Effects of Dwarfing Rootstocks and Interstems on the Free Amino Acid and Protein Levels in Apple Roots1

Abstract

Abstract The levels of total free amino acids, arginine, aspartic acid, glutamic acid, serine and protein were determined in the roots of apple plants grafted with (a) rootstocks of MM 111, MM 106 or EM IX or (b) rootstock MM 111 plus interstems 1, 3, 5, or 7 inches long of ‘Red Delicious’ (RD), MM 106 or EM IX; all scions were RD. The levels of free amino acids and protein in the rootstocks were not related to their dwarfing effect. The level of free amino acids was very low in MM 106. The levels of free amino acids in the roots of plants with MM 106 interstem increased as the interstem was increased in length. Plants with EM IX interstem had high and nearly equal levels of free amino acids in the roots when the interstem was 3, 5, or 7 inches long, but there was a much lower level in the roots of plants with a 1-inch interstem. The levels of protein in the roots of plants with MM 106 or EM IX interstem showed smaller differences but followed the same pattern as that of free amino acids. Among control plants free amino acids and protein were lower in roots of plants with 2 grafts than in those with 1 graft, and free amino acids were lower in the roots of those with 5- and 7-inch interstems than in those with 1- and 3-inch interstems. The levels of individual amino acids were variable, but the levels of aspartic acid and serine followed a pattern similar to that of total free amino acids.