Expression profiling of laccase and ß-glucan synthase genes in Pleurotus ostreatus during different developmental stages.

BACKGROUND: Pleurotus ostreatus, commonly known as the oyster mushroom, is a saprophytic fungus with many applications in biotechnology and medicine. This mushroom is a rich source of proteins, polysaccharides, and bioactive compounds that have been shown to possess anticancer, antioxidant, and immunomodulatory properties. In this study, we investigated the expression profile of laccase (POXA3) and ß-glucan synthase (FKS) genes during different developmental stages in two strains of P. ostreatus. METHODS AND RESULTS: Cultural and morphological studies of the two strains were studied. DMR P115 strain recorded faster mycelial growth compared to the HUC strain. However, both strains produced white, thick fluffy mycelial growth with radiating margin. Morphological characteristics of the mushroom fruiting body were also higher in the DMR P115 strain. The expression of these genes was analyzed using quantitative real-time PCR (qPCR) and the results were compared to those of the reference gene ß-actin. The expression of laccase (POXA3) was higher in the mycelial stage of DMR P115 and HUC strains indicating its role in the fruiting body development and substrate degradation. The expression of ß-glucan synthase (FKS) was upregulated in the mycelium and mature fruiting body of the DMR P115 strain. In contrast, there was only significant upregulation in the mycelial stage of the HUC strain, which indicates its role in cell wall formation and the immunostimulatory properties of that strain. CONCLUSION: The results deepen the understanding of the molecular mechanism of the fruiting body development in P. ostreatus and can be used as a foundation for future lines of research related to strain improvement of P. ostreatus.

Silver nanoparticles green synthesized with leaf extract of disease-resistant amaranthus genotypes effectively suppress leaf blight (Rhizoctonia solani Kühn) disease in a susceptible red amaranthus cultivar.

Silver nanoparticles (AgNPs) were green synthesized using leaf extract of the leaf blight disease (Rhizoctonia solani) susceptible red amaranthus (Amaranthus tricolor L.) and the disease-resistant green (A. dubius) and the wild amaranthus (A. viridis) genotypes, physically characterized, and assessed for their anti-fungal effects against R. solani. The green synthesized nanostructures showed an absorption maximum typical of silver nanoparticles in spectroscopy, and face-centered cubic structures in X-ray diffraction. Field Emission Scanning Electron Microscopic analysis and High-Resolution Transmission Electron Microscopy revealed the size range to be 35-45 nm for all the samples. In vitro mycelial growth inhibition of the pathogen occurred with 500 and 750 ppm concentrations of the nanoparticles in a poisoned-food assay. Further, detached leaves of red amaranthus variety were sprayed with the nanoparticles, and then challenged with the pathogen. There was significant difference in lesion development on leaves sprayed with Ad-AgNPs and Av-AgNPs compared to those treated with At-AgNPs. In the in vivo assay, challenging with the pathogen after spraying the foliage of the leaf blight susceptible red amaranthus variety with Ad-AgNPs at 750 ppm concentration recorded the lowest disease index (7.40) followed by that received Av-AgNPs spray at the same concentration (17.69), five days after inoculation. At-AgNPs treated plants had a disease index of 49.38. Our findings suggest that application of AgNPs green synthesized with leaf extract of disease-resistant genotypes of amaranthus effectively suppressed leaf blight disease incidence in a susceptible amaranthus genotype. To our knowledge, this is the first report on the improved plant pathogen-suppressive activity of any metal nanoparticle when biogenically synthesized using extracts from a disease-resistant plant genotype.

Development of improved strain in species of Pleurotus by gamma irradiation.

The oyster mushroom (Pleurotus spp.) is the second important edible mushroom in the world, with 19 per cent contribution to total mushroom production (Sharma et al., Mushroom Res 26(2):111-120, 2017). The cultivated mushrooms face the problems like loss of genetic diversity and strain degeneration (Wang et al., Curr Microbiol 65(4):424-431, 2012). Thus to enhance the productivity within short duration, three species of Pleurotus namely Pleurotus djamor, Pleurotus florida and Pleurotus ostreatus were gamma irradiated at 20 and 25 Gy at 9.779 kGy/h and performance of mutants followed by three generation of selection in paddy straw substrate were observed. Biological efficiency (BE) of P. djamor mutants irradiated at 20 Gy was increased by 9.25 per cent. The number of days taken for primordial initiation was also reduced by 1 day compared to P. djamor. P. florida irradiated at 25 Gy recorded increase in sporocarp size over P. florida. The biological efficiency of P. ostreatus irradiated at 25 Gy was improved by 12.89 per cent and there was earliness in primordial initiation by 3 days compared to P. ostreatus. The polymorphism per cent was analysed by Random Amplified Polymorphic DNA (RAPD) and revealed that P. djamor, P. florida and P. ostreatus had 16.70%, 25% and 22% polymorphism with their respective improved strains.