Abstract: With Dioscorea bulbifera L. microtubers, we studied the conservation in vitro at 4℃ low temperature and its transcriptome analysis. After the original data were pretreated, the effective ratio of reads in the control group(Con25) and the treatment group(Con4) was 98.67% and 98.69%, respectively. The 219792 transcripts of 200 bp(177Mb) and 161066 Unigenes(99Mb) were obtained after the removal of the splicing sequence; 10 species of the most NR annotations in the Unigene was Aureobasidium pullulans EXF-150, Vitis vinifera, Theobroma cacao, Oryza sativa Japonica Group, Amborella trichopoda, Setaria italica, Aureobasidium pullulans var. namibiae CBS 147.97, Jatropha curcas, Aureobasidium melanogenum CBS 110374 and Pestalotiopsis fici W106-1, respectively. The 5 KOG of the annotated most unigenes were general function prediction only, signal transduction mechanisms, posttranslational modification, protein turnover, chaperones, translation, ribosomal structure and biogenesis and energy production and conversion. The 5 pathway of the KEGG annotated most unigenes were carbon metabolism, biosynthesis of amino acids, glycolysis/gluconeogenesis, starch and sucrose metabolism and pyruvate metabolism. The number of annotated unigenes was 26 006, the number of different annotated enzymes was 1 177, and the number of different pathway was mapped to 327. Gene function of samples in Biological Process classification mainly gathered at cellular process and metabolic process, in Cellular Component classification it gathered at cell and cell part, in Molecular Function classification mainly concentrated in binding and catalytic activity. In conservation in vitro at low temperature of D.bulbifera L. microtubers, a total of 164 145 differentially expressed genes was obtained, of which 63305 genes were up-regulated and 100 840 genes were down regulated. Extremely significant GO terms of the differentially expressed genes were vacuole inheritance, single strand break repair, mitotic spindle elongation, maltose catabolic process, mannosyltransferase activity, mannosylphosphate transferase activity, cell wall mannoprotein biosynthetic process, G1 phase of mitotic cell cycle, incipient cellular bud site and establishment of mitotic spindle orientation. Extremely significant pathways of the differentially expressed genes were primary bile acid biosynthesis, steroid hormone biosynthesis, chlorocyclohexane and chlorobenzene degradation, bisphenol degradation, fluorobenzoate degradation, glycosaminoglycan biosynthesis-chondroitin sulfate, glycosaminoglycan biosynthesis-heparan sulfate, toluene degradation, naphthalene degradation and riboflavin metabolism. The experimental results provides a theoretical basis for germplasm conservation of D.bulbifera L. microtuber and its subsequent germination.

Key words: Dioscorea bulbifera L., microtuber, conservation in vitro at low temperature, transcriptome analysis