Functional Analysis Of The Melanin Biosynthesis Gene St4HNR In Setosphaeria Turcia And Study Of Extracellular Melanin

To confirm the relationship between DHN melanin biosynthesis and pathogenicity of Setosphaeria turcica, in this research the gene encoding 1,3,6,8 - 4-hydroxy-naphthalene reductase(4HNR) was preliminarily identified that it play an important role in melanin biosynthesis.In the study, PEG4000-mediated method were used to transform protoplasts of S. turcica and 46 transformants were obtained by screened from medium containing 1% hygromycin, clony color of one of the transformants was gray-white, which was identified as a mutant strain through PCR method. Compared with wild type, the mutant showed a lighter colony color, and its virulence and pathogenicity decreased, and there was no spore produced. This can provide a theoretical basis for further explore the pathogensis of S. turcicca, and the regulation of melanin to appressorium penetration on the gene level, and the designation of new antifungal agents.Melanin can be classified to extracellular and intracellular melanin by its location. In this study, we preliminarily explored the properties and the production condition of S. turcica extracellular melanin. The extracellular melanin of S. turcica was extracted useing acid-base precipitation method and it was proved to be DOPA melanin by infrared spectroscopy. Its production was promoted in the shaking culture when 27.6μmol/L tyrosine and 26.42μmol/L tricyclazole was added. But the other condition including Cu2+, glucose, and pH, they didn't have an important impact on the production of extracellular melanin. This provide an support for further explore the relationship between melanin and pathogenicity of S. turcica.