Trichoderma longibrachiatum T6: A nematocidal activity of endochitinase gene exploration and its function identification

Endochitinase is a natural extracellular protein in Trichoderma longibrachiatum T6, which can degrade the eggshell of Heterodera avenae significantly, however the related genes that coding this protein was rarely characterized. In the present study, the endochitinase 18-5 gene (T6-Echi18-5) of T. longibrachiatum T6 was cloned and sequenced. The expression level of T6-Echi18-5 gene in T. longibrachiatum T6 was induced and increased after the H. avenae cysts inoculation. The full-length cDNA sequence of T6-Echi18-5 was 1671 bp that contained an ORF of 1275 bp, corresponding to 424 amino acids with a 45.9 kDa molecular weight. A single band of 60.04 kDa was detected and identified using SDS-PAGE and Western blot analysis after transferring the T6-Echi18-5 gene to Escherichia coli BL21 Rosetta (DE3). The concentration of purified recombinant T6-Echi18-5 protein was 1.53 mg center dot ml 1, and the optimal temperature and pH were 50 degrees C and 5.0, respectively. The eggshell and content were dissolved and exuded from 4 to10 days after treatment with the purified recombinant T6-Echi18-5 protein. The relative inhibition rate of eggs hatching was 86.79 % at 12 days after treatment. Our study demonstrated the key role of T6-Echi18-5 gene in degrading the H. avenae eggshell and inhibiting the eggs hatching.