Poster: Temperature Responses

Abs # 185: Fatty acid desaturases cloned from african violet (Saintpaulia ionantha) are related to the chilling sensitivity of this plant

Presenter:	Yoshida, Rin
Authors	Yoshida, Rin  (B)   Kanechi, Michio  (B)   Uno, Yuichi  (A)   Inagaki, Noboru  (B)
Affiliations:	(A): Faculty of Agriculture, Kobe University (B): The Graduate School of Science and Technology, Kobe University

African violet (Saintpaulia ionantha) originated in Africa, which is hypersensitive to chilling temperature, appears brown-yellow spots (leaf spots) on the leaf surface as chilling injuries occurred by an overhead irrigation with cold water. The fatty acid composition of cell membrane lipid is closely related to the chilling sensitivity of plants. The plant species with high ratio of unsaturated fatty acid composition can keep their membranes fluid under chilling temperature, therefore they are tolerant to chilling. We have isolated two c-DNAs encoding fatty acid desaturases from the c-DNA library of African violet (cv. Tomahawk) leaf, which was ranked among the least tolerant varieties we had tested. It has been recognized that their ORF regions shared high sequence similarities with omega-3 fatty acid desaturases and omega-6 fatty acid desaturases of potato (Solanum tuberosum), soybean (Glycine max), and sesame (Sesamum indicum). Furthermore, northern analysis has been carried out to compare their expressions between cultivars (chilling sensitive and chilling tolerant) treated by an abrupt drop in leaf temperature and to clarify their expression patterns throughout leaf unfolding. Finally, we considered the relationship between the severity of leaf spot injury and the fatty acid compositions of leaves by gas chromatography analysis.