In Volvariella volvacea, a species of edible mushroom, cryogenic autolysis is a typical part of abnormal metabolism. Previous functional annotation cluster analyses of cold-induced gene expression profiles have shown that the ubiquitin-conjugating enzyme E2 (UBE2) and the cyclin-like F-box domain (FBDC) form the functional clusters. Among them, a specific FBDC gene has been found to be in response to cold stress and correlated with the cryogenic autolysis of V. volvacea. In this study, analysis of gene expression profiling showed that only one type of UBE2 in V. volvacea (UBEV2) was significantly up-regulated. Further quantitative real-time PCR analysis confirmed that the expression of UBEV2 was significantly up-regulated (P < 0.05) after cold-treatment lasting 4, 6, and 8 h. Western-bolt analyses confirmed that the protein expression of UBEV2 was in response to cold stress. This provided evidence that UBEV2 was a cold stress-responsive gene and closely correlated with cryogenic autolysis. The specific distribution of UBEV2 in recently diverged herb decay fungi indicated that UBEV2 was not evolutionarily correlated with early diverging fungi. Phylogenetic analysis indicated that UBEV2 was generated by horizontal gene transfer (HGT) from the ancestry of Selaginella moellendorffii UBE2. Further relative time estimation and detection of natural selection showed that there has been recent positive selection after HGT in UBEV2. Molecular modeling and logo analysis showed that the cysteine-cysteine motif is the characteristic of the UBEV2 family. These observations indicate that UBEV2 and FBDV1 are the newly discovered cold stress-responsive genes correlated with the cryogenic autolysis of V. volvacea.

Related research on artificial cultivation of the edible fungi in modern China can be traced back to 100 years ago. The earliest article about the cultivation techniques of the edible fungi was published in 1897 on Agricultural Study Newspaper sponsored by Shanghai Agricultural Society. From the late 1800s to 1940s, the elder generation of scholars including Zou Bingwen, Hu Changzhi, Pan Zhinong, Li Shiyi, Sun Yunwei, and Yu Xiaotie, etc. not only introduced many foreign techniques in edible fungi cultivation a nd disseminated scientific knowledge and cultivation techniques, but also held various edible fungi talents training courses, set up experimental bases, and conduct edible fungi cultivation experiments. Those have laid a preliminary foundation for the modernization of China’s edible fungi cultivation techniques. After the founding of the PRC, the edible fungi cultivation industry has gained more space for development, and has achieved many milestone achievements, mainly including the tremella artificial cultivation technique, the hedgehog hydnum artificial cultivation technique, the Xianggu artificial cultivation with crushed-wood material technique, the white mushroom fine breed selection and breeding and cultivation technique improvement, the black fungus cultivation with crushed-wood material and fine breed selection and breeding, and the golden needle mushroom find breed selection and year-round cultivation technique innovation, as well as the acclimatization of wild edible fungi and the development of new varieties of edible fungi. These inventions and innovations have provided solid technical support to the development of the edible fungi industry in China. The reform and opening-up starting 1978 has provided a favorable policy environment for the development of the edible fungi industry in China. In the period of more than 30 years thereafter, the edible fungi industry in China has been developing rapidly, with the annual yield rocketing from 60,000 tons in 1978 to 20.2 million tons in 2009, and the proportion of the yield against total world yield growing from 5% in the past to more than 70% at present. During this historical period, many research institutions and scientific research staffs have made important contributions to the development of the edible fungi industry in China. Among them, the most important achievements are made by Researcher Chen Meipeng from the Institute of Edible Fungi of Shanghai Academy of Agricultural Sciences, Professor Yang Xinmei from Huazhong Agricultural University, Researcher Huang Nianlai from Fujian Sanming Mycological Institute, and Professor Zhang Shuting from Chinese University of Hong Kong. When we look back, we treasure the outstanding achievements made by the elder generation of scholars on the development of the edible fungi industry in China. When we look into the future, we are geared with enthusiasm and confidence, and we will work hard to achieve higher in the edible fungi industry in China.