Merchan Francisco, de Lorenzo Laura, Rizzo Silvina González, Niebel Andreas, Manyani Hamid, Frugier Florian, Sousa Carolina, Crespi Martin
Departamento de Microbiología y Parasitología, Universidad de Sevilla, 41012 Sevilla, España.
Plant J. 2007 Jul;51(1):1-17. doi: 10.1111/j.1365-313X.2007.03117.x. Epub 2007 May 3.
Root growth and function are determined by the action of environmental stresses through specific genes that adapt root development to these restrictive conditions. We have defined in vitro conditions affecting the growth and recovery of Medicago truncatula roots after a salt stress. A dedicated macroarray containing 384 genes, based on a large-scale subtractive hybridization approach, was constructed and used to analyze gene expression during salt stress and recovery of root growth from this stress. Several potential regulatory genes were identified as being linked to this recovery process: a novel RNA-binding protein, a small G-protein homologous to ROP9, a receptor-like kinase, two TF IIIA-like and an AP2-like transcription factors (TF), MtZpt2-1, MtZpt2-2 and MtAp2, and a histidine kinase associated with cytokinin transduction pathways. The two ZPT2-type TFs were also rapidly induced by cold stress in roots. By analyzing transgenic M. truncatula plants showing reduced expression levels of both TFs and affected in their capacity to recover root growth after a salt stress, we identified potential target genes that were either activated or repressed in these plants. Overexpression of MtZpt2-1 in roots conferred salt tolerance and affected the expression of three putative targets in the predicted manner: a cold-regulated A (CORA) homolog, a flower-promoting factor (FPF1) homolog and an auxin-induced proline-rich protein (PRP) gene. Hence, regulatory networks depending on TFIIIA-like transcription factors are involved in the control of root adaptation to salt stress.
根系的生长和功能是由环境胁迫通过特定基因的作用所决定的，这些基因使根系发育适应这些限制性条件。我们已经确定了影响盐胁迫后蒺藜苜蓿根系生长和恢复的体外条件。基于大规模消减杂交方法构建了一个包含384个基因的专用基因芯片，并用于分析盐胁迫期间以及从该胁迫中恢复根系生长过程中的基因表达。鉴定出了几个与该恢复过程相关的潜在调控基因：一种新型RNA结合蛋白、一种与ROP9同源的小G蛋白、一种类受体激酶、两种类TFIIIA和一种AP2类转录因子（TF），即MtZpt2-1、MtZpt2-2和MtAp2，以及一种与细胞分裂素转导途径相关的组氨酸激酶。这两种ZPT2型TFs在根中也会被冷胁迫快速诱导。通过分析转基因蒺藜苜蓿植株，这些植株显示出两种TFs的表达水平降低且在盐胁迫后恢复根系生长的能力受到影响，我们确定了在这些植株中被激活或抑制的潜在靶基因。在根中过表达MtZpt2-1赋予了耐盐性，并以预测的方式影响了三个假定靶标的表达：一个冷调节A（CORA）同源物、一个促进开花因子（FPF1）同源物和一个生长素诱导的富含脯氨酸蛋白（PRP）基因。因此，依赖于类TFIIIA转录因子的调控网络参与了根系对盐胁迫适应性的控制。
