Mobilization of carbohydrates, amino acids and adenine nucleotides in hardwood stems during regrowth after partial shoot harvest in mulberry trees (Morus alba L.)
1986
Yamashita, T.
The course of consumption and storage of protein, carbohyrates, free amino acids and adenine nucleotides in the hardwood stems of mulberry treen (Morus alba L.) was followed during regeneration of the new shoots after top pruning. The top one third of the new shoots developed from low-pruned trees were removed in late July, when the mulberry leaves were used for summer or autumnal rearing of silkworms. Starch and sucrose, which are the major metabolizable carhohydrates in mulberry trees, were directly influenced by top pruning and subsequent regeneration of the new shoots. The sucrose content, which had been depleted for a time after pruning, was restored by the important assimilates from leaves whose photosynthetic activities were still developing, although the starch content decreased. Asparagine, the most abundant amino acids in the stem, increased rapidly after pruning, and then decreased as new shoots developed. A similar pattern of fluctuation occurred in glutamine and glutamic acid contents. It was presumed that these stored amino acids were remobilized and used for protein synthesis in the new shoots. A two-fold rise in the total amount of adenine nucleotide in the stem bark due to an increase in AMP and ATP caused by top pruning, was subsequently restored to the initial value while the new shoots regenerated. Thus, the fluctuations in the adenine nucleotides in the hardwood stems were associated with their mobilization for new growth occurring in the stems.
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