Regulation by ABA of osmotic‐stress‐induced changes in protein synthesis in tomato roots

Abstract

Polypeptide synthesis and accumulation were examined in the roots of tomato seedlings exposed to a polyethylene glycol-imposed water deficit stress. In these roots, the synthesis of a number of polypeptides was induced, while that of several others was enhanced or repressed. To examine the role played by abscisic acid (ABA) in co-ordinating the accumulation of these proteins, water-deficit-stressresponsive polypeptide synthesis was investigated in the roots of the ABA-deficient mutant flacca. In the roots of this mutant, the ability to accumulate a complete set of water-deficit-stress-responsive polypeptides was impaired, indicating that ABA is required for their synthesis. The role of ABA was further examined by exposing the roots of both genotypes to exogenous ABA, which, with one exception, elicited the accumulation of all water-deficit-stressresponsive proteins. Polyethylene glycol-induced polypeptide accumulation was accompanied by a 1·6-fold increase in the level of endogenous ABA in the roots of wild-type plants and a 5-fold increase in the roots of flc. Thus, although the absolute level was lower than that of the wildtype, flc has the capacity to accumulate ABA in its roots. When fluridone was used to prevent the biosynthesis of ABA, the accumulation of several water-deficit-stressresponsive polypeptides was reduced further. The synthesis of polypeptides was also examined in the roots of salttreated seedlings. Salt altered the accumulation of several polypeptides, all of which were previously observed in water-deficit-stressed roots, indicating that their synthesis was the result of the osmotic component of the salt stress. However, the accumulation of these polypeptides was not impaired in flc roots, indicating that the role played by ABA in regulating their accumulation in salt-and polyethylene glycol-treated roots differs. As such, salt-and waterdeficit-stress-induced changes in gene expression may be effected by different mechanisms, at least at the level of polypeptide accumulation.

Proteomic analysis of nuclear proteins during dehydration of the resurrection plant Xerophyta viscosa

“…Relative water content was determined for leaf samples and was calculated using the method described previously (Henson et al 1981;Jiang et al 2007;Jin et al 2000): RWC (%) = [(FW -DW)/(TW -DW)] 9 100.…”

Growth and Transpiration of Tomato Seedlings Grown in Hazelnut Husk Compost Under Water-Deficit Stress

“…But, there were no statistical differences among the water stress levels. Jin et al (2000) reported that osmotic-stress has an impact on growth of both the shoot and the roots of tomato; however, growth of the shoot is affected to a greater extent than that of the roots. Xu et al (2006) explained that water stress significantly improved R/S ratio of seedlings.…”

A novel stress-inducible antioxidant enzyme identified from the resurrection plant Xerophyta viscosa Baker

“…The weight at full turgor (W t ) was taken and leaf samples were then dried at 95°C for 24 h and the dry weight (W d ) was recorded. The RWC was calculated using the formula previously determined by Jin et al (2000):…”