104(2)_str23

 

ISSN 1392-3196 / e-ISSN 2335-8947
Zemdirbyste-Agriculture, vol. 104, No. 2 (2017), p. 179–184
DOI  10.13080/z-a.2017.104.023

Evaluation of chitinase enzyme in fungal isolates obtained from golden potato cyst nematode (Globodera rostochiensis)

Khadijeh ABBASI, Doustmorad ZAFARI, Robert WICK

Abstract

The structure of nematode eggshell indicates that proteases and chitinases are necessary for infection by nematophagous fungi, and most of them produce these enzymes. Therefore the aim of this study was to assay chitinase activity in 34 isolates of various species of fungi obtained from golden potato cyst nematode (Globodera rostochiensis), as the most important potato pest, over two days of fungal growth (24 and 96 h). Chitinase specific activity was determined by measuring the release of reducing saccharides from colloidal chitin by the N-acetyl-glucosamine-dinitrosalicylate method at 540 nm. Colorimetry based on image processing technique was used to discover colour changes in minimal synthetic medium for validation of chitinase activity. The 34 isolates were identified based on morphological and molecular features including internal transcribed spacer (ITS) regions of ribosomal DNA. Results of the chitinase specific activity measurement showed the chitinase specific activity in all of them for 96 h was higher than for 24 h. Among isolates, the maximum and minimum chitinase specific activity respectively belonged to isolate 154 (0.56 U mg-1) and isolate 6 (0.15 U mg-1) in 24 h, also isolate 113 (1.02 U mg-1) and isolate 6 (0.40 U mg-1) in 96 h. Colorimetric results confirmed that enzyme activity was associated with colour changes. The 34 fungal isolates were classified in 11 genera most of which belonged to Fusarium. Finally, two isolates, 113 (Fusarium oxysporum) and 154 (Trichoderma atroviridae), with the highest chitinase enzyme activity are introduced as potent isolates to control the golden potato cyst nematode that can be used for chitinase enzyme production which is supposed to be used in commercial formulation.

Key words: chitinase, fungi, Globodera rostochiensis, potato.

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