Song W, Koh S, Czako M, Marton L, Drenkard E, Becker J M, Stacey G
Centre for Legume Research, University of Tennessee, Knoxville 37996-0845, USA.
Plant Physiol. 1997 Jul;114(3):927-35. doi: 10.1104/pp.114.3.927.
Previously, we identified a peptide transport gene, AtPTR2-B, from Arabidopsis thaliana that was constitutively expressed in all plant organs, suggesting an important physiological role in plant growth and development. To evaluate the function of this transporter, transgenic Arabidopsis plants were constructed expressing antisense or sense AtPTR2-B. Genomic Southern analysis indicated that four independent antisense and three independent sense AtPTR2-B transgenic lines were obtained, which was confirmed by analysis of the segregation of the kanamycin resistance gene carried on the T-DNA. RNA blot data showed that the endogenous AtPTR2-B mRNA levels were significantly reduced in transgenic leaves and flowers, but not in transgenic roots. Consistent with this reduction in endogenous AtPTR2-B mRNA levels, all four antisense lines and one sense line exhibited significant phenotypic changes, including late flowering and arrested seed development. These phenotypic changes could be explained by a defect in nitrogen nutrition due to the reduced peptide transport activity conferred by AtPTR2-B. These results suggest that AtPTR2-B may play a general role in plant nutrition. The AtPTR2-B gene was mapped to chromosome 2, which is closely linked to the restriction fragment length polymorphism marker m246.
此前，我们从拟南芥中鉴定出一个肽转运基因AtPTR2 - B，该基因在所有植物器官中组成型表达，表明其在植物生长发育中具有重要的生理作用。为了评估这种转运蛋白的功能，构建了表达反义或正义AtPTR2 - B的转基因拟南芥植株。基因组Southern分析表明，获得了四个独立的反义AtPTR2 - B转基因株系和三个独立的正义AtPTR2 - B转基因株系，通过对T - DNA上携带的卡那霉素抗性基因的分离分析得以证实。RNA印迹数据显示，转基因叶片和花中内源性AtPTR2 - B mRNA水平显著降低，但转基因根中未降低。与内源性AtPTR2 - B mRNA水平的这种降低一致，所有四个反义株系和一个正义株系都表现出显著的表型变化，包括开花延迟和种子发育停滞。这些表型变化可以通过AtPTR2 - B赋予的肽转运活性降低导致的氮营养缺陷来解释。这些结果表明AtPTR2 - B可能在植物营养中发挥普遍作用。AtPTR2 - B基因被定位到2号染色体上，它与限制性片段长度多态性标记m246紧密连锁。
