© 1990 Heron Publishing—Victoria, Canada
Variations in amounts of carbohydrates, amino acids and adenine nucleotides in mulberry tree (Morus alba L.) stems during transitional phases of growth
T. Yamashita (1, 2)
1. National Institute of Sericultural and Entomological Science, Tsukuba, Ibaraki, 305, Japan / 2. Tropical Agriculture Research Center, Tsukuba, Ibaraki, 305, Japan / Received August 31, 1988
Summary
Quantitative changes in carbohydrates, amino acids and adenine nucleotides in the stems of mulberry trees (Morus alba L., cv. Shin-ichinose) were followed from spring to early summer and from autumn to early spring. Both ATP and ADP content
of stems increased before bud break, whereas the content of
sucrose, the most abundant sugar among the stem carbohydrates, decreased. The sucrose content fell to its lowest value at
the beginning of May, and then increased rapidly, whereas the starch content decreased suggesting consumption of reserve carbohydrate
and simultaneous accumulation of current photosynthate. This was confirmed by studies in which reserve carbohydrates were
labeled with 14CO2.
Proline content of stems increased from the time of leaf shedding until early spring. Although it was the most abundant amino
acid at the time of bud break, proline rapidly decreased as new shoots developed
and was hardly detectable by the beginning of May. The asparagine and arginine contents increased transiently following bud
break, and then decreased toward summer. Transient increases in glutamine and arginine were noted at the time of leaf shedding.
