Overexpression. of dehydrin tas14 gene improves the osmotic stress imposed by drought and salinity in tomato

CEBAS-CSIC, Department of Stress Biology and Plant Pathology, Campus de Espinardo, P.O. Box 164, 30100 Espinardo-Murcia, Spain.
Journal of plant physiology (Impact Factor: 2.56). 03/2012; 169(5):459-68. DOI: 10.1016/j.jplph.2011.11.018
Source: PubMed


One strategy to increase the level of drought and salinity tolerance is the transfer of genes codifying different types of proteins functionally related to macromolecules protection, such as group 2 of late embryogenesis abundant (LEA) proteins or dehydrins. The TAS14 dehydrin was isolated and characterized in tomato and its expression was induced by osmotic stress (NaCl and mannitol) and abscisic acid (ABA) [Godoy et al., Plant Mol Biol 1994;26:1921-1934], yet its function in drought and salinity tolerance of tomato remains elusive. In this study, transgenic tomato plants overexpressing tas14 gene under the control of the 35SCaMV promoter were generated to assess the function of tas14 gene in drought and salinity tolerance. The plants overexpressing tas14 gene achieved improved long-term drought and salinity tolerance without affecting plant growth under non-stress conditions. A mechanism of osmotic stress tolerance via osmotic potential reduction and solutes accumulation, such as sugars and K(+) is operating in tas14 overexpressing plants in drought conditions. A similar mechanism of osmotic stress tolerance was observed under salinity. Moreover, the overexpression of tas14 gene increased Na(+) accumulation only in adult leaves, whereas in young leaves, the accumulated solutes were K(+) and sugars, suggesting that plants overexpressing tas14 gene are able to distribute the Na(+) accumulation between young and adult leaves over a prolonged period in stressful conditions. Measurement of ABA showed that the action mechanism of tas14 gene is associated with an earlier and greater accumulation of ABA in leaves during short-term periods. A good feature for the application of this gene in improving drought and salt stress tolerance is the fact that its constitutive expression does not affect plant growth under non-stress conditions, and tolerance induced by overexpression of tas14 gene was observed at the different stress degrees applied to the long term.

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    • "In this group, many potato genes showed high homology to the well-known abiotic stress-inducible genes, such as proteinase inhibitor type II (Pi7c) (Huang et al. 2007), TaS14 (Munoz Mayor et al. 2012), and stress-associated protein 3 (Solanke et al. 2009) (Table 1). For instance, TAS14 over expressed tomato plants showed increased drought and salinity stress tolerance compared with wild-type plants (Munoz Mayor et al. 2012). Taking into account, improved thermo-tolerance exhibited by transgenic yeast cells expressing TAS14 provides first insights that the activation and function of the TAS14 gene may be crucial for growing potato plants under heat stress (Supplementary Table 4). "
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    ABSTRACT: Potato (S. tuberosum) is a highly heat-sensitive crop; a slight rise from optimal temperature can lead to drastic decline in tuber yield. Despite several advancements made in breeding for thermo-tolerant potato, molecular mechanisms governing thermo-tolerance is poorly understood. The first step towards understanding the thermo-tolerance mechanism is to identify the key genes involved in it. Here we used a yeast-based functional screening method to identify, characterize and classify potato genes with potentials to impart heat tolerance. We constructed two cDNA expression libraries from heat-stressed potato plants (35 °C) after 2 and 48 h of treatment. 95 potential candidate genes were identified based on enhanced ability of yeast cells over-expressing heterologous potato cDNA sequences to tolerate heat stress. Cross-resistance analysis of these heat-tolerant yeast clones to other abiotic stresses indicated that 20 genes were responsive to drought, 14 to salt and 11 to heat/drought/salt stresses. Comparison of 95 genes with reported whole potato transcriptome data showed that majority of them have varying expression patterns under heat, drought and salt stresses. The expression pattern was validated by analyzing the expression of 22 randomly selected genes under various stresses using qPCR. Gene ontology (GO) enrichment analysis of these 95 genes indicated that most of them are involved in various cellular metabolism, signal transduction, response to stress and protein folding, suggesting possible role of these genes in heat tolerance of potato. Genes identified from this study can be potential candidates for engineering heat tolerance as well as broad-spectrum abiotic stress tolerance of potato.
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    • "Overexpression of AtLEA3-3 in Arabidopsis confers salt and osmotic stress tolerance that is characterized during germination and early seedling establishment [9]. Muñoz-Mayor et al. [10] also identified that the plants overexpressing tas14 gene achieved improvement in long-term drought and salinity tolerance without affecting plant growth under non-stress conditions. "
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