Expression of Genes Involved In Drought Tolerance In Response to Osmotic Shock In Six Genotypes of Cotton Roots

Water availability is one of the major limitations to plant productivity (Boyer, 1982). In Cotton (Gossypium hirsutum L.) yield stability and fiber quality of cotton can be reduced as a result of drought stress (Hendrix, 2006). Cotton plants respond and adapt to drought stress in order to survive. This stress induces various biochemical and physiological responses. Several genes that respond to this stress at the transcriptional level have been studied. Stress-inducible genes have been used to improve the stress tolerance of plants by gene transfer. It is important to analyze the functions of stress- inducible genes not only to understand the molecular mechanisms of stress tolerance and the responses of higher plants but also to improve the stress tolerance of crops by gene manipulation (Jenks & Hasegawa, 2005). The objective of this study was to identify the expression in 14 genes previously identified as drought-tolerance genes in Arabidopsis thaliana L., this species can serve as a drought-tolerance model for engineering candidate gene in crop plants, in six genotypes of cotton. These 14 genes had been found to be involved in abscisic acid (ABA)-related stress signaling. Zhang et al. (2008) identified SDIR1-over-expressing Arabidopsis plants exhibit improved tolerance to drought. The species used for the development of this study (ST4554, VH260, AD3 JFZ15, DP33B G101, AD1 LMK-4, DP491) were grown in hydroponic culture for 30 days under 1x Hoagland solution. The solution was changed to 8% polyethylene-glycol plus 0.25x Hoagland solution or 0.25x Hoagland solution alone in order to induce osmotic shock. The plants were harvested at 12 and 24 hours after treatment application and gene expression was assayed using real-time PCR.