Potential applications of filamentous fungus derived β-defensin-like antifungal proteins in agriculture

Many filamentous fungi are postharvest and destructive plant pathogens and are thus responsible for enormous crop losses worldwide. The antifungal proteins secreted by filamentous fungi are promising agents for prevention of fungal diseases in the agriculture. The extracellular β-defensin-like antifungal proteins derived from ascomycetous filamentous fungal species are especially interesting in this respect because of their chemical and biological properties. The main features of these extracellular proteins are a low molecular mass, a basic character, and the presence of 6-8 cysteine residues and several intramolecular disulfide bonds which provide them with a high stability against protease degradation, high temperature and within a broad pH range. The tertiary structure of these proteins is very similar to the β-defensins, it contains five antiparallel β-sheets connected by three loops. In spite of the fact that they are very different in their amino acid sequences; conserved homologous regions can be identified. Based on it they can be divided into two main groups: peptides which contain the Penicillium chrysogenum antifungal protein (PAF) cluster in their amino acid sequences, and peptides with Penicillium brevicompactum bubble protein (BP) cluster. Both of them have a potent antifungal activity, but the peptides with PAF-cluster are effective against filamentous fungi. These proteins secreted by taxonomical distinct species cause similar symptoms on the susceptible fungus, but they have different mode of action and species specificity, nevertheless, their structure is very similar. They have high stability and efficacy; their limited toxicity and low costs of production could make them suitable for use in practical respects in agricultural fields, especially in plant protection on the field and crop protection after the harvest

Potential applications of filamentous fungus derived β-defensin-like antifungal proteins in agriculture

Many filamentous fungi are postharvest and destructive plant pathogens and are thus responsible for enormous crop losses worldwide. The antifungal proteins secreted by filamentous fungi are promising agents for prevention of fungal diseases in the agriculture. The extracellular β-defensin-like antifungal proteins derived from ascomycetous filamentous fungal species are especially interesting in this respect because of their chemical and biological properties. The main features of these extracellular proteins are a low molecular mass, a basic character, and the presence of 6-8 cysteine residues and several intramolecular disulfide bonds which provide them with a high stability against protease degradation, high temperature and within a broad pH range. The tertiary structure of these proteins is very similar to the β-defensins, it contains five antiparallel β-sheets connected by three loops. In spite of the fact that they are very different in their amino acid sequences; conserved homologous regions can be identified. Based on it they can be divided into two main groups: peptides which contain the Penicillium chrysogenum antifungal protein (PAF) cluster in their amino acid sequences, and peptides with Penicillium brevicompactum bubble protein (BP) cluster. Both of them have a potent antifungal activity, but the peptides with PAF-cluster are effective against filamentous fungi. These proteins secreted by taxonomical distinct species cause similar symptoms on the susceptible fungus, but they have different mode of action and species specificity, nevertheless, their structure is very similar. They have high stability and efficacy; their limited toxicity and low costs of production could make them suitable for use in practical respects in agricultural fields, especially in plant protection on the field and crop protection after the harvest

Modification of the carotenoid production of mucor circinelloides using different xanthophyllomyces dendrorhous crts genes

Canthaxanthin and astaxanthin are oxygenated derivatives of β-carotene and have several beneficial effects on the animal and human health. They are mainly used as feed additives, especially for fishes and poultry. The aim of the present study is to examine the biological requirements for the microbial production of these natural pigments. Mucor circinelloides has been used as model organism of the microbial carotenoid biosynthesis. Previously, canthaxanthin production was achieved in this fungus by integrating a modified bacterial β-carotene-ketolase gene in the genome of M. circinelloides. In the present study, crtS genes of different X. dendrorhous strains were cloned and expressed in β-carotene producing wild type and canthaxanthin producing mutant M. circinelloides strains. X. dendrorhous is an astaxanthin producing basidiomycete yeast. Previously, it was proven, that the cythochrome-P450 hydroxylase enzyme encoded by the crtS gene has β-carotenehydroxylase activity (ÁLVAREZ et al., 2006). A hypothethical β-carotene-ketolase activity has also been suggested (OJIMA et al., 2006), but it has not been verified yet. In our study, crtS genes with different sequences were amplified and several plasmids were constructed carrying the isolated genes under the control of the regulator regions of the Mucor glyceraldehyde-3-phosphate dehydrogenase 1 gene. The plasmids were transformed into the fungal protoplasts. Analysis of the carotenoid content of the transformants revealed astaxanthin production in the resulting strains. This work has been supported by the KTIA-OTKA grant CK 80188