关键词: 白腐菌, 木质素酶, 纤维素酶, TRAP分子标记, 遗传变异

Abstract: [Objective] Lignocellulose is an important renewable resource in the world, and white-rot fungi have special advantages in degradation of this resource. We studied the biological characteristics, enzymatic activity and genetic diversity of fungi, and analyzed systematically the relationship between woody cellulase expression and the related gene polymorphism, in order to provide a theoretical basis of breeding and molecular mechanisms of white-rot fungi. [Method] Three white-rot fungi, Trametes versicolor, Phellinus igniarius and Ganoderma tsugae, were used to study the growth rate in solid medium under different culture conditions and the biomass in liquid medium. Colorimetric methods were used to measure activities of five kinds of cellulose enzymes, and the target region amplification polymorphism (TRAP) was applied to analyze polymorphisms of three kinds of lignocellulose-degrading enzyme genes. [Result] The results showed that growth rate of the three white-rot fungi was successively Trametes versicolor > Phellinus igniarius > Ganoderma tsugae at different temperatures (23°C and 28°C) on the PDA medium. The growth rate of Trametes versicolor and Phellinus igniarius was higher at 28°C than at 23°C, while this was inverse for Ganoderma tsugae. The biomass of Trametes versicolor in the liquid medium was highest among the three fungi. Spectrophotometry was used to detect the activities of the five ligocellulose enzymes produced by three fungi. Sawdust could markedly increase ligninase activities, however cellulose activity induced by maize straw was higher than that by sawdust as carbon source. The activity of laccase was highest in all the three ligninases, manganese peroxidase was the second and lignin peroxidase was the last. There was no significant difference in the cellulases activities among the three fungi, but exo-cellulase was significantly higher than endo-cellulase. Trametes versicolor had the highest ligninase activity, and the others produced higher cellulase activity. In addition, a total of 109 bands were amplified by 6 primers related to ligninase gene, including 79 polymorphic bands, and the polymorphism ratio was 71.34%. With 11 primers related to cellulase gene, 198 fragments were obtained, of which 140 were polymorphic bands (70.70%). [Conclusion] There existed relatively high genetic differences among these three kinds of white-rot fungi using the detection of growth rate, biomass, enzyme activities and molecular marker. The values of enzyme activities had no corresponding relationship with enzyme gene polymorphism. However, cellulose activities were consistent among fungi, and the same in gene polymorphism. These results would be helpful for the study on mechanism of wood decayed by white-rot fungi.

Key words: white-rot fungi, ligninase, cellulase, TRAP, genetic variation