Novel umami peptides from two Termitomyces mushrooms and molecular docking to the taste receptor T1R1/T1R3

Wild edible Termitomyces mushrooms are popular in Southwest China and umami is important flavor qualities of edible mushrooms.This study aimed to understand the umami taste of Termitomyces intermedius and Termitomyces aff.bulborhizus.Ten umami peptides from aqueous extracts were separated using a Sephadex G-15 gel filtration chromatography.The intense umami fraction was evaluated by both sensory evaluation and electronic tongue.They were identified as KLNDAQAPK,DSTDEKFLR,VGKGAHLSGEH,MLKKKKLA,SLGFGGPPGY,TVATFSSSTKPDD,AMDDDEADLLLLAM,VEDEDEKPKEK,SPEEKKEEET and PEGADKPNK.Seven peptides,except VEDEDEKPKEK,SPEEKKEEET and PEGADKPNK were selectively synthesized to verify their taste characteristics.All these 10 peptides had umami or salt taste.The 10 peptides were conducted by molecular docking to study their interaction with identified peptides and the umami taste receptor T1R1/T1R3.All these 10 peptides perfectly docked the active residues in the T1R3 subunit.Our results provide theoretical basis for the umami taste and address the umami mechanism of two wild edible Termitomyces mushrooms.

Aroma profile of two commercial truffle species from Yunnan and Sichuan,China:inter-and intraspecific variability and shared key compounds

Aroma is central to the worldwide success of truffles as gourmet food and the high prices paid for these edible mushrooms.In this study,volatile organic compounds(VOCs)from fruiting bodies of two Chinese truffles of commercial relevance,Tuber indicum and Tuber pseudohimalayense,were analyzed using headspace solid-phase microextraction(HS-SPME)coupled with gas chromatography-mass spectrometry(GC-MS).We aimed to characterize the aroma profile and determine whether it would be influenced by provenance and stage of maturation.We thus collected and analyzed young,middle mature and mature fruiting bodies of each species from different locations in Yunnan and Sichuan provinces,located in southwestern China.Overall,76 VOCs were identified,belonging to different chemical classes,i.e.alcohols and phenols,aldehydes and ketones,benzenes and methoxy compounds,hydrocarbons and amines.A large number of volatiles identified in T.indicum and T.pseudohimalayense are reported here for the first time for these truffles.While more than 50%of identified VOCs were produced by both truffle species,considerable differences were present in the aroma profiles of fruiting bodies collected at various maturation stages,revealing a dynamic pattern in the biosynthesis of VOCs.Furthermore,truffles of different provenance had distinct proportions of volatile constituents,suggesting that,besides genetic factors,edaphic and microclimatic conditions influence the synthesis of VOCs in a complex manner.

Non-host plants:Are they mycorrhizal networks players?

Common mycorrhizal networks(CMNs)that connect individual plants of the same or different species together play important roles in nutrient and signal transportation,and plant community organization.However,about 10%of land plants are non-mycorrhizal species with roots that do not form any wellrecognized types of mycorrhizas;and each mycorrhizal fungus can only colonize a limited number of plant species,resulting in numerous non-host plants that could not establish typical mycorrhizal symbiosis with a specific mycorrhizal fungus.If and how non-mycorrhizal or non-host plants are able to involve in CMNs remains unclear.Here we summarize studies focusing on mycorrhizal-mediated host and non-host plant interaction.Evidence has showed that some host-supported both arbuscular mycorrhizal(AM)and ectomycorrhizal(EM)hyphae can access to non-host plant roots without forming typical mycorrhizal structures,while such non-typical mycorrhizal colonization often inhibits the growth but enhances the induced system resistance of non-host plants.Meanwhile,the host growth is also differentially affected,depending on plant and fungi species.Molecular analyses suggested that the AMF colonization to non-hosts is different from pathogenic and endophytic fungi colonization,and the hyphae in non-host roots may be alive and have some unknown functions.Thus we propose that non-host plants are also important CMNs players.Using non-mycorrhizal model species Arabidopsis,tripartite culture system and new technologies such as nanoscale secondary ion mass spectrometry and multiomics,to study nutrient and signal transportation between host and non-host plants via CMNs may provide new insights into the mechanisms underlying benefits of intercropping and agro-forestry systems,as well as plant community establishment and stability.

Contribution to Confirmed &Synthesized on Mycorrhizae of <i>Tuber indicum</i>s.l. with Two Dominated &Subalpine Broadleaf Trees in Southwestern China

The ascomata and mycorrhizae of Tuber indicum s.l. were collected under the forest of broad-leaf species Populus yunnanensis and Quercus pannosa in the field respectively. The symbiotic relationships of both trees with T. indicum were examined and affirmed based on morphology and ITS-rDNA sequences. These two mycorrhizal combinations were successfully produced on artificially controlled substrates and cultural condition. This is the first report of a mycorrhizal association and synthesis between Chinese black truffles and poplars. A hyphal net covering the mantle’s surface of the mycorrhizae was detected in both mycorrhizal combinations. The mycorrhizal colonization of P. yunnanensis and Q. pannosa suggests that T. indicum s.l. has a broader host range and that additional corresponding wood species would be used as candidates for the cultivation of T. indicum. The nuclear-ITS sequences of the mycorrhizae included in the phylogeny of the T. indicum complex revealed that the two clades within the complex do not markedly differ with respect to their preferences for host species or geographical origin. Our results help to explain the wide distribution of both clades of the T. indicum complex. It would be more important for truffle conservation and Chinese black truffle plantation development with these two dominated & alpestrine Populus yunnanensis and Quercus pannosa at subalpine limestone areas in China.

Design, synthesis, and fungicidal activity of novel 1,3,4-oxadiazole derivatives

Employing the intermediate derivatization method(IDM), twenty novel 1,3,4-oxadiazole derivatives containing arylpyrazoloxyl moiety were designed and synthesized. The structures of the title compounds were identified by1 H NMR,13 C NMR, MS and elemental analyses, compound 4 was further identified by single-crystal X-ray diffraction. Antifungal activities against rice sheath blight(RSB) and sorghum anthracnose(SA) were evaluated by the mycelium linear growth rate method. Compounds 4, 16 and 20 displayed significant activities against RSB(EC_(50)= 0.88 mg/L, 0.91 mg/L and 0.85 mg/L, respectively),higher than the reference tebuconazole; While compound 3 exhibited higher activity against SA(EC_(50)= 1.03 mg/L), equal to commercial pyraclostrobin(EC_(50)= 1.06 mg/L). The study showed that compound 20 is a promising fungicide for further development.

Land rehabilitation improves edaphic conditions and increases soil microbial biomass and abundance

Rehabilitation of farmland improves the local eco-environmental conditions.But to what extent this transformation influences soil microbial properties is less known.In our study we compared variations in soil microbial attributes following changes in land-use types to understand the influence of altered soil properties on microbial biomass and their community structure using chloroform fumigation extraction method and phospholipid fatty acid(PLFA)analysis.For this purpose,3 agricultural(AL)(farmland,apple orchard and 2 years abandoned land)and 4 rehabilitated lands(RL)of various vegetations grassland,shrubland,mixed forest(Amorpha fruticosa and Pinus tabuliformis Carr.)and forest(Robinia pseudoacacia)were selected.Our results showed higher soil organic carbon(SOC)contents in RL soils(forest>mixed forest>grassland>shrub land)than that in AL soils.In RL soils,soil microbial biomass and abundance of group specific PLFA were significantly higher than those in AL soils.Under different land-use types,microbial community was bacteria dominated over fungi.The microbial physiological indices(G^(+)/G^(-),cyc/prec and S/M)indicated decreased environmental stress in RL soils in comparison with AL soils.In loess soils,SOC and total N correlated positively(p<0.05)with microbial biomass C,N and P and also with fungal and bacterial PLFA,indicating a positive microbial mediation in improving soil fertility.Taking together,our findings suggest that land rehabilitation,especially Robinia pseudoacacia planation,improves overall edaphic conditions and accelerates soil microbial biomass accumulation in local regions.