Regulation of melanin biosynthesis during appressorium formation inColletotrichum lagenarium |
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| Affiliation: | 1. Programa de Pós-Graduação em Ciências da Saúde: Infectologia e Medicina Tropical, Faculdade de Medicina, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil;2. Programa de Pós-Graduação em Ciências da Saúde, Universidade do Extremo Sul Catarinense, Criciúma, Santa Catarina, Brazil;3. Departamento de Patologia Clínica, COLTEC, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil;1. Institute of Environment and Sustainable Development in Agriculture, Chinese Academy of Agricultural Sciences, Key Laboratory of Agro-Environment, Ministry of Agriculture, Beijing, PR China;2. Institute for Global Food Security, Queen''s University Belfast, Biological Sciences, 19 Chlorine Gardens, Belfast BT9 5DL, UK;3. Shanghai Synchrotron Radiation Facility, Shanghai Advanced Research Institute, Chinese Academy of Sciences, Shanghai 201204, PR China;4. School of Chemistry and Chemical Engineering, Harbin Institute of Technology, MIIT Key Laboratory of Critical Materials Technology for New Energy Conversion and Storage, Harbin 150080, PR China;1. Center for Research and Advanced Studies of the National Polytechnic Institute, Ciudad Victoria, Tamaulipas, Mexico;2. Faculty of Engineering and Sciences, Autonomous University of Tamaulipas, Ciudad Victoria, Tamaulipas, Mexico;1. Department of Ecology, School of Life Sciences/State Key Laboratory of Biocontrol, Sun Yat-sen University, Guangzhou 510275, PR China;2. School of Forestry and Environmental Studies, Yale University, New Haven, CT, USA;3. Guangdong Ecological Meteorology Center, Guangzhou 510080, PR China |
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| Abstract: | Regulation of melanin biosynthesis in relation to appressorium differentiation ofColletotrichum lagenarium was investigated. When spores of the parent strain 104-T were incubated at 24°C, appressorial pigmentation started at 6 h of incubation and was preceded by appressorim swelling; appressoria were darkly pigmented at 12 h of incubation. The same time course of appressorial pigmentation was observed in albino mutant 79215 when scytalone, a natural precursor of melanin biosynthesis, was applied before the swelling of appressoria. In accordance with this result, [14C]scytalone was not incorporated into germlings of albino mutant 79215 before the swelling of appressoria. Cycloheximide applied 1 h or more after incubation of spores of the parent strain 104-T, or of albino mutant 79215 treated with scytalone, inhibited neither appressorium formation nor appressorial pigmentation. These results indicate that enzymes involved in melanin biosynthesis subsequent to scytalone are preexisting enzymes or synthesized as inactive forms during 1 h of incubation, and that they are activated during appressorium differentiation. In addition, an early step(s) prior to scytalone in the melanin biosynthesis of appressoria was temperature sensitive; when colorless appressoria of the parent strain 104-T formed during 6 h of incubation at 24°C were postincubated at 32°C, the appressoria did not melanize, whereas application of scytalone to the postincubation at 32°C permitted melanization of the appressoria. Also, albino mutant 79215 formed melanized appressoria during postincubation at 32°C in the presence of scytalone. These results indicate that high temperatures inhibit melanin biosynthesis by inhibiting one or more steps prior to scytalone synthesis. |
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