The Degeneration Of Volvariella Volvacea Spawn Preservation By Mycelium Subculture

Volvariella volvacea (Bull.:Fr.) Sing is a kind of nourishing and delicious mushroom, it is ranked the fifth most important edible mushroom in the world in terms of yield. Due to its cellulolytic characteristics, V. volvacea has been extensively cultivated on an array of agricultural residues under artificial conditions. However, V. volvacea is a typical high temperature type edible mushroom with weak low temperature tolerance. Mycelia subculture can result in spawn degradation of V. volvacea, which cause yield reduction and serious economic loss. The paper aims to research the degeneration of spawn presenting in passage. Finally the enzymatic mRNA levels were analyzed to conduct a preliminary study of molecular mechanism. The results were concluded as follows.(1) In order to investigate the effects of different points of PDA (inside, middle and outside) and different times of mycelia subculture, two strains named V971 and V28 of V. volvacea, which widely used in corp production, were chosen as the experiment objective. A degenerated spawn was collected at test tube slant in two month, and 9 spawns were saved in 18 month. The liquid spawns were named MO, first degenerated spawns were named M1, and so on. All of the spawns should passage once in 2-3 month by mycelia subculture.The growth rate of mycelia increased obviously with passage times and decreased subsequently. The aerial mycelia density, spore yields, and biomass become fewer along with the passage. The above indexes showed a trend that “outside>middle>inside”.(2) The nutrition experiment results showed that polysaccharide, flavonoids, proteins, polyphenols, amino acides content and the enrichment ability for mineral elements of the all the strains declines continuously with the passage. The enrichment ability of three points of spawn showed a trend that "outside> middle > inside", and other nutritions was not a rule can be followed with the passage.(3) The enzymic experiment results showed that FPase, CMCase, PPO, laccase, and cellase activity of all the strains decreased with the increase of time of subculture. At the early degenerated period, the enzymes showed a trend that "outside> middle> inside", after no obvious regularity.(4) The mRNA levels of P-glucosidase and lac-1 were analyzed to conduct a preliminary study of molecular mechanism about strains degeneration. The results showed that the expression of two enzymes were decline with the passage.