Abstract
Our containment trials have established cold tolerance in Nicotiana tabacum osmotin (Nt Osm) transgenic tomato (Solanum lycopersicum L. cv. Pusa Ruby). Though, the stress tolerance mechanisms have been studied at physio-biochemical levels, molecular mechanisms underlying the tolerant response are still not well studied. Therefore, quantitative transcript expression of Osmotin and other stress responsive genes (CBF1, P5CS and APX) was studied in response to cold (4°C; 2 and 24 h) treatment in the transgenic and wild type tomato plants. The expression analysis revealed differential transcript regulation in the transgenic and wild type plants on the cold exposure. In general, the genes were either earlier induced or the extent of fold change in transcript expression over the respective untreated controls was higher in transgenic than in the wild type plants on cold exposure. The transcript expression data also supported the metabolite analysis on free Proline and ascorbate content. The results thus suggest that constitutive over expression of the Osmotin modulate transcript abundance and functional expression products of the other stress responsive genes thereby, imparting cold tolerance in the transgenic tomato plants.Electronic supplementary materialThe online version of this article (doi:10.1186/2193-1801-2-117) contains supplementary material, which is available to authorized users.
Highlights
Osmotin or Osmotin-like proteins have been shown to be accumulated in response to various biotic and abiotic stresses in plants
In the present study, transcript expression of the genes involved in various functions including transcript regulation (CBF1) osmotic adjustment (P5CS), and antioxidant defence (APX) along with Osmotin was analyzed using qRT PCR to understand the molecular mechanisms of cold tolerance in the transgenic tomato
The transcript expression of the selected stress responsive genes was differentially regulated in the Osmotin transgenic and wild type tomato plants on short and relatively long term cold exposure (Table 1)
Summary
Osmotin or Osmotin-like proteins have been shown to be accumulated in response to various biotic and abiotic stresses in plants. Over-expression of the gene in transgenic plants is known to impart tolerance against various biotic and abiotic stresses including cold, salt and drought (Goyary 2009; Parkhi et al 2009; Goel et al 2010; Das et al 2011; Subramanyan et al 2011). There are some reports on the possible mechanism underlying the defense function of Osmotin against biotic stresses, its role in abiotic stress response is still unclear. Our laboratory has developed Osmotintransgenic tomato using Agrobacterium mediated genetic transformation and advanced desired line to T8 generation to enhance cold tolerance. Containment evaluation trials at Defence Institute of High Altitude Research (DIHAR), Leh (11,500’ asl), India and Defence Information on regulation of genes involved in various stress response pathways is not available in Osmotin transgenic tomato and other plants
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