Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2007 Dec;145(4):1521-32.
doi: 10.1104/pp.107.106146. Epub 2007 Oct 19.

Differential expression of the TFIIIA regulatory pathway in response to salt stress between Medicago truncatula genotypes

Laura de Lorenzo  1 , Francisco Merchan, Sandrine Blanchet, Manuel Megías, Florian Frugier, Martin Crespi, Carolina Sousa
Affiliations

Differential expression of the TFIIIA regulatory pathway in response to salt stress between Medicago truncatula genotypes

Laura de Lorenzo et al. Plant Physiol. 2007 Dec.

Abstract

Soil salinity is one of the most significant abiotic stresses for crop plants, including legumes. These plants can establish root symbioses with nitrogen-fixing soil bacteria and are able to grow in nitrogen-poor soils. Medicago truncatula varieties show diverse adaptive responses to environmental conditions, such as saline soils. We have compared the differential root growth of two genotypes of M. truncatula (108-R and Jemalong A17) in response to salt stress. Jemalong A17 is more tolerant to salt stress than 108-R, regarding both root and nodulation responses independently of the nitrogen status of the media. A dedicated macroarray containing 384 genes linked to stress responses was used to compare root gene expression during salt stress in these genotypes. Several genes potentially associated with the contrasting cellular responses of these plants to salt stress were identified as expressed in the more tolerant genotype even in the absence of stress. Among them, a homolog of the abiotic stress-related COLD-REGULATEDA1 gene and a TFIIIA-related transcription factor (TF), MtZpt2-1, known to regulate the former gene. Two MtZpt2 TFs (MtZpt2-1 and MtZpt2-2) were found in Jemalong A17 plants and showed increased expression in roots when compared to 108-R. Overexpression of these TFs in the sensitive genotype 108-R, but not in Jemalong A17, led to increased root growth under salt stress, suggesting a role for this pathway in the adaptive response to salt stress of these M. truncatula genotypes.

PubMed Disclaimer

Figures

Figure 1.
Figure 1.
Effect of NaCl on root growth and dry weight of two M. truncatula genotypes. Root length and dry weight biomass under different salt stress conditions were evaluated in an in vitro system. Germinated seedlings were grown on vertical Fahräeus or “i” medium plates for 5 d in the presence of different NaCl concentrations (0, 30, 60, 90, 120, and 150 mm). A, Relative root length of each variety at 5 d.a.g. in in vitro conditions with Fahräeus medium is shown as percentage of control root growth without salt. B, Representative pictures taken 5 d after transfer of the seedlings to 0, 30, and 120 mm NaCl on Fahräeus medium. C, Relative dry weights of roots and leaves from M. truncatula 108-R and Jemalong A17 after 15 d of growth in Fahräeus medium submitted to different salt stress treatments. Results are shown as percentage of control without salt. Ratio (right) represents root dry weight/leaf dry weight to evaluate the effect of salinity on dry weight biomass of the plants. D, Relative root growth (%) of the two M. truncatula varieties grown under nonstressed and salt-stressed conditions in “i” medium for 5 d. Values indicated with different letters indicate statistically significant differences (P < 0.01), whereas those marked with the same letters show statistically similar values. IC, Interval of confidence (α = 0.01). Columns labeled with an asterisk are significantly different (P < 0.01) within a given salinity level. In both cases, the Kruskal and Wallis test has been used. A representative example out of two biological experiments is shown.
Figure 2.
Figure 2.
Effect of salt stress on nodulation in M. truncatula 108-R and Jemalong A17. Seeds of the two genotypes were germinated on water agar plates, and seedlings were grown in the greenhouse in the presence of different NaCl concentrations (0, 30, 60, 90, 120, and 150 mm). The inoculation with S. meliloti strain 2011 was made 9 d.a.g.. Nodule number and root and leaf dry weights were determined at 30 d.a.g. (21 d.p.i.). A, The effect of salt concentration on nodulation of M. truncatula 108-R and Jemalong A17 by S. meliloti strain 2011 is measured as percentage of the total nodule number 21 d.p.i. observed in control (without salt) conditions. B, Relative dry weights (%) of root system and aerial part of M. truncatula 108-R and Jemalong A17 genotypes at 30 d.a.g. under different salt stress conditions. IC, Interval of confidence (α = 0.05). Columns labeled with an asterisk are significant differences (P < 0.05) between genotypes within a given salinity level. Statistical comparisons were performed using the Kruskal and Wallis test. A representative example out of two biological experiments is shown.
Figure 3.
Figure 3.
Gene expression profiles of M. truncatula 108-R and Jemalong A17. A, Experimental design is based on series of pairwise comparisons. Four d.a.g. seedlings from different genotypes (R for 108-R and J for Jemalong A17) were grown for 4 d without (0 mm; R0 and J0) or with (R4 and J4) 150 mm NaCl. Two biological and four technical replicates were available for each gene, for each physiological condition, and for each genotype. B, The histogram shows the total number of transcripts up- or down-regulated in 108-R (left bars) and Jemalong A17 (right bars) in response to salinity stress at a level of P < 0.01. C, Venn diagrams illustrating the number of genes up-regulated or down-regulated under salinity stress in either or both genotypes of M. truncatula (108-R, left, and Jemalong A17, right). D, Distribution of differentially expressed genes into functional categories according to BLASTN hits (based on Journet et al., 2002; Merchan et al., 2007). Percentages were calculated from the total number of differentially expressed genes from Jemalong A17 (112 genes).
Figure 4.
Figure 4.
Real-time RT-PCR analysis of selected genes differentially expressed between genotypes in response to salt stress. Specific gene expression in the salt-tolerant (Jemalong A17) versus salt-sensitive (108-R) genotypes were analyzed in control and salt stress conditions (4 d at 150 mm NaCl). Induction ratios were calculated between the salt-treated and nontreated samples. A representative example out of two biological experiments is shown, and error bars represent sd of three technical replicates. Numbers on the x axis indicate the fold-induction of gene expression in relation to the nonsalt stress condition. A, Real-time RT-PCR of five randomly selected differentially expressed genes between genotypes: MtHP2, a His-containing phosphotransfer protein homolog gene (a gene involved in cytokinin signal transduction); MtCorA1, a cold-and drought-regulated CORA protein homolog gene; MtADPr, a gene encoding an ADP-ribosylation factor homolog protein; MtDor, a gene coding for a dormancy-associated protein; and MtDehyd, a gene encoding a dehydrin-related protein. B, Real-time RT-PCR analysis of two genes that encode putative TFIIIA-type TFs (MtZpt2-1 and MtZpt2-2).
Figure 5.
Figure 5.
Evaluation of root growth in A. rhizogenes-transformed M. truncatula roots overexpressing MtZpt2-1 or MtZpt2-2. Composite plants were prepared as described in Boisson-Dernier et al. (2001) using control empty vector and MtZpt2-1 or MtZpt2-2 overexpressing constructs. After kanamycin selection of transgenic roots, composite plants were transferred to salt-containing or control media. A representative example out of two biological experiments is shown in all cases. *, Statistically significant differences (P < 0.01; n > 25). A and B, Growth of transgenic roots overexpressing either MtZpt2-1 or MtZpt2-2 in M. truncatula 108-R was monitored 1 week after transfer into control (A) or a salt-containing medium (100 mm NaCl; B). The initial position of the root apex after transfer was monitored to determine the degree of root elongation during the week. C and D, Idem as A and B for Jemalong A17 indicating transgenic root growth in control (C) or salt-containing medium (100 mm NaCl; D).
See this image and copyright information in PMC

Similar articles

See all similar articles

Cited by

See all "Cited by" articles

References

    1. Apse MP, Aharon GS, Snedden WA, Blumwald E (1999) Salt tolerance conferred by overexpression of a vacuolar Na+/H+ antiport in Arabidopsis. Science 285 1256–1258 - PubMed
    1. Arrese-Igor C, González E, Gordon A, Minchin F, Gálvez L, Royuela M, Cabrerizo P, Aparicio-Tejo P (1999) Sucrose synthase and nodule nitrogen fixation under drought and environmental stresses. Symbiosis 27 189–212
    1. Assmann S, Wang X (2001) From milliseconds to millions of years: guard cells and environmental responses. Plant Biol 4 421–428 - PubMed
    1. Austin RB (1993) Augmenting yield-based selection. In MD Hayward, I Romagosa, eds, Plant Breeding Principles and Prospects. Chapman and Hall, London, pp 391–405
    1. Barker DG, Bianchi S, Blondon F, Dattée Y, Duc G, Essad S, Flament P, Gallusci P, Génier G, Guy P, et al (1990) Medicago truncatula, a model plant for studying the molecular genetics of the Rhizobium-legume symbiosis. Plant Mol Biol Rep 8 40–49

Publication types

MeSH terms

Substances

LinkOut - more resources

  NODES
twitter 2