TITLE	Chitinase isoenzymes in near-isogenic wheat lines challenged with Russian wheat aphid, exogenous ethylene, and mechanical wounding
AUTHOR	A-M. Botha Department of Botany and Genetics, Faculty of Science, University of the Orange Free State, P. O. Box 339, Bloemfontein, 9300, South Africa M.A.C. Nagel Department of Botany and Genetics, Faculty of Science, University of the Orange Free State, P. O. Box 339, Bloemfontein, 9300, South Africa A.J. Van der Westhuizen Department of Botany and Genetics, Faculty of Science, University of the Orange Free State, P. O. Box 339, Bloemfontein, 9300, South Africa F.C. Botha Department of Biotechnology, SASEX, Mount Edgecombe, 4300, South Africa
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ABSTRACT	Russian wheat aphid (RWA) infestation, ethylene exposure, and mechanical wounding resulted in differential expression of chitinase (EC 3.2.1.14) isoenzymes in near-isogenic wheat lines susceptible and resistant to the RWA. Isoelectric focusing (IEF) and non-denaturing IEF gels revealed the existence of multiple isoenzymes of chitinase with a wide range of isoelectric points, ranging from 9.7 (basic) to 3.4 (acidic). Seven bands were observed in the resistant and susceptible untreated plants (pI values of approximately 9.5, 9.2, 8.8, 8.5, 8.4, 7.8 and 5.0) on IEF gels. RWA infestation resulted in the expression of an additional band (approximately pI 5.5) whereas ethylene exposure resulted in the induction of two additional isoenzymes (approximately pI 4.1 and 6.8). Mechanical wounding also induced the isoenzyme with pI of 4.1. Isoelectrical focusing (IEF) in liquid medium confirmed the multiple isoenzymes obtained with IEF gels. Five different peaks with chitinase activity were detected in control plants (pI values of 9.2, 7.8, 5.0, 4.1, and 3.6) after IEF. RWA infestation, ethylene and mechanical wounding caused the induction of additional isoenzyme peaks. Differential expression of chitinolytic activity was also observed between the near-isogenic wheat lines.
KEYWORD	Chitinase expression; Ethylene; Hydrolase; Isoelectric focusing; Isoenzymes; Mechanical wounding; Russian wheat aphid infestation;
ARTICLE INFO	Botanical Bulletin of Academia Sinica, Volume 39 Number 2 April 1998, page 99-106, 8 pages
PUBLISHER	Institute of Plant and Microbial Biology, Academia Sinica, Taipei, Taiwan, Republic of China