TITLE	Over-expression of Arabidopsis thaliana heat shock factor gene (AtHsfA1b) enhances chilling tolerance in transgenic tomato
AUTHOR	Hsiao-Yuan Li Institutes of BioAgricultural Sciences, Academia Sinica, Nankang, Taipei, Taiwan 115, R.O.C. Chiung-Swey Chang Institutes of BioAgricultural Sciences, Academia Sinica, Nankang, Taipei, Taiwan 115, R.O.C. Liang-Suei Lu Institutes of BioAgricultural Sciences, Academia Sinica, Nankang, Taipei, Taiwan 115, R.O.C. Chien-An Liu Asian Vegetable Research and Development Center, Tainan, Taiwan 741, R.O.C. Ming-Tsair Chan Institutes of BioAgricultural Sciences, Academia Sinica, Nankang, Taipei, Taiwan 115, R.O.C. Yee-Yung Charng Institutes of BioAgricultural Sciences, Academia Sinica, Nankang, Taipei, Taiwan 115, R.O.C.
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ABSTRACT	Heat shock pre-treatment or heat acclimation can enhance the subsequent chilling tolerance of many plant species. However, the exact mechanism is currently unknown. Transgenic tomato plants harboring an Arabidopsis thaliana HsfA1b (AtHsfA1b) and b-glucuronidase (gusA) fusion gene under the control of a constitutive CaMV35S promoter were generated to evaluate whether heat shock factor (Hsf), a major transcription regulator of heat shock response, is involved in heat shock-induced chilling tolerance. The transcripts or protein product of heat-shock induced genes in the transgenic plants highly expressing AtHsfA1b-gusA accumulated to higher levels than those of the wild-type or gusA transgenic plants under non-heat shock conditions. This suggests that AtHsfA1b-GUS can cross-talk with the heat shock responsive machinery in transgenic tomato plants. In addition, the specific activity of soluble isoforms of ascorbate peroxidase of the AtHsfA1b-gusA transgenic plants was about twofold higher than that of the wild-type or gusA transgenic plants under non-heat stress conditions. Without heat acclimation, seedlings of the AtHsfA1b-gusA transgenic tomato lines showed a significantly higher level of thermal and chilling tolerance than that of the wild-type or gusA transgenic plants. Based on these results, we suggest that Hsf may play a pivotal role in heat-shock-induced chilling tolerance, and constitutive expression of the transcription regulatory gene in chilling sensitive crops may be useful in improving tolerance against chilling stress.
KEYWORD	Chilling stress; Heat shock factor; Transgenic tomato;
ARTICLE INFO	Botanical Bulletin of Academia Sinica, Volume 44 Number 2 April 2003, page 129-140, 12 pages
PUBLISHER	Institute of Plant and Microbial Biology, Academia Sinica, Taipei, Taiwan, Republic of China