ISHS Acta Horticulturae 564: IV International Symposium on Mineral Nutrition of Deciduous Fruit Crops
EVOLUTION OF NITROGEN AND AMINO ACIDS IN PEACH AND PLUM BARK |
| Keywords: | reserves, bark storage proteins, Southern hemisphere, Chile. |
| Abstract:
Samples of one-year-old tissue of peach (Prunus persica L.) cv. O’Henry and plum (Prunus salicina L.) cv. Angeleno were collected monthly from a commercial orchard in Santiago, Chile (33º38’S). Samples were immediately frozen in liquid nitrogen to be analyzed. Nitrogen concentration (Nc), total amino acids (TA), free amino acids (FA), proteic amino acids (PA) and protein profiles were analyzed in each sample. For total N, samples were ground, oven dried and analyzed using the Kjeldahl method. For TA, samples were ground in liquid N and hydrolyzed using 6N HCL. For FA, samples were extracted with ethanol at 60ºC. Proteic amino acids were obtained as the difference between TA and FA. Proteins were extracted and separated using SDS-PAGE analysis. Nitrogen concentration, TA, PA and soluble proteins showed a seasonal variation, with maximum values during mid-winter and minimum in November or December. In peach bark, total N ranged from 1.56% in July to 0.63% in December, and in plum from 1% in July to 0.71% in December. Total amino acids in peach ranged from 230 mg/g FW in June and 90 mg/g FW in November (spring), and in plum from 150 mg/g FW in April to 60 mg/g FW in November. Free amino acids in peach ranged between 20 mg/g FW in Feb and 4.5 mg/g FW in November, and in plum between 15 mg/g FW in April and 4.5 mg/g FW in August. A 60-kDa protein was detected in both species during fall and winter. This protein behaves as a bark storage protein and may play an important role as a N reserve in these two species. | |
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