Energy status regulated umami compound metabolism in harvested shiitake mushrooms(Lentinus edodes)with spores triggered to release

The molecular mechanisms of energy status related to the umami taste of postharvest shiitake mushrooms during spore release remain poorly understood.In this study,the variations of energy status and umami taste of mushrooms were measured at 25℃.At 24 h storage,slight spore prints of mushrooms were first pictured,respiration peaked.Significant ATP decrease and ADP increase were also observed as the initiation of postharvest senescence(P<0.05).Meanwhile,the activities of phosphohexose isomerase,succinate dehydrogenase,glucose-6-phosphate dehydrogenase and cytochrome c oxidase and the contents of umami nucleotides and amino acids were maintained at higher levels in mushrooms with spore release.Notably,the equivalent umami concentration(EUC)was strongly correlated with energy levels(R=0.80).Fifteen related gene expression levels in the energy metabolism pathway were downregulated.LecpdP1 and LeAK were significantly expressed in the conversion of ATP into AMP and played key roles in connecting the energy state and umami level.These results provided valuable insights on the umami taste associated with energy metabolism mechanism during postharvest mushroom spore release.

Effects of polyamines on the early development of cystocarps,spore release,survival,and germination rate of Gracilariopsis lemaneiformis

Three polyamines(PAs)(spermidine(Spd),spermine(Spm),and putrescine(Put))were used as growth regulators to the marine macroalgae Gracilariopsis lemaneiformis and to female gametophyte and reproductive tissues(cystocarps were constructed),which led to early maturation of cystocarps and spore release.Laboratory cultivation revealed that exogenous PA application accelerated the development of cystocarps,and the mean sporeling growth rate was 20%–50%/d during the initial week of cultivation.The spore count(SC),survival rate(SR),and germination rate(GR)of G.lemaneiformis showed different responses to PA(10-6 mol/L and 10-3 mol/L)treatments under different temperatures(18,26,and 34℃),light intensities(30,60,and 90μmol photons/(m^(2)·s)),salinities(25,30,and 35),and nutrient levels(25꞉2.5,50꞉5.0,and 75꞉7.5μmol/L NH4Cl꞉K2HPO4),and the optimal conditions were 26℃,light intensity of 60μmol/(m^(2)·s),salinity of 35,and nutrient level of 50꞉5.0μmol/L NH4Cl꞉K2HPO4.Under the optimum conditions,the SC per cystocarp increased by 82.38%,and the spore SR and GR increased by 33.07%and 46.44%,respectively.Each experiment lasted for 7 days,with the highest SC on Day 4 and plateauing on Day 7.The results indicate that PAs could promote the early maturation,spore release,survival,and germination of G.lemaneiformis under laboratory conditions.