Proposed Biochemical Descriptors for Amino Acids to Evaluate Grape Germplasm.

Abstract

Amino acid profiles in juice were determined by using 259 grape germplasm including 169 cultivars, 81 breeder's lines, 5 rootstocks and 4 clones of wild species. Amino acid contents of cultivars and breeder's lines were higher than those of rootstocks and wild species. For amino acid composition, arginine (Arg), alanine (Ala) and glutamic acid (Glu) were predominant compared with asparatic acid (Asp), threonine (Thr), serine (Ser), valine (Val), methionine (Met), isoleucine (Ile), and leucine (Leu). Based on the primary amino acids, the grape accessions could be classified into the following five types: Glu, Arg, Ala, Arg+Ala and Ala+ Arg. Furthermore, to evaluate amino acid composition easi-ly, a new biochemical descriptor designated as γ ratio= [Thr+Ser+ Ala] /([Asp+Glu] + [Val + Met + Ile + Leu + Arg] ) was introduced. The variation in γ ratio is significantly associated with both use and species parentage, indicating that genetic differentiation for amino acid composition exists among grape germplasm. In addition, as the biochemical descriptor, amino acid profiles in grape germplasm were defined as 3 classes of amino acid content (3 : ?? 1.00 mmol ; 5 : 1.012.00 mmol ; 7 : 2.01 mmol ??, class interval= 1.0 mmol/100 ml equivalent), and 5 classes of γ ratio (1 : ?? 0.50 ; 3 : 0.511.00 ; 5 : 1.011.50 ; 7 : 1.512.00 ; 9 : 2.01 ??, class interval=0.5), respectively.