Plant and Cell Physiology Advance Access first published online on January 4, 2008
This version published online on January 4, 2008
Plant and Cell Physiology, doi:10.1093/pcp/pcm180
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Programmed proteome response for drought avoidance/tolerance in the root of a C3 xerophyte (wild watermelon) under water deficits
Graduate School of Biological Sciences, Nara Institute of Science and Technology
*Corresponding author: Dr. Kinya Akashi, Nara Institute of Science and Technology, Graduate School of Biological Sciences, 8916-5 Takayama, Ikoma, Nara 630-0101, Japan, Tel: +81 743 72 5560, Fax: +81 743 72 5569, E-mail: akashi{at}bs.naist.jp
| Abstract |
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Water availability is a critical determinant for the growth and ecological distribution of terrestrial plants. Although some xerophytes are unique for their highly developed root architecture and the successful adaptation to the arid environments, virtually nothing is known for the molecular mechanisms underlying this adaptation. Here, we report physiological and molecular responses of wild watermelon (Citrullus lanatus sp.), which exhibits extraordinarily high drought resistance. At the early stage of drought stress, root development of wild watermelon was significantly enhanced compared to that of the irrigated plants, indicating the activation of a drought avoidance mechanism for absorbing water from deep soil layers. Consistent with this observation, comparative proteome analysis revealed that many proteins induced in the early stage of drought stress are involved in root morphogenesis and carbon/nitrogen metabolisms, which may contribute to the drought avoidance via the enhancement of root growth. On the other hand, lignin synthesis-related proteins and molecular chaperones, which may function in the enhancement of physical desiccation tolerance and maintenance of protein integrity, respectively, were induced mostly at the later stage of drought stress. Our findings suggest that this xerophyte switches survival strategies from drought avoidance to drought tolerance during the progression of drought stress, by regulating its root proteome in a temporally programmed manner. This study provides new insights into the complex molecular networks within plant roots involved in the adaptation to adverse environments.
Keywords: Drought - proteome - Root - Wild watermelon - xerophyte
1Present address: Department of Food and Nutritional Science, College of Bioscience and Biotechnology, Chubu University, 1200 Matsumoto-cho, Kasugai, Aichi 487-8501, Japan
(Received October 15, 2007; Accepted December 20, 2007)
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