Changes in sugars in organs of Phalaenopsis florets during different flowering stages of intact plant inflorescences

Abstract

Phalaenopsis flowers possess extraordinary longevity. However, the changes of sugars, including glucose, fructose and sucrose, in organs of floret during different flowering stages of inflorescences attached to a plant have not been reported. To accomplish this, the sugars level in different floret organs were studied at 4 different stages (1. half open, 2. bloom 1 month, 3. bloom 2 months, and 4. wilting). Glucose and fructose were the major soluble sugars in the sepal, petal, labellum, pedicel, and remainder (including the column, anther cap, pollinia, and stigma) of a floret, but their levels decreased from stages 1 to 4. However, the amount of sucrose increased significantly at stage 4 in the sepal, petal, pedicel, and remainder, with the exception that the labellum remained constant throughout all stages. These results demonstrate that glucose and fructose are the major solutes that contribute to floret opening and blooming, and sucrose is salvaged and exported before floret senescence for opening other florets on the same inflorescence. Meanwhile, labellum possesses different sugar metabolism from other organs of Phalaenopsis floret.