Molecular cloning of senescence-ssociated genes in Oncidium cut flower

The cut flower of Oncidium Gower Ramsey is one of the most important export flowers in Taiwan. After Oncidium flowers are harvested, the operation of classification and package of flowers always results in the dislodgment of pollinia cap. Consequently, ethylene is produced from flowers within hours, and the senescence of flowers is stimulated. Even the application of preservatives, the vase life of Oncidium cut flowers only increases for another 3-4 days. Therefore, it is important to find senescence-associated genes to increase the vase life of Oncidium cut flowers and delay Oncidium senescence.
In this study, mRNA differential display, suppression subtractive hybridization, and protein 2D analysis were performed to clone senescence-related cDNAs. Also, Arabidopsis oligo chip was also used to isolate up-regulated genes during Oncidium senescence. From above methods, 246 senescence-related cDNAs were further spotted on gene chip. After chip screening, 48 cDNAs were up-regulated during Oncidium senescence. Using NCBI BLAST X, 30 cDNAs were predicted to be known genes, 12 cDNAs were predicted to be Cymbidium mosaic virus, and 6 cDNAs were predicted to be unknown sequences. Eight genes of them were further identified by semi-quantitative RT-PCR, indicating they were up-regulated during Oncidium senescence. Besides, there were 6 Arabidopsis genes were up-regulated through both Arabidopsis oligo chip and Oncidium cDNA chip during Oncidium senescence. Their function in Oncidium senescence will be analysis in the future.