Cell wall enzymes and changes in sugar content in pollinated orchids treated with ethylene inhibitors and sugars

The pollinated flowers of Dendrobium Pompadour orchids exhibited rapid morphological changes, which resulted in full flower closure. In contrast, unpollinated flowers remained fresh and turgid during the identical time period. The aim of this study was to examine the pollination-induced changes in the cell wall enzyme activity and sugar content. Cell wall hydrolase assays showed that pollination induces significant increases in polygalacturonase, pectate lyase and cellulase activity, whereas pectin methyl esterase showed insignificant changes in activity. Membrane leakage was rapid in pollinated flowers. The total and reducing sugar content increased in the pollinated flowers and was most profound in the column of the flowers. Treatment with ethylene inhibitors and sugars suppressed cell wall hydrolase activity and membrane leakage to a varying extent. The sugar content was more stable in the treated flowers. Altogether, the results show that ethylene inhibitors effectively delay pollination-induced floral destruction.