Determination of Hesperidin and Limonin Levels as Part of the Defense Mechanism of Some Lemon Varieties [Citrus limon （L,） Burm f.] against Mal Secco Disease [Phoma tracheiphila （Petri） Kanc,et Ghik,]

In this paper, it was aimed to identified and quantified hesperidin and limonin compounds using HPLC （High Performance Liquid Chromatography） techniques against to developing of mal secco disease caused by Phoma tracheiphila. Six citrus lemon varieties （Meyer, Kiitdiken, Enterdonato, Yediveren, Sweet lemon and Euroka） were infected by P. tracheiphila and artificial inoculation were applied in vivo conditions. Before and after inoculation, leaf, branch and stem samples were taken from each lemon varieties. The results show that the amount of hesperidin and limonin concentration was increased after the inoculations at various levels based on the lemon cultivars. Various concentrations （1, 5, 10, 25, 50, 75, 100 ppm） of hesperidin and limonin compounds were also tested under in vitro conditions to compare response of P. tracheiphila development. According to the results, hesperidin and limonin compounds play an important role against to P. tracheiphila development and Sweet Lemon variety was found to be the most resistance both observation and HPLC results.

Quantification and Comparison of Sugars, Carboxylic Acids and Vitamin C Components of Various Citrus Species by HPLC Techniques

Six orange varieties （Washington Navel, Navelina, Navelate, Lane Late, Cara Cara, Valencia）, four mandarin varieties （Okitsu Wase, Dobashi Beni, Ortanique, Satsuma Owari） and two grapefruit varieties （Star Ruby and Rio Red） were evaluated for their fruit quality characteristics such as fructose, glucose, sucrose, total sugars, malic acid, citric acid and Vitamin C contents. Sugars, carboxylic acids, and vitamin C contents of citrus juices were identified and quantified by HPLC （High Performance Liquid Chromatography） technique. The predominating individual sugars were detected as sucrose in all mandarin and orange varieties except grapefruit varieties. Whereas fructose and glucose were found to be higher in grapefruit varieties, citric acid was considered as a major carboxylic acid in all citrus species and detected in oranges higher concentration than mandarin and grapefruit varieties. Furthermore, vitamin C content of grapefruit juices were detected higher concentration than the oranges （except cv. Valencia） and mandarins. Our results showed that itrus species differed in not only species but also varieties based on the sugar and acid characteristics.