Abstract: In order to explore the effect of benzothiadiazole (BTH) treatment on amino acid accumulation, degradation and metabolism during the growth of grape fruits, ‘Chardonnay’ grape berries at veraison were sprayed with BTH at 50 mg/L and plucked once every 10 d from the next day (60 d after flowering) until maturity (110 d after flowering). The contents of glucose, fructose, sucrose, organic acids and amino acids, as well as enzyme activities related to amino acid degradation and metabolism and the resulting aroma products were analyzed by high performance liquid chromatography (HPLC), an automatic amino acid analyzer and solid phase microextraction combined with gas chromatography-mass spectrometry (SPME-GC-MS). The results showed that glutamic acid, arginine and proline were the major amino acids in ‘Chardonnay’ grape. BTH treatment promoted the accumulation of amino acids, inhibited the production of glucose, fructose and sucrose, increased the contents of tartaric acid and citric acid, and reduced the content of malic acid in mature grapes. Moreover, BTH treatment inhibited the production of free branched aliphatic aroma compounds, and enhanced the activities of aminotransferase (AT), alcohol acyltransferase (AAT), and pyruvate decarboxylase (PDC). Meanwhile, it changed the correlation between total amino acids and alcohol dehydrogenase (ADH) activity, and the correlation between AT and AAT activity and monosaccharides and organic acids content, which in turn affected the production of aroma substances from amino acid metabolism. These results provide theoretical guidance and a practical basis for the application of BTH in controlling grape quality.

Key words: benzothiazole; ‘Chardonnay’ grapes; amino acids; enzyme activities related to degradation and metabolism; aroma