LbSakA-mediated phosphorylation of the scaffolding protein LbNoxR in the ectomycorrhizal basidiomycete Laccaria bicolor regulates NADPH oxidase activity, ROS accumulation and symbiosis development.

Ectomycorrhizal symbiosis, which involves mutually beneficial interactions between soil fungi and tree roots, is essential for promoting tree growth. To establish this symbiotic relationship, fungal symbionts must initiate and sustain mutualistic interactions with host plants while avoiding host defense responses. This study investigated the role of reactive oxygen species (ROS) generated by fungal NADPH oxidase (Nox) in the development of Laccaria bicolor/Populus tremula × alba symbiosis. Our findings revealed that L. bicolor LbNox expression was significantly higher in ectomycorrhizal roots than in free-living mycelia. RNAi was used to silence LbNox, which resulted in decreased ROS signaling, limited formation of the Hartig net, and a lower mycorrhizal formation rate. Using Y2H library screening, BiFC and Co-IP, we demonstrated an interaction between the mitogen-activated protein kinase LbSakA and LbNoxR. LbSakA-mediated phosphorylation of LbNoxR at T409, T477 and T480 positively modulates LbNox activity, ROS accumulation and upregulation of symbiosis-related genes involved in dampening host defense reactions. These results demonstrate that regulation of fungal ROS metabolism is critical for maintaining the mutualistic interaction between L. bicolor and P. tremula × alba. Our findings also highlight a novel and complex regulatory mechanism governing the development of symbiosis, involving both transcriptional and posttranslational regulation of gene networks.

Performance of two egg parasitoids of brown marmorated stink bug before and after cold storage.

Introduction: The genus Trissolcus includes a number of egg parasitoids that are known to contribute to the control of Halyomorpha halys. The number of progenies, particularly females, is important for the efficient mass rearing of species used in augmentative biological control programs. Cold storage is an important technique for extending the shelf life of natural enemies used in such programs. Methods: We assessed how fecundity, sex ratio, lifespan, and the number of hosts parasitized within 24 h were affected by host density for T. japonicus and T. cultratus when offered fresh H. halys eggs and how these parameters were affected if adult parasitoids were first placed in cold storage (11°C in the dark) for 19 weeks before being used for propagation. Results: The fecundity were 110.2 and 84.2 offspring emerged at 25°C, for parasitoids not placed in cold storage; among the offspring that emerged, 82.6% and 85.6% were female for T. japonicus and T. cultratus, respectively. If first placed in cold storage, T. japonicus and T. cultratus produced 35.1 and 24.6 offspring per female, respectively, although cold storage significantly extended the shelf life. The survival rates of parasitoids that were placed in cold storage were 90.3% and 81.3% for females, and 3.2% and 0.9% for males of T. japonicus and T. cultratus, respectively. The number of hosts parasitized within 24 h was not shown to be density dependent, but it was significantly lower after cold storage. Discussion: This information can be used to estimate the likely production for augmented rearing colonies for use in biological control programs.

GlPP2C1 Silencing Increases the Content of Ganodermalingzhi Polysaccharide (GL-PS) and Enhances Slt2 Phosphorylation.

Polysaccharides have attracted much attention in the food industry due to their diverse biological activities. To date, research on the mechanism of polysaccharide synthesis has mainly focused on the role of crucial enzymes in the polysaccharide synthesis pathway, but other genes that regulate polysaccharide synthesis have not been well explored. In this study, the GlPP2C1 gene, encoding a phosphoprotein type 2C phosphatase, was cloned, and PP2C-silenced strains (PP2C1i-1 and PP2C1i-3) were screened. Measurements of the polysaccharide content and cell wall tolerance revealed that GlPP2C1 silencing increased the polysaccharide content and enhanced cell wall resistance in Ganoderma lingzhi. The contents of intracellular polysaccharides (IPS), extracellular polysaccharides (EPS) and ß-1,3-D-glucan in PP2C-silenced strains were increased by 25%, 33% and 36%, respectively, compared with those in the WT strains and strains transformed with an empty vector. Further mechanistic studies showed that GlPP2C1 silencing increased the content of Ganoderma lingzhi polysaccharides (GL-PS) through Slt2. In summary, this study revealed the mechanism through which protein phosphatase regulates GL-PS biosynthesis for the first time.

[Effects of Nano-membrane on Aerobic Composting Process and Odor Emission of Livestock Manure].

Aerobic composting is an important approach to treat livestock manure; however, traditional composting has some problems, such as low efficiency, or odorous pollution. In order to speed up the composting process and reduce malodorous gas emissions, this study explored the mechanism of nano-membrane for improving the efficiency of livestock manure composting. A trough aerobic composting experiment was set up to evaluate the physicochemical properties, enzyme activities, and emission of odorous gases. The results showed that covering with nano-membrane could accelerate the temperature rise; reduce the pH, organic matter(OM), and ammonia nitrogen(NH4+-N); increase electrical conductivity(EC); enhance the activities of urease, protease, cellulase, xylanase, and peroxidase; while the total cumulative emissions of NH3, H2S, and TVOC were reduced by 58%, 100%, and 61%, respectively. The correlation analysis showed that most enzyme activities were easily affected by temperature(T), EC, OM, and C/N. The emission rate of NH3 was positively correlated with T and negatively correlated with pH, and TVOC was significantly correlated with various physicochemical properties. This experiment showed that covering nano-membrane could accelerate the compost maturity and reduce the emission of odorous gases. This approach has no health risks and produces low malodorous gas, which may effectively solve the problem of pollutant emission caused by livestock manure compost fermentation, promoting the green and sustainable development of the breeding industry. In addition, it facilitates livestock manure fertilizer application, and provides technical support for the development of resource utilization of biomass waste.