Studies on the qualitative changes in the amino acid, sugar and organic acid contents of tomato fruit during pathogenesis by alternaria solani

Qualitative changes in the amino acid, sugar and organic acid contents of the tomato fruit during pathogenesis causaed by Alternaria solani were investigated chromatographically. Marked differences in the amino acid, sugar and organic acid contents of the healthy and diseased tomato fruits were noted. Total in all only eight different amino acids, viz., Lysine, Arginine, Histidine, Aspartic acid, Glutamic acid, Alanine, Methionine and one Unidentified amino acid (Rf. 0.36) were detected in the extracts of healthy tomato fruits while thirteen amino acids namely as Cysteine, Lysine, Arginine, Histidine, Aspartic acid, Glutamic acid, Alanine, Tyrosin, Methionine, Valine, Leucine, Asparagine and one Unidentified amino acid having Rf value 0.38, were successfully detected in the extracts of diseased tomato fruits. These results indicated that five new amino acids, i.e., Cystine, Tyrosine, Valine, Leucine and Asparagine were synthesized in the diseased tissues after infection of Alternaria solani. The concentration of two amino acids namely Glutamic acid and Methionine have been found to be increased in diseased tissues in comparison to healthy tissues, as observed visually by seeing the intensity of colour of spots on the developed chromatograms. The chromatographic analysis of extract of healthy tissues showed the presence of four different sugars, i.e., Sucrose, Glucose, Maltose and Fructose in healthy tomato fruits. When extract of diseased tissues of inoculated (infected) tomato fruits were analyzed then it was found that only two sugars namely Fructose and Sucrose have been detected and remaining two susgars, i.e., Maltose and Glucose have not been detected even upto 12 days incubation periods. These results indicated that these two sugars may utilized during pathogenesis by Alternaria solani. The different length of given incubation period (4 days to 12 days) have no pronounced effect on the sugar levels, i.e., their concentration and composition. In the healthy tomato fruits (uninoculated) only five organic acids namely Fumaric acid, Malonic acid, Malic acid, Citric acid and Tartaric acid have been detected, in all the given incubation periods. When the inoculated diseased tomato fruits of 4, 8 and 12 days incubation, were analyzed for organic acids detection then it was found that total six organic acids present. Besides, five organic acids which were initially present in healthy tissues, only one new organic acid, i.e., Succinic acid was produced in diseased tissues. These results indicates that Succinic acid was synthesized after infection during the disease development. There was no remarkable changes in the concentration and compositin of detected organic acids in diseased and healthy tissues during various incubation periods.