PARENT SESSION
Posters P1B Photo-oxidative stress, photoinhibition. Abstracts (394-443)

Expression of Arabidopsis SR protein in response to various types of environmental stresses. Kazuya Yoshimura^{*,1, 2}, Noriaki Tanabe², Minako Asano², Akiho Yokota¹, Shigeru Shigeoka², ¹ Graduate School of Biological Sciences, Nara Institute of Science Technology, Nara, Ikoma, Japan² Department of Food and Nutrition, Faculty of Agrigulture, Kinki University, Nara, Nara, Japan

ABSTRACT- Alternative splicing is one of the most important sources of functional diversity of proteins in eukaryotes. To cope with environmental stresses and to prevent invasion by pathogens, plant metabolism must be flexible and dynamic. Interestingly, the genes associated with various stress responses seem to be prone to alternative splicing in higher plants. Therefore, it is likely that plants may have evolved a plant-specific regulatory mechanism including alternative splicing of stress-responsive genes. Among splicing factors, the serine/arginine-rich (SR) protein family has been shown to play important roles in both the constitutive splicing and the selection of alternative splice sites. Nineteen types of genes encoding SR proteins occur in the Arabidopsis genome. To assess the contribution of SR proteins to the alternative splicing mechanisms involved in coping with environmental fluctuations, changes of the transcript levels of Arabidopsis SR proteins in response to several types of stress were studied. The transcript levels of both atSR41.2 and atSRp30/SF2/ASF increased markedly after 15 min of high light irradiation (400 E m^-2 s^-1) and reached a peak after 1 h, while no significant changes were observed in the transcript levels of all other SR proteins. The transcript level of atSRp30/SF2/ASF was also induced by salinity, whereas it was suppressed by low temperature. In addition, the transcript levels of atRSp40, atRSZp22, atRSZp21a, and atRSZp32 were induced by low temperature. These stress-responsive SR proteins have been classified into the types of ASF (atSRp30/SF2/ASF and atRSp40), SCL (atSR41.2), and 9G8/SRp20 (atRSZp22, atRSZp21a, and atRSZp32). Therefore, it is likely that each stress-responsive SR protein in higher plants may be related to the regulation of respective alternative splicing events responsive to distinct stress conditions. We are progressing toward identifying the genes whose alternative splicing efficiencies are regulated by the stress-responsive SR proteins.

KEY WORDS: SR protein, Gene expression, Alternative splicing, Oxidative stress