cloned from wheat.They are three TaIPS1 genes (TaIPS1.1,TaIPS1.2 and TaIPS1.3) and two TaIPS2 genes (TaIPS2.1 and TaIPS2.2).The five IPS genes belong to the TPSI1/MT4 small gene family which are specifically induced by phosphate starvation in dicot and monocot plant species.Expressions of these five genes in roots and shoots of wheat seedlings deprived of nitrogen,phosphorus or both nitrogen and phosphorus for eight days were investigated using semi-quantitative RT-PCR.The results showed that phosphorus starvation strongly increased the expression levels of the three TaIPS1 genes in roots and TaIPS1.1 in shoots,moderately increased the expression levles of the two TaIPS2 genes in roots,and slightly increased the expressions of TaIPS1.2 and the two TaIPS2 genes in shoots.These results indicated that TaIPS1.1 is suitable for diagnosing phosphorus status of wheat plant.Nitrogen deficiency strongly repressed the mRNA levels of the three TaIPS1 genes in roots,and inhibited the responses of IPS gene to Pi deficiency,suggesting that responses of IPS gene to Pi deficiency depends on the nitrogen status of plants.