生长素促进拟南芥AtNRT1.1基因表达增强硝酸盐吸收

Auxin promotes nitrate uptake by up-regulating AtNRT1.1gene transcript level in Arobidopsis thaliana

为研究生长素信号对植物硝酸盐营养吸收的调控作用,采用扫描离子选择电极技术(SIET)和实时荧光定量PCR技术(qRT-PCR),测定拟南芥野生型Col-0、生长素过表达突变体yuc1-D以及生长素通路缺失突变体axr1-123种株系初始根中硝酸根离子(NO-3)吸收速率以及硝酸盐转运蛋白基因AtNRT1.1表达量的差异,并进一步检测Col-0株系以及硝酸盐转运蛋白突变体nrt1.1株系在正常条件(CK)或施加外源IAA及生长素极性运输抑制剂2,3,5-三碘苯甲酸(TIBA)处理下的NO-3流速和AtNRT1.1基因表达量的差异。结果表明:yuc1-D株系的NO-3吸收速率以及AtNRT1.1基因表达量相比野生型均有大幅增加,而axr1-12株系的NO-3吸收速率以及AtNRT1.1基因表达量相比野生型显著降低;在Col-0株系中施加外源IAA对NO-3吸收速率以及AtNRT1.1基因表达量有明显促进作用,而施加TIBA的效果反之,说明生长素对硝酸盐吸收有增强效应。nrt1.1株系在CK、IAA、TIBA处理下NO-3吸收速率差异较野生型不明显,揭示了AtNRT1.1基因在生长素促进硝酸盐吸收途径中所起的重要作用。

In order to study the mechanisms of the effects of auxin signaling pathway on nitrate uptake, scanning ion-selective electrode technique（SIET） and quantitative real-time PCR technique were used to determine net plasma membrane NO/ fluxes and the expression of nitrate transporter AtNRT1.1 in primary roots of Arabidopsis thaliana wild type Col-0, auxin overproducing mutant yucl-D, and auxin insensitive mutant axrl-12. Moreover, we examined net plasma membrane NO/ fluxes and the expression of AtNRT1.1 in primary roots of Col-0 and dual-affinity nitrate transporter mutant nrtl. 1 seedlings under the normal condition （CK）, the treatment with exogenous IAA or the treatment with the auxin efflux inhibitor 2.3.5-triidobenzoid acid （TIBA）. The nitrate uptake and AtNRT1. 1 gene transcript level in yucl-D seedlings were remarkably enhanced, whereas those in axrl-12 seedlings declined compared with Col-O seedlings. The exogenous IAA treatment enhanced nitrate uptake and AtNRT1. 1 gene transcript level in Col-O seedlings, while the TIBA treatment had an opposite effect. Furthermore, the differences of nitrate uptake and AtNRT1. 1 gene transcript level in nrtl. 1 seedlings among CK, IAA and TIBA treatments were insignificant compared with Col-0 seedlings, revealing the important role that AtNRT1. 1 gene played in nitrate uptake pathway response to auxin.