Spring Mobilization of Protein Nitrogen in Apple Bark

Abstract

Mobilization of protein nitrogen in the spring was studied in bark of stems of unringed and double stem-ringed apple rootstocks M.7 given different nitrogen treatments.A ready protein hydrolysis occurred; the proteins contributed the greater part of the storage nitrogen exported to tlie growing parts. Protein hydrolysis was little affected by the suppjy of newly absorbed nitrogen. Movement of nitrogen out of the bark between the rings could not be demonstrated. Protein breakdown in the isolated bark sections was slightly reduced.Arginine was the predominant amino acid in the proteins of the trees with a high level of storage nitrogen but was not conspicuous in the low-nitrogen trees. The protein composition changed little during hydrolysis. Only the share of arginine in the Hgh-nitrogen trees dropped appreciably. It is suggested that the high-nitrogen trees possess a special storage protein characterized by a high arginine content.Analysis of the nitrogen fraction of isolated bark sections stowed that the composition of the soluble nitrogen was characterized by a high level of asparagine and especially of arginine» and was qtiite different from the composition of the proteins. The data suggest that the asparagine in particular originated largely from transformation of the various amino acids set free during protein hydrolysis.

Effect of nitrogen supply on growth and internal nitrogen cycling within deciduous trees

“…Isotopic N has been used in several studies to trace the movement of previously assimilated N to the current year's growth (e.g., Weimbaum and Muraoka, 1986 Millard and Neilsen (1988 Millard and Neilsen (1988 (Tromp and Ovaa, 1973). …”

Isolation and Spring Mobilization of Proteins in Citrus Trees (Citrus unshiu Marc.)

“…Storage proteins in fruit trees have received little attention until quite recently, although in apple trees there is a fund of information emerging. Although the presence of an arginine-rich protein has been reported in apple shoot bark (8,10), storage proteins have only been partially characterized.…”

The Occurrence and Nature of Ornithine Carbamoyltransferase in Senescing Apple Leaf Tissue

“…During the time that leaves are exporting amino acids, arginine increases greatly in the xylem sap and in the shoot's woody tissues (15,16). In the spring, argininenitrogen accounts for more than 70% of the soluble nitrogen in the wood of an apple tree (7) and constitutes a large percentage of protein-nitrogen as well as soluble nitrogen in the bark tissues (17). The spring increase in soluble, free arginine in bark tissue is greater than can be attributed to the release of arginine from protein, suggesting that arginine is synthesized in bark tissue in the spring (17).…”

“…In the spring, argininenitrogen accounts for more than 70% of the soluble nitrogen in the wood of an apple tree (7) and constitutes a large percentage of protein-nitrogen as well as soluble nitrogen in the bark tissues (17). The spring increase in soluble, free arginine in bark tissue is greater than can be attributed to the release of arginine from protein, suggesting that arginine is synthesized in bark tissue in the spring (17). Recent work has shown that apple-stem tissue has the ability to interconvert ornithinecitrulline-arginine at any time in the year but with a greater rate in the spring (5).…”

“…The amino acid arginine is an important storage form of nitrogen (4, [15][16][17]. During the time that leaves are exporting amino acids, arginine increases greatly in the xylem sap and in the shoot's woody tissues (15,16).…”