Preparation of a Xyloglucan Oligosaccharide Mixture from Tamarind Seed Gum and its Promotive Action on Flower Opening in Carnation Cultivars

A mixture of xyloglucan oligosaccharides (XGO) was prepared from xyloglucan (XG) of tamarind seed gum by digestion with Aspergillus recombinant XG-specific xyloglucanase and subsequent purification by ethanol fractionation. The XGO mixture contained XG7, XG8, and XG9 at the ratio of 1 : 4 : 5, which was almost identical to the literature value of constituent subunits ratio of 1.2 : 3.8 : 5. The XGO mixture at 1% promoted flower opening in carnation (Dianthus caryophyllus L.) cultivars, such as ‘Pure Red’ and ‘Lillian’. On the other hand, there was no effect on other cultivars, such as ‘Collin’, ‘Light Pink Barbara’, and ‘Mule’. Promotion of flower opening by 1% XGO was exhibited earlier than that by glucose or sucrose at 1% in ‘Pure Red’ carnation. Separate application of XG7 or XG9 stimulated flower opening in ‘Pure Red’ carnation, suggesting that all the constituents in the XGO mixture were effective in stimulating flower opening. Based on these observations, the mechanism of action of XGO on carnation flower opening and its future practical use as a flower-opening agent are discussed.