Protein and amino acid content in compatible and incompatible peach/plum grafts

Abstract

Amino acid and soluble protein contents were studied in one compatible peach/plum graft (Prunus persica cv. Springtime/Prunus cerasifera cv. myrobalan P 2032) and one incompatible graft (Prunus persica cv. Springtime/Prunus cerasifera cv. myrobalan P 18) for three months after grafting. During a first period, between Days 57 and 78 after grafting, soluble proteins and free amino acids per tree were remobilized from the rootstock in both graft combinations. During a second period, between Days 78 and 89, soluble protein content per tree remained constant in the rootstock of both graft combinations, whereas total free amino acids per tree continued to decrease in the rootstock of the incompatible graft combination and stabilized in the compatible one. In the peach scion and the myrobalan rootstock, asparagine, aspartate, glutamate and arginine were the major free amino acids. Their concentration in the roots was unaffected or only little influenced by incompatibility. Free amino acid and soluble protein concentration in the incompatible rootstock was not indicative of nitrogen starvation or of carbohydrate starvation. In peach scions, at the end of the experiment, the soluble protein concentration was lower in all the organs in the incompatible grafts. The same pattern was found in scion for asparagine, aspartate and glutamate concentrations. This is indicative of nitrogen starvation in the aerial parts.