Vase solutions containing sucrose result in changes to cell walls of sandersonia (Sandersonia aurantiaca) flowers

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Abstract It is well established that vase solutions containing sugar can improve the vase-life of many cut flower crops. Since cut sandersonia flowers supplied with 2% sucrose are firmer during wilting compared to water-fed controls, we have examined whether the effects of sucrose treatment extend to alterations in cell wall structure in the floral tissues, which may influence the wilting-related flower softening. Mature but not fully opened individual flowers were removed from the stems of sandersonia plants and were fed continuously with either 2% sucrose solution or water for up to 10 days. Sucrose supplementation resulted in decreased amounts of chelator-soluble pectin and increased amounts of Na2CO3-soluble pectin per individual flower, and also changed the molecular size profiles of both these pectin fractions compared to the water-fed controls. The molecular size differences were obvious after 3 days in vase solutions, and diminished with subsequent vase time. Senescence-related galactose loss was delayed in sucrose-fed flowers but there was no difference in the levels of β-galactosidase activity present in these flowers compared to controls. The observed differences in cell wall pectins due to sucrose feeding were not reflected in differences to the overall firmness of pre-senescent flowers (up to day 3). High levels of galactose persisted into the wilting phase when sucrose-fed flowers were firmer than water-fed controls. We conclude that while sucrose induced significant quantitative and qualitative differences in pectin fractions and galactose content, firmness of floral tissue, particularly during senescence, was not governed by these events alone.