Changes in Composition of Soluble Intercellular Proteins Isolated from Healthy and TMV-Infected Nicotiana tabacum L. cv. Xanthi-nc

Abstract

Changes in ribonucleases (RNases), phosphomonoesterase (PME), phosphodiesterase (PDE), glucose-6-phosphate dehydrogenase (G6P DH), polyphenoloxidases, peroxidases and proteases activity and PR-proteins composition in leaf tissue and intercellular fluid (ICF) isolated from leaf tissue of healthy and TMV-infected hypersensitive tobacco (Nicotiana tabacum L. cv. Xanthi-nc) plants (non-inoculated leaves) were studied. The amount of the proteins and the enzymes of intercellular space was less than 3 % of the total amount of proteins and the enzymes found in homogenate of healthy leaves. The TMV infection did not significantly change this observation. The great increase in the activities of the enzymes was observed in homogenates of the infected leaves, especially of the enzymes involved in biosynthesis of precursors needed for virus multiplication (G6P DH, RNase, PME, PDE). This is in contrast with the activities of the enzymes of ICF, which were only partly increased. The ICF proteins of infected plants were separated by means of ion exchange chromatography on DEAE cellulose. The isozymes of peroxidase, polyphenoloxidase, PME and PDE were identified. Using discontinuous nondenaturating polyacrylamide gel electrophoresis of DEAE cellulose fractions, the detection of isozymes of peroxidases and PR-proteins was performed. By means of SDS-PAGE the molecular masses of PR-proteins were identified: 15 - 16 kDa (group 1), 27 - 28 kDa (group 3: chitinases) and 36 - 40 kDa (group 2a: β-1,3-glucanases).