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


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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    • "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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    ABSTRACT: Oxylipin family of signals represents one of the mechanisms employed by plants to communicate and respond to wounding, herbivores, and to biotic and abiotic stresses. This family comprises fatty acid hydroperoxides, hydroxy-, keto- or oxo- fatty acids, volatile aldehydes, divinyl ethers and Jasmonic Acid (JA). Most of them are volatile compounds participating in several physiological processes, defence mechanism, stress adaptation and communication with other plants and microorganisms. Studies on the comparison of jasmonates, OPDA, and Abscisic Acid (ABA) content and of gene expression variation in chickpea roots from a drought tolerant and a responsive variety, have confirmed preliminary studies made on drought and salt stress on different chickpea varieties, showing that involvement and up-regulation of specific LOX, AOS and HPL isoforms is required for stress tolerance. In this context, various levels of regulation of jasmonate signaling and JA biosynthesis pathway are discussed, sustained by observations made in roots and nodules of salt stressed chickpea varieties. Finally, an additional level of regulation of JA by epigenetics and microRNAs, with the involvement of ABA and NO responsive elements in promoters of transcription factor genes, is briefly introduced. Here we report about new insights on the role of the differential activation of JA biosynthesis during abiotic stress in roots of varieties differently responding to drought and salt stress, and on the importance of earlier and stronger JA induction as a trait conferring better drought tolerant in legume varieties able to cope with water stress. Real-time PCR may be useful to evaluate the timing and expression levels of specific gene isoforms in tolerant varieties, thus supporting breeding programmes for the identification of hybrids with improved JA synthesis, able to activate oxylipin specific pathways in a sustained and prolonged time course after stress perception.
    Abiotic stresses in crop plants., Edited by Chakraborty U., Chakraborty B.N., 09/2014: chapter Monitoring the activation of jasmonate biosynthesis genes for selection of chickpea hybrids tolerant to drought stress.; CABI International.
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    • "Microarrays have been extensively used to generate transcriptional profiles in response to abiotic stresses in a range of plant species including, but not limited to, Arabidopsis (Kreps et al., 2002), Vitis vinifera L. (grapevine; Cramer et al., 2007) and Hordeum vulgare L. (barley; Walia et al., 2006). Studies of the transcriptional response to salt stress have been conducted in barley (Ueda et al., 2004, 2006; Walia et al., 2006, 2007; Gruber et al., 2009) and the model cereal Brachypodium (Kim et al., 2012) but due to the polyploidy genome, studies of wheat are more limited (Kawaura et al., 2006, 2008; Mott and Wang, 2007; Jamil et al., 2011; Garg et al., 2013).As the technology of microarrays and cell separation techniques has become more advanced it has become possible to do spatial profiling of plant tissues and cell-specific studies (Brady et al., 2007; Dinneny et al., 2008; Spollen et al., 2008). Cell-type specific transcript studies have been conducted in many plant species including Arabidopsis and the cereals maize, rice, barley, and soybean using microarrays (Pu and Brady, 2010; Long, 2011; Rogers et al., 2012). "
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    ABSTRACT: Abiotic stresses such as low water availability and high salinity are major causes of cereal crop yield losses and significantly impact on sustainability. Wheat and barley are two of the most important cereal crops (after maize and rice) and are grown in increasingly hostile environments with soil salinity and drought both expected to increase this century, reducing the availability of arable land. Barley and wheat are classified as glycophytes (salt-sensitive), yet they are more salt-tolerant than other cereal crops such as rice and so are good models for studying salt tolerance in cereals. The exploitation of genetic variation of phenotypic traits through plant breeding could significantly improve growth of cereals in salinity-affected regions, thus leading to improved crop yields. Genetic variation in phenotypic traits for abiotic stress tolerance have been identified in land races and wild germplasm but the molecular basis of these differences is often difficult to determine due to the complex genetic nature of these species. High-throughput functional genomics technologies, such as transcriptomics, metabolomics, proteomics, and ionomics are powerful tools for investigating the molecular responses of plants to abiotic stress. The advancement of these technologies has allowed for the identification and quantification of transcript/metabolites in specific cell types and/or tissues. Using these new technologies on plants will provide a powerful tool to uncovering genetic traits in more complex species such as wheat and barley and provide novel insights into the molecular mechanisms of salinity stress tolerance.
    Frontiers in Plant Science 05/2013; 4:123. DOI:10.3389/fpls.2013.00123 · 3.95 Impact Factor
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    • "Some compounds, such as proline betaine, trehalose, trigonelline, and a pyridine betaine, have been reported to play a role in the response to salt stress of different legumes. Furthermore, proline accumulation has been shown to enhance SNF during salt stress in M. truncatula (Gruber et al., 2009). In a recent functional analysis, a general increase in the steady-state level of many amino acids, sugars, and polyols, with a concurrent decrease in most organic acids in response to gradual salt stress in L. japonicus leaves. "
    Faba Bean (Vicia faba L) An Potential legume for India, Ist edited by A K Singh, BP Bhatt, 04/2013: chapter Status of biotechnological approach to improve faba bean (Vicia faba L.) Seed yield and quality: pages 141-154; ICAR, RC for ER, Patna., ISBN: 978-93-5067-773-5
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