© 1993 Heron Publishing—Victoria, Canada
Seasonal variations in soluble sugars and starch within woody stems of Cornus sericea L.
E. N. Ashworth (1), V. E. Stirm (1) and J. J. Volenec (2)
1. Department of Horticulture, Purdue University, West Lafayette, IN 47907, USA / 2. Department of Agronomy, Purdue University, West Lafayette, IN 47907, USA / Received May 21, 1993
Summary
Carbohydrate composition changed seasonally in red osier dogwood (Cornus sericea L.) stem tissues. Starch concentration was highest in fall and decreased to a minimum in midwinter. Coincident with the breakdown
of starch in fall, there was an increase in the concentrations of soluble sugars. Soluble sugars were present in highest concentrations
in midwinter. Glucose, fructose, sucrose, and raffinose were the predominant soluble sugars present in both bark and wood
tissues. In early spring, the soluble sugar
concentration decreased and the concentration of starch increased. The seasonal interchange between sugars and starch did
not simply reflect a general quantitative shift in the balance between sugars and starch because qualitative changes in soluble
sugars were also noted. The most striking changes involved the trisaccharide raffinose. Raffinose was barely detectable in
summer and early fall, but increased to one fifth and one third of the total soluble sugars in January samples of bark and
wood tissues, respectively. The potential physiological role of raffinose in overwintering red osier dogwood tissue is discussed.
Keywords:
bark, carbohydrate composition, cold acclimation, fructose, glucose, raffinose, red osier dogwood, sucrose.
