Construction of Beauveria bassiana T-DNA insertion mutant collections and identification of thermosensitive and osmosensitive mutants.

OBJECTIVE

This study was to identify genes involved in thermotolerance and osmotolerance of Beauveria bassiana.

METHODS

A collection of T-DNA random insertion mutagenesis was constructed and thermosensitive and osmosensitive mutants were screened. The DNA fragments flanking to inserted T-DNA sequence in the mutants were isolated by using Y-shaped adaptor dependent extension (YADE) method.

RESULTS

Five mutants impaired in thermotolerance or osmotolerance were identified and characterized. Mutant 212 and 2550 could not grow at 32%, while mutants 139, 2737 and 2812 showed depressed growth under osmotic stress. Conidial viabilities of 212 was decreased by 23%, 52% and 21% after stressed by ultraviolet, heat shock, and H2O2 oxidation, respectively, compared to the wild-type strain. Virulence of mutant 212 and 2737 against aphids Myzus persicae were reduced by 12% and 40%, respectively. Sequencing analysis indicated that two function-unknown genes were interrupted by insertion of T-DNA in mutant 212 and 2737. In other three mutants, the insertions are located in the non-encoding regions.

CONCLUSION

The results demonstrate the successful use of T-DNA insertion mutagenesis in identification of genes involved in thermotolerance and osmotolerance of B. bassiana.