Over-expression of tobacco NtHSP70-1 contributes to drought-stress tolerance in plants

Abstract

HSP70, a heat shock protein, is a molecular chaperone responsive to various environmental stresses. Here, NtHSP70-1 was a drought-/ABA-inducible gene. We monitored the expression of CaERD15 (early responsive to dehydration) with exposing plants to progressive drought stress. Its activity was used as an indicator of water-deficit conditions. To analyze the protective role of HSP70, we obtained transgenic tobacco plants that constitutively expressed elevated levels of the tobacco HSP70, NtHSP70-1, as well as transgenic plants containing either the vector alone or else having NtHSP70-1 in the antisense orientation. Plants with enhanced levels of NtHSP70-1 in their transgenic sense lines exhibited tolerance to water stress. Under progressive drought, the amount of leaf NtHSP70-1 was correlated with maintenance of optimum water content, with contents being higher in the leaves of dehydrated transgenic sense plants than in those of either the control (vector-only) or the transgenic antisense plants. Moreover, the expression of CaERD15 was considerably reduced in tobacco plants that over-expressed NtHSP70-1. These results suggest that elevated levels of NtHSP70-1 can confer drought-stress tolerance.

Spikelet Proteomic Response to Combined Water Deficit and Heat Stress in Rice (Oryza sativa cv. N22)

“…Comparing the protein and transcript expression pattern for these two genes, we found differential gene regulation both at the transcriptional and translational phase in response to heat and drought stress. Evidently, HSPs are found to protect plants against various environmental stresses such as heat shock resulting in increasing sHSP expression providing cross-resistance in plants to water deficit (Sun et al 2001;Cho and Hong 2006), chilling injury (Sebehat et al 1996;Sato et al 2001), salt shock (Harrington and Alm 1988), and oxidative injury (Banzet et al 1998). Sato and Yokoya (2007) showed increased tolerance of rice seedlings of water deficit after prior exposure to heat stress at 42°C for 24 h; overexpression of HSPs increased tolerance of water deficit in tobacco (Cho and Hong 2006) and water deficit and salt in Arabidopsis (Sun et al 2001).…”

“…Evidently, HSPs are found to protect plants against various environmental stresses such as heat shock resulting in increasing sHSP expression providing cross-resistance in plants to water deficit (Sun et al 2001;Cho and Hong 2006), chilling injury (Sebehat et al 1996;Sato et al 2001), salt shock (Harrington and Alm 1988), and oxidative injury (Banzet et al 1998). Sato and Yokoya (2007) showed increased tolerance of rice seedlings of water deficit after prior exposure to heat stress at 42°C for 24 h; overexpression of HSPs increased tolerance of water deficit in tobacco (Cho and Hong 2006) and water deficit and salt in Arabidopsis (Sun et al 2001). The molecular and physiological responses in Arabidopsis (Rizhsky et al 2004) and tobacco (Rizhsky et al 2002) were similar to those in rice in many ways when subjected to a combined water-deficit stress and heat stress, suggesting a possible conserved defense mechanism across crops in response to abiotic stresses.…”

Proteomic analysis of stress-related proteins in rice seeds during the desiccation phase of grain filling

“…A 70 kDa HSP is up-regulated in rice seedlings treated with ABA (Zou et al 2009). In addition, drought tolerance is increased by overexpression of a tobacco HSP70 (Cho and Hong 2006). Therefore, 70 kDa HSP in rice seeds may play an important role in the acquisition of desiccation tolerance, but only at the beginning of dehydration.…”

Influence of abiotic stresses on plant proteome and metabolome changes

“…HSP90 and HSP70 were found to be required for stomata closure and modulation of transcriptional responses to abscisic acid (Clèment et al 2011); thus, they may be crucial for enhanced drought-tolerance. Tobacco plants overexpressing NtHSP70-1 demonstrated higher tolerance to water deficiency (Cho and Hong 2006). In the analysis of the changes in the proteome of grasspea exposed to salinity and drought, HSP 70 was found to be up-regulated in the plants exposed to increased salinity and drought (Chattopadhyay et al 2011).…”