Study On Cold Shock Response In The Chinese Mushroom, Volvariella Volvacea

Tropical and subtropical plants exhibit a marked physiological dysfi.tnction when exposed to low or nonfreezing temperatures below I O~C. This dysfunction is referred to as chilling injury and has been of great concern for many years with harvested plant parts because lowered storage temperature are generally an effective means of extending the post-harvest life of fruits and vegetable. The phenomenon has not been well understood or recognized for its importance even though plant sensitivity to low temperature has been recorded for centuries. Volvariella volvacea (Bull.ex Fr.)Sing.. comm4mly known as the Chinese Straw Mushroom. is an important edible fungus of the tropics and subtropics. Chilling injury also has been found in this mushroom. Low temperature induced V Vol抜抋cea cell protein degradation. and result in mycelium autolyzed. Try to understand the physiological change in clod autolaysis of V i抩I~抋cea. proteinase. cold induced .protein and cold induced genes have been investigated. The results indicated: I. The mycelium of straw mushroom V23 were died after temperature donw shift from 32 0C to 40C for about 10-11 hours 2. Proteinase plays an important role during autolysis process. A proteinase consisted one peptide with molecular weight 23KD was determined by SDS- palyacrylaniide gel electrophoresis after purific~ion. and its activity change within different temperatures was also studied. The proteinase has been found high activity in the low temperature ( 40C). A cold inducible protein was found in soluble proteins of 1?volvacea mycelium during the first 2 hour of low temperature treatment. This proteln was isolated and purified by electrophorcsis technique. The isoclectric point of this protein is 6.79 and the result of SDS ?polyacrylamide gel el~trophoresis indicated that the cold inducible protein consists of t?w polypeptides with molecular weight 45.000 and 77.000 dalton respectively. 3. RNA differential display was used to investigate the cold shock gene expression. 19 random chose primers combii~d with 4 Otigo primers (Oligoj~dT)t 3A. Oligo-p(dT)1 3C. Oligo-p(dT)13G. Oligo-p(dT) 141 were amplified 78 cold-shock DNA fragments in 32 18-25 bp random chose l~U)I~ 2000 ~ II primers. 4. Seventy cold shock DNA fragments sequencing data were obtained from 70 DNA fragments cloned by T-vector. mostly DNA sequence data have not found the homological sequences in the Gene Bank. But I fragment was homology with S.scrofa tmp83.5 gene transmembrane protein: I fragements was homology with P os(reaus pox I mRNA for diphenol oxidase, Coriolus versicolor gene for laccase, Basidiomycete CECT 20197 phenoloxidase (pox3) gene. From the results of these investigate the composition change of protein and RNA after temperature down shift. it ~vas first suggested that straw mushroom autolysis is a physiological metabolism pathway of cold shock response.