Effect of Cold Storage on Changes in the Contents of Total and Individual Free Amino Acids in Corollas from Cut ‘Sonia’ Roses

Abstract

Abstract There was an accumulation of total free amino acids (calculated as the sum of the individual amino acids) in corollas from cut ‘Sonia’ roses (Rosa hybrida) stored at 2C (cold-stored flowers) but not in those kept at 20C (control flowers). In cold-stored flowers, senescence was retarded, as indicated by only a slight opening of the corolla and no subsequent petal abscission. Hence, there appeared to be no direct correlation between senescence of cut roses and accumulation of total amino acids in corollas; neither was there a relationship between individual or total free amino acids and protease activity in the corollas from either cold-stored or control flowers. Changes in the contents of all free amino acids, except alanine and lysine, were affected by cold storage. The effect on aspartic acid was statistically significant, but not spectacular. Cold storage delayed the decrease in contents of glutamic acid, asparagine, tyrosine, glycine, leucine, isoleucine and valine, and prevented accumulation of phenylalanine, proline, and histidine. We detected only one theoretically expected interconversion between two amino acids; i.e., glutamic acid to proline, that occurred in corollas from control flowers during the first 6 days of storage. We suggest that the patterns of changes in the contents of tyrosine, valine, isoleucine (or isoleucine plus leucine), and phenylalanine are not restricted to the cultivar Sonia.