Identification of regulatory pathways involved in the reacquisition of root growth after salt stress in Medicago truncatula.
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.
Merchan
Francisco
F
Departamento de Microbiología y Parasitología, Universidad de Sevilla, 41012 Sevilla, España.
de Lorenzo
Laura
L
Rizzo
Silvina González
SG
Niebel
Andreas
A
Manyani
Hamid
H
Frugier
Florian
F
Sousa
Carolina
C
Crespi
Martin
M
D000222:Adaptation, Physiological; D016375:Antisense Elements (Genetics); D003583:Cytokinins / Q000378:metabolism; D020869:Gene Expression Profiling; D018506:Gene Expression Regulation, Plant; D015723:Gene Library; D053263:Gene Regulatory Networks / Q000502:physiology; D017343:Genes, Plant; D046913:Medicago truncatula / Q000235:genetics* / Q000254:growth & development / Q000502:physiology; D018517:Plant Roots / Q000254:growth & development*; D015398:Signal Transduction / Q000502:physiology; D012965:Sodium Chloride / Q000378:metabolism*; D014157:Transcription Factors / Q000378:metabolism / Q000502:physiology; D015533:Transcriptional Activation
D016375:Antisense Elements (Genetics); D003583:Cytokinins; D014157:Transcription Factors; D012965:Sodium Chloride