Article

Identification of transcription factors involved in root apex responses to salt stress in Medicago truncatula. Mol Genet Genom

Institut des Sciences du Végétal, C.N.R.S., 91198, Gif-sur-Yvette, France.
Molecular Genetics and Genomics (Impact Factor: 2.73). 12/2008; 281(1):55-66. DOI: 10.1007/s00438-008-0392-8
Source: PubMed

ABSTRACT

The root apex contains meristematic cells that determine root growth and architecture in the soil. Specific transcription factor (TF) genes in this region may integrate endogenous signals and external cues to achieve this. Early changes in transcriptional responses involving TF genes after a salt stress in Medicago truncatula (Mt) roots were analysed using two complementary transcriptomic approaches. Forty-six salt-regulated TF genes were identified using massive quantitative real-time RT-PCR TF profiling in whole roots. In parallel, Mt16K+ microarray analysis revealed 824 genes (including 84 TF sequences) showing significant changes (p < 0.001) in their expression in root apexes after a salt stress. Analysis of salt-stress regulation in root apexes versus whole roots showed that several TF genes have more than 30-fold expression differences including specific members of AP2/EREBP, HD-ZIP, and MYB TF families. Several salt-induced TF genes also respond to other abiotic stresses as osmotic stress, cold and heat, suggesting that they participate in a general stress response. Our work suggests that spatial differences of TF gene regulation by environmental stresses in various root regions may be crucial for the adaptation of their growth to specific soil environments.

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    • "Many TFs have been reported to regulate the response to drought and salt stress in M. truncatula at the transcriptional level. Microarray Mt16K+ showed that the expression of WRKY TFs changed significantly in root apexes under 100 mM NaCl stress (Gruber et al., 2009). MtNAC969 was induced by abiotic stresses (salt, drought and cold), and shown to increase the tolerance to high salinity (de Zelicourt et al., 2012). "
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    • "In a parallel study, transcriptome analysis based on the 16K+ microarrays (Mt16KOLI1) using salttreated root apexes was performed in the model legume M. truncatula (Gruber et al., 2009) comparing the salt tolerant TN1.11 variety and the reference Jemalong A17 genotype. The hormonal response to salt stress of M. truncatula roots was monitored in different tissues (roots, stem and leaves) at different time point from stress onset. "
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    • "M. truncatula is also an interesting model for analysing responses to salt stress. These responses have been studied at different levels from whole-plant to molecular analysis (Veatch et al. 2004; López et al. 2008a, 2008b de Lorenzo et al. 2009; Li et al. 2009 Li et al. , 2011 Merchan et al. 2007; Ariel et al. 2010; Gruber et al. 2009; Arraouadi et al. 2011 Arraouadi et al. , 2012) and several genes that are putatively involved in different mechanisms of tolerance to salt stress have been reported (Gruber et al. 2009; Zahaf et al. 2012). In addition, the natural diversity of M. truncatula with respect to salt stress has been characterised. "
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