Article

Identification of transcription factors involved in root apex responses to salt stress in Medicago truncatula

Institut des Sciences du Végétal, C.N.R.S., 91198, Gif-sur-Yvette, France.
Molecular Genetics and Genomics (Impact Factor: 2.83). 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.

Electronic supplementary material
The online version of this article (doi:10.1007/s00438-008-0392-8) contains supplementary material, which is available to authorized users.

Download full-text

Full-text

Available from: Adnane Boualem, Jun 30, 2015
2 Followers
 · 
289 Views
  • Source
    [Show abstract] [Hide abstract]
    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.
  • Source
    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
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The root system is crucial for the acquisition of resources from the soil. In legumes, the efficiency of mineral and water uptake by the roots may be reinforced due to the establishment of symbiotic relationships with mycorrhizal fungi and interactions with soil rhizobia. Here, we investigated the role of miR396 in regulating the architecture of the root system and in symbiotic interactions in the model legume Medicago truncatula. Promoter-GUS analyses suggested that the two mtr-miR396a and miR396b genes are highly expressed in root tips, preferentially in the transition zone, and display distinct expression profiles during lateral root and nodule development. Transgenic roots of composite plants that overexpress the miR396b precursor showed lower expression of 6 Growth Regulating Factors (MtGRF) and 2 bHLH79-like targets as well as reduced growth and mycorrhizal associations. In contrast, miR396 inactivation by mimicry caused contrasting tendencies, with increased target expression, higher root biomass and a more efficient colonisation by AM fungi. In contrast to MtbHLH79, repression of three different GRF targets by RNA interference severely impaired root growth. Early activation of mtr-miR396b, concomitant with a post-transcriptional repression of MtGRF5 expression, was also observed in response to exogenous brassinosteroids. Growth limitation in miR396-OE roots correlated with a reduction of cell-cycle gene expression and the number of dividing cells in the root apical meristem. These results link the miR396 network to the regulation of root growth and mycorrhizal associations in plants. This article is protected by copyright. All rights reserved.
    The Plant Journal 04/2013; DOI:10.1111/tpj.12178 · 6.82 Impact Factor