Physiological implication of intracellular trehalose and mannitol changes in response of entomopathogenic fungus <Emphasis Type="Italic">Beauveria bassiana</Emphasis> to thermal stress |
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Authors: | Qian Liu Sheng-Hua Ying Ming-Guang Feng Xin-Hang Jiang |
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Institution: | (1) Institute of Microbiology, College of Life Sciences, Zhejiang University, 310058 Hangzhou, Zhejiang, People’s Republic of China;(2) Equipment and Technology Service Platform, College of Life Sciences, Zhejiang University, 310058 Hangzhou, Zhejiang, People’s Republic of China |
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Abstract: | To explore possible role of intracellular trehalose accumulation in fungal tolerance to summer-like thermal stress, 3-day
colonies of Beauveria bassiana grown on a glucose-free medium at 25°C were separately exposed to 35, 37.5 and 40°C for 1–18 h, respectively. Trehalose accumulation
in stressed mycelia increased from initial 4.2 to 88.3, 74.7 and 65.5 mg g−1 biomass after 6-h stress at 35, 37.5 and 40°C, respectively, while intracellular mannitol level generally declined with higher
temperatures and longer stress time. The stress-enhanced trehalose level was significantly correlated to decreased trehalase
activity (r
2 = 0.73) and mannitol content (r
2 = 0.38), which was inversely correlated to the activity of mannitol dehydrogenase (r
2 = 0.41) or mannitol 1-phosphate dehydrogenase (r
2 = 0.30) under the stresses. All stressed cultures were successfully recovered at 25°C but their vigor depended on stressful
temperature, time length and the interaction of both (r
2 = 0.98). The highest level of 6-h trehalose accumulation at 35°C was found enhancing the tolerance of the stressed cultures
to the greater stress of 48°C. The results suggest that the trehalose accumulation result partially from metabolized mannitol
and contribute to the fungal thermotolerance. Trehalase also contributed to the thermotolerance by hydrolyzing accumulated
trehalose under the conditions of thermal stress and recovery. |
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Keywords: | Beauveria bassiana Thermal stress Trehalose Trehalase Mannitol Mannitol 1-phosphate dehydrogenase Mannitol dehydrogenase Fungal thermotolerance |
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