Studies on the metabolism of amino acids during development, ripening and senescence of ‘Pusa Seedless’ grapes

Abstract

Changes in free amino acids were followed during the course of development and senescence of ‘Pusa Seedless’ grape berries. The total free amino acid content continuously increased right from the time of anthesis. The rate of increase was rather slow in the beginning, but accelerated after a lag phase (stage II) of berry development. Glutamic acid was the predominant amino acid in stage I, aspartic acid in stage II and arginine in stage III. In stage III there were massive increases in several amino acids. The ripening process was observed to be intimately associated with the metabolism of arginine, proline and glutamic acid. The proline level in particular increased at the height of the ripening process. During cold storage, the total free amino acid content decreased. Proline content of the berry increased at the expense of arginine and glutamic acid. The study indicated a possible relationship between low arginine/proline ratio and the onset of senescence.