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Charcoal is a carbonaceous particulate matter with a highly aromatic structure produced by incomplete combustion, and it can cause persistent long-term effects on soil ecological functions. In this study, we determined soil organic carbon pools and associated enzyme activities following five years of different charcoal treatments[charcoal removal (B 0 ), charcoal retained in situ (B 1 ), and the addition of charcoal removed from B 0 (B 2 )] and the unburnt control (UB) in a recently harvested Pinus massoniana plantation subjected to broadcast burning. The results showed that dissolved organic carbon (DOC), microbial biomass carbon (MBC), coarse and fine particulate organic carbon (CPOC and FPOC), and recalcitrant carbon (RC) contents were significantly lower in B 1 than those in UB soil ( P <0.05). The MBC and FPOC contents of B 2 soil were comparable to those of UB soil, which were significantly higher than those of B 0 soil ( P <0.001). There was no difference in MBC/TC between the B 2 and UB soils, whereas MBC/TC was significantly lower in B 0 than in UB soil ( P <0.05). β -glucosidase and peroxidase activities of B 0 , B 1 , and B 2 soils were significantly lower than that of UB soil ( P <0.01), and polyphenol oxidase activity was significantly lower in B 0 and B 2 soils than in UB soil ( P <0.01). No significant difference in soil TC, DOC, readily oxidized carbon (ROC), CPOC, and RC content as well as associated enzyme activities was observed among the charcoal treatments ( P >0.05). Redundancy analysis showed that sucrose and polyphenol oxidase were the key drivers influencing soil organic carbon fractions, accounting for 16.3% and 12.7% of the total variance, respectively. Overall, our findings indicated that fire-deposited charcoal played a positive role in enhancing soil microbial biomass carbon recovery, soil organic carbon accumulation, and stability, highlighting the importance of charcoal in the management of subtropical plantations in the future.

This study aims to explore the resource utilization of used fungus-growing materials produced in the cultivation of Gastrodia elata. To be specific, based on the production practice, this study investigated the recycling mechanism of used fungus-growing materials of G. elata by Phallus inpudicus. To screen edible fungi with wide adaptability, this study examined the allelopathic effects of Armillaria mellea secretions on P. impudicus and 6 kinds of large edible fungi and the activities of enzymes related to degradation of the used fungus-growing materials of G. elata. The results showed that P. impudicus can effectively degrade cellulose, hemicellulose, and lignin in used fungus-growing materials of G. elata. The cellulase activity of A. mellea was significantly higher than that of P. impudicus, and the activities of lignin peroxidase, polyphenol oxidase, and xylanase of P. impudicus were significantly higher than those of A. mellea, which was the important reason why A. mellea and P. impudicus used different parts and components of the used fungus-growing materials to absorb carbon sources and develop ecological niche differences. The growth of P. impudicus was significantly inhibited on the used fungus-growing materials of G. elata. The secretions of A. mellea had allelopathic effects on P. impudicus and other edible fungi, and the allelopathic effects were related to the concentration of allelopathy substances. The screening result showed that the growth and development of L. edodes and A. auricular were not significantly affected by 30% of A. mellea liquid, indicating that they had high resistance to the allelopathy of A. mellea. The results showed that the activities of extracellular lignin peroxidase, polyphenol oxidase, and xylanase of the two edible fungi were similar to those of P. impudicus, and the cellulase activity was higher than that of P. impudicus. This experiment can be further verified by small-scale production tests.

There is no consensus on the content, accumulation, transformation and content determination methods of phenolic acids in fresh Salvia miltiorrhiza. In order to find out the true content of phenolic acids in fresh S. miltiorrhiza, a variety of treatment me-thods were used in this study to prepare sample solution. The content changes of phenolic acids in S. miltiorrhiza samples with different dehydration rates were investigated during drying and shade drying processes. Polyphenol oxidase(PPO) of S. miltiorrhiza was extracted and purified by ammonium sulfate precipitation and dialysis to investigate the enzymatic properties. The content of rosmarinic acid, lithosperic acid and S. nolic acid B in S. miltiorrhiza was determined by UPLC. The results showed that the content of phenolic acids in fresh S. miltiorrhiza was highest when it was homogenized with 1 mol·L~(-1) HCl solution or 1 mol·L~(-1) HCl methanol solution. There was no significant difference in the content of phenolic acids in S. miltiorrhiza with different dehydration rates, indicating that there was no correlation between phenolic acid content and dehydration rate. The optimum pH of S. miltiorrhiza PPO was 7.6 and the optimum temperature was 40 ℃. With catechol as substrate, S. miltiorrhiza PPO had the enzymatic browning reaction which was in compliance with Michaelis equation, with Michaelis constant K&#95;m of 0.12 mol·L~(-1) and V&#95;(max) of 588.23 U·min~(-1). The inhibitory effect of citric acid, disodium ethylenediamine tetraacetate, ascorbic acid and sodium sulfite on S. miltiorrhiza PPO increased with the increase of inhibitor concentration, and sodium sulfite showed the strongest inhibitory effect. The present study proved that there were a large number of phenolic acids in fresh S. miltiorrhiza, which were the secondary metabolite of primitive accumulation during the growth of S. miltiorrhiza, rather than the induced product of postharvest drying and dehydration stress. This study has reference value and significance for the cultivation, harvest and processing of S. miltiorrhiza.

Polyphenol oxidase(PPO) is an important antioxidant enzyme in plants. It has the functions of scavenging active oxygen and synthesizing phenols, lignin, and plant protection factors, and can enhance the plant's resistance to stress and resistance to pests and diseases. Our previous research found that Salvia miltiorrhiza PPO gene can positively regulate salvianolic acid B synthesis. In order to further explore the mechanism, a pGBKT7-PPO bait vector was constructed using the cloned S. miltiorrhiza polyphenol oxidase gene(SmPPO, GenBank accession number: KF712274.1), and verified that it had no self-activation and no toxicity. The titer of S. miltiorrhiza cDNA library constructed by our laboratory was 4.75 × 107 cfu·mL~(-1), which met the requirements for library construction. Through yeast two-hybrid test, 22 proteins that could interact with SmPPO were screened. Only yeast PAL1 and TAT interacted with SmPPO through yeast co-transformation verification. Further verification was performed by bimolecular fluorescence complementary detection(BiFC). Only TAT and SmPPO interacted, so it meant that TAT and SmPPO interacted. TAT and SmPPO were truncated according to the domain, respectively. The first 126 amino acids of SmPPO and tyrosine amino transferase(TAT) were obtained to interact on the cell membrane and chloroplast. SmPPO was obtained by subcellular localization test, which was mainly loca-lized on the nucleus and cell membrane; TAT was localized on the cell membrane. Real-time quantitative PCR results showed that the SmPPO gene was mainly expressed in roots and stems; the TAT gene was expressed in roots, and the expression level in stems and flowers was low. This article lays a solid foundation for the in-depth study of the molecular mechanism of the interaction of S. miltiorrhiza SmPPO and TAT to regulate the synthesis of phenolic substances.

To understand the effects of climate warming on rhizosphere ecological processes in the alpine scrub ecosystem, the responses of polyphenoloxidase and catalase activities in the rhizosphere and bulk soils to experimental warming (1.3 ℃) were examined during the growing season in a Sibiraea angustata scrub ecosystem on the eastern Qinghai-Tibetan Plateau, China. The results showed that the activities of polyphenoloxidase in rhizosphere and bulk soils in the middle growing season were significantly higher than those in the early or late growing season. The activities of catalase in the bulk soil increased gradually during the growing season, while they showed no seasonal changes in the rhizosphere soil. In the bulk soil, warming significantly increased the activity of polyphenoloxidase by 17.5% in the late growing season and increased that of catalase by 2.2% in the middle growing season, whereas it did not affect soil enzyme activities in early or late growing seasons. In the rhizosphere soil, warming only significantly increased the activities of polyphenoloxidase and catalase by 6.5% and 1.3% in the early growing season. The rhizosphere effect of soil polyphenoloxidase activity was positive throughout the growing season, while there was no obvious rhizosphere effect for soil catalase activity. Furthermore, warming significantly decreased the rhizosphere effect of soil polyphenoloxidase activity by 15.2% during the late growing season. These results indicated that the activities of polyphenoloxidase and catalase activities differed between rhizosphere and bulk soils, with consequences on the rhizosphere soil ecological processes under climate warming in the alpine scrub ecosystem on the eastern Qinghai-Tibetan Plateau.

The chrysanthemum black spot caused by Alternaria alternata significantly reduced the quality and yield of chrysanthemum. The crude toxin secreted by A. alternata in the metabolic process have elopathic effects on plants, which is the main pathogenic factor for the occurrence of chrysanthemum black spot. The pathogenic fungi A. alternate was isolated from chrysanthemum black spot leaves, The effects of crude toxin on plant height, stem diameter, root length, resistant material content, membrane relative permeability, polyphenol oxidase (PPO), peroxidase (POD), phenylalanine ammonia-lyase (PAL) in different treatments of chrysanthemum 'Jinba' seedlings were investigated. The results showed that the crude toxin of A. alternata had an inhibition effect on plant height, stem diameter and root length. The toxin concentration was positively correlated with the inhibitory effect. 14 days after crude toxin treatment, plant height, stem diameter and root length were significantly inhibited, with an reduction of 28.9%, 21.4% and 23.3%, respectively. The cell membrane permeability of leaf increased with the toxin concentration. Under the same toxin concentration, the cell membrane permeability first increased and then decreased with the treatment duration. The contents of soluble protein, malondialdehyde (MDA) and proline in leaves were significantly increased after treatment with the toxin solution. The increases of PAL, POD and PPO were the most significant in 10 times A. alternatacrude toxin treatment. The pathogenicity of A. alternate crude toxin to the chrysanthemum 'Jinba' seedlings was mainly through inhibi-ting the normal growth of roots and stems, destructing the root cell membrane permeability and increasing the contents of MDA, normal soluble sugar and proline, and promoting the activities of PAL, POD, PPO in leaf tissues.

The secondary structure of the mushroom polyphenoloxidase treated by the high hydrostatic pressure (HHP) was analyzed by the synchrotron radiation circular dichroism (SRCD) and Fourier transform infrared spectroscopy (FTIR). The alpha-helix content of mushroom PPO was decreased after HHP treatment, which indicated that the secondary structure of PPO was changed. There was a discrepancy of the result of the secondary structure content between untreated or HHP-treated mushroom PPO analyzed by SRCD and FTIR spectra, and this discrepancy may be due to the different determination temperature, the concentration of the PPO solution and the spectra analysis method etc. The fluorescence spectra showed that the fluorescence intensity of the mushroom PPO was decreased after HHP treatment, and a red shift was observed after HHP treatment, which indicated that the tertiary structure of the enzyme molecule has been modified.