A nuclear-localized HSP70 confers thermoprotective activity and drought-stress tolerance on plants

Abstract

To investigate the function of nuclear-localized plant HSP70, we used NtHSP70-1 isolated from Nicotiana tabacum. The subcellular localization of NtHSP70-1 was identified by fluorescence microscopy for NtHSP70-1/GFP or smGFP fusion proteins in onion epidermal cells, obtained using particle gun bombardment. To analyze the drought-stress tolerance and thermoprotective role of NtHSP70-1, we obtained transgenic tobacco plants that constitutively expressed elevated levels of NtHSP70-1 as well as transgenic plants containing either the vector alone or else having NtHSP70-1 in the antisense orientation. From analysis for genomic DNA in transgenic seedlings after heat stress, NtHSP70-1 helps to prevent the fragmentation and degradation of nuclear DNA during heat stress. In addition, seedlings constitutively overexpressing NtHSP70-1 grew to be healthy plants, whereas transgenic vector or antisense seedlings resulted in death after heat-/drought-stress.

Functional analysis of Hsp70 superfamily proteins of rice (Oryza sativa)

“…Eleven Hsp70 proteins predicted to be localized to cytosol or nucleus by different tools were considered as nucleo/cytosolic considering the reports that cytosolic Hsp proteins relocate to nucleus in response to heat stress (Kose et al 2012). Under heat stress, nuclear localized Hsp70 prevented fragmentation of DNA and provided thermotolarance (Cho and Choi 2009). Qi et al (2011) reported two mtHsp70 proteins and Oono et al (2010) reported ten BiPs proteins in rice.…”

Overexpression of a Brassica campestris HSP70 in tobacco confers enhanced tolerance to heat stress

“…(Cho and Choi 2009). These stresses simultaneously act on the plants, causing cell injury and producing secondary harm such as osmotic and oxidative damage (Wang et al 2003).…”

Heat shock protein 70 regulates the abscisic acid-induced antioxidant response of maize to combined drought and heat stress

“…This provides new insights into the mechanism of cytoprotection induced by HSP70. In plants, H 2 O 2 accumulation also leads to HSPs accumulation (Dat et al 2000;Mittler 2002), especially HSP70 is induced quickly by ABA treatment (Cho and Hong 2006), drought stress, heat shock, and their combination (Oono et al 2003;Rizhsky et al 2002Rizhsky et al , 2004Cho and Choi 2009). Increased HSP70 synthesis results in a marked increase in stress tolerance and cytoprotection.…”

“…Increased HSP70 synthesis results in a marked increase in stress tolerance and cytoprotection. Tansgenic tobacco seedlings that over-expressed HSP70 exhibits tolerance to drought and heat stress (Cho and Choi 2009). However, it is unclear that to what extent and in what way ABA and HSP70 cooperate in protection against ROS-induced cytotoxicity in plants exposed to combined drought and heat stress.…”