Ashita Hamachi1, Masahiro Nisihara2, Shiori Saito1, Hojun Rim1, Hideyuki Takahashi2, Monirul Islam3, Takuya Uemura1, Toshiyuki Ohnishi4,5, Rika Ozawa6, Massimo E Maffei3, Gen-Ichiro Arimura7. 1. Department of Biological Science and Technology, Faculty of Industrial Science and Technology, Tokyo University of Science, 6-3-1 Niijuku, Katsushika-ku, Tokyo, 125-8585, Japan. 2. Iwate Biotechnology Research Center, Kitakami, Iwate, 024-0003, Japan. 3. Department of Life Sciences and Systems Biology, Plant Physiology Unit, University of Turin, Via Quarello15/A, I-10135, Turin, Italy. 4. College of Agriculture, Academic Institute, Shizuoka University, Shizuoka, 422-8529, Japan. 5. Research Institute of Green Science and Technology, Shizuoka University, Shizuoka, 422-8529, Japan. 6. Center for Ecological Research, Kyoto University, Otsu, 520-2113, Japan. 7. Department of Biological Science and Technology, Faculty of Industrial Science and Technology, Tokyo University of Science, 6-3-1 Niijuku, Katsushika-ku, Tokyo, 125-8585, Japan. garimura@rs.tus.ac.jp.
Abstract
MAIN CONCLUSION: Transgenic tobacco plants overexpressing the monoterpene alcohol geraniol synthase exhibit hypersensitivity to thermal stress, possibly due to suppressed sugar metabolism and transcriptional regulation of genes involved in thermal stress tolerance. Monoterpene alcohols function in plant survival strategies, but they may cause self-toxicity to plants due to their hydrophobic and highly reactive properties. To explore the role of these compounds in plant stress responses, we assessed transgenic tobacco plants overexpressing the monoterpene alcohol geraniol synthase (GES plants). Growth, morphology and photosynthetic efficiency of GES plants were not significantly different from those of control plants (wild-type and GUS-transformed plants). While GES plants' direct defenses against herbivores or pathogens were similar to those of control plants, their indirect defense (i.e., attracting herbivore enemy Nesidiocoris tenuis) was stronger compared to that of control plants. However, GES plants were susceptible to cold stress and even more susceptible to extreme heat stress (50 °C), as shown by decreased levels of sugar metabolites, invertase activity and its products (Glc and Fru), and leaf starch granules. Moreover, GES plants showed decreased transcription levels of the WRKY33 transcription factor gene and an aquaporin gene (PIP2). The results of this study show that GES plants exhibit enhanced indirect defense ability against herbivores, but conversely, GES plants exhibit hypersensitivity to heat stress due to suppressed sugar metabolism and gene regulation for thermal stress tolerance.
MAIN CONCLUSION: Transgenic tobacco plants overexpressing the monoterpene alcohol geraniol synthase exhibit hypersensitivity to thermal stress, possibly due to suppressed sugar metabolism and transcriptional regulation of genes involved in thermal stress tolerance. Monoterpene alcohols function in plant survival strategies, but they may cause self-toxicity to plants due to their hydrophobic and highly reactive properties. To explore the role of these compounds in plant stress responses, we assessed transgenic tobacco plants overexpressing the monoterpene alcohol geraniol synthase (GES plants). Growth, morphology and photosynthetic efficiency of GES plants were not significantly different from those of control plants (wild-type and GUS-transformed plants). While GES plants' direct defenses against herbivores or pathogens were similar to those of control plants, their indirect defense (i.e., attracting herbivore enemy Nesidiocoris tenuis) was stronger compared to that of control plants. However, GES plants were susceptible to cold stress and even more susceptible to extreme heat stress (50 °C), as shown by decreased levels of sugar metabolites, invertase activity and its products (Glc and Fru), and leaf starch granules. Moreover, GES plants showed decreased transcription levels of the WRKY33 transcription factor gene and an aquaporin gene (PIP2). The results of this study show that GES plants exhibit enhanced indirect defense ability against herbivores, but conversely, GES plants exhibit hypersensitivity to heat stress due to suppressed sugar metabolism and gene regulation for thermal stress tolerance.
Authors: Joost Lücker; Wilfried Schwab; Maurice C R Franssen; Linus H W Van Der Plas; Harro J Bouwmeester; Harrie A Verhoeven Journal: Plant J Date: 2004-07 Impact factor: 6.417
Authors: Joost Lücker; Wilfried Schwab; Bianca van Hautum; Jan Blaas; Linus H W van der Plas; Harro J Bouwmeester; Harrie A Verhoeven Journal: Plant Physiol Date: 2004-01-08 Impact factor: 8.340