Cryogenic autolysis is a typical phenomenon of abnormal metabolism in Volvariella volvacea. Recent studies have identified 20 significantly upregulated genes via high-throughput sequencing of the mRNAs expressed in the mycelia of V. volvacea after cold exposure. Among these significantly upregulated genes, 15 annotated genes were used for functional annotation cluster analysis. Our results showed that the cyclin-like F-box domain (FBDC) formed the functional cluster with the lowest P-value. We also observed a significant expansion of FBDC families in V. volvacea. Among these, the FBDC3 family displayed the maximal gene expansion in V. volvacea. Gene expression profiling analysis revealed only one FBDC gene in V. volvacea (FBDV1) that was significantly up-regulated, which is located in the FBDC3 family. Comparative genomics analysis revealed the homologous sequences of FBDV1 with high similarity were clustered on the same scaffold. However, FBDV1 was located far from these clusters, indicating the divergence of duplicated genes. Relative time estimation and rate test provided evidence for the divergence of FBDV1 after recent duplications. Real-time RT-PCR analysis confirmed that the expression of the FBDV1 was significantly up-regulated (P , 0.001) after cold-treatment of V. volvacea for 4 h. These observations suggest that the FBDV1 is involved in the cryogenic autolysis of V. volvacea.
Available at: http://works.bepress.com/qiuming-zhu/6/