Biochemical and physiological characterizations of a rice (Oryza sativa L.) apoplastic thaumatin-like protein

• Main Authors: Huei-Lan Huang, 黃蕙蘭
• Other Authors: Yu-Chi Wang
• Format: Others
• Language: zh-TW
• Published: 2001
• Online Access: http://ndltd.ncl.edu.tw/handle/54920247058234884719

碩士 === 國立臺灣師範大學 === 生物研究所 === 89 === ABSTRACT Under conditions of normal growth, suspension-cultured rice cells secreted some different proteins into liquid Murashige-Skoog medium. Among them, a protein with a monomeric mass of 29 kDa (designated Osm29 protein) has a N-termintal amino acid sequence homologous to some thaumatin-like proteins in plants. The purposes of this study were to purify the Osm29 protein and to produce antibodies of it . In addition, biochemical and physiological characterizations of the Osm29 protein were also conducted. With regard to purification of the Osm29 protein, a scheme using in combination of ammonium sulfate fractionation (60-80% saturation) and Mono S chromatography were developed. By using this protocal the Osm29 protein was purified to near homogeneity with a purification factor of 39-fold and the protein yield was about 0.64% of the total secreted proteins. With regard to the biochemical properties of Osm29 protein, it appears to be a non-glycosylated basic protein with 5 isomers varying in pI value. According to the results of peptide mapping, the amino acid sequence of the five isoforms were highly comparable between each other. With regard to the physiological properties of the Osm29 protein, it is present in the medium of cell culture, but not detectable in extracts of rice embryo and various organs of rice young seedlings. The secretion of Osm29 protein in culture medium can be rapidly induced by treatment of salicylic acid and by Sarocladium oryzae infection, but not by treatment of methyl jasmonic acid and Rhizoctonia solani infection. In an antifungal bioassay, Osm29 protein did not inhibit the growth of Rhizoctonia solani, Bipolaris oryzae, and Sarocladium oryzae, but at the dose of 150 μg, it exhibited growth-retarding effects on Bipolaris oryzae.