Co-Authors:
Gonda, I., Institute of Plant Sciences, Newe ya'Ar Research Center, Agricultural Research Organization, PO Box 1021, Ramat Yishay 30095, Israel, Faculty of Biology, Technion-Israel Institute of Technology, Haifa 32000, Israel
Bar, E., Institute of Plant Sciences, Newe ya'Ar Research Center, Agricultural Research Organization, PO Box 1021, Ramat Yishay 30095, Israel
Portnoy, V., Institute of Plant Sciences, Newe ya'Ar Research Center, Agricultural Research Organization, PO Box 1021, Ramat Yishay 30095, Israel
Lev, S., Institute of Plant Sciences, Newe ya'Ar Research Center, Agricultural Research Organization, PO Box 1021, Ramat Yishay 30095, Israel
Burger, J., Institute of Plant Sciences, Newe ya'Ar Research Center, Agricultural Research Organization, PO Box 1021, Ramat Yishay 30095, Israel
Schaffer, A.A., Institute of Plant Sciences, Newe ya'Ar Research Center, Agricultural Research Organization, PO Box 1021, Ramat Yishay 30095, Israel
Tadmor, Y., Institute of Plant Sciences, Newe ya'Ar Research Center, Agricultural Research Organization, PO Box 1021, Ramat Yishay 30095, Israel
Gepstein, S., Faculty of Biology, Technion-Israel Institute of Technology, Haifa 32000, Israel
Giovannoni, J.J., United States Department of Agriculture, Boyce Thompson Institute for Plant Research, Cornell University, Tower Road, Ithaca, NY 14853, United States
Katzir, N., Institute of Plant Sciences, Newe ya'Ar Research Center, Agricultural Research Organization, PO Box 1021, Ramat Yishay 30095, Israel
Lewinsohn, E., Institute of Plant Sciences, Newe ya'Ar Research Center, Agricultural Research Organization, PO Box 1021, Ramat Yishay 30095, Israel
Abstract:
The unique aroma of melons (Cucumis melo L., Cucurbitaceae) is composed of many volatile compounds biosynthetically derived from fatty acids, carotenoids, amino acids, and terpenes. Although amino acids are known precursors of aroma compounds in the plant kingdom, the initial steps in the catabolism of amino acids into aroma volatiles have received little attention. Incubation of melon fruit cubes with amino acids and α-keto acids led to the enhanced formation of aroma compounds bearing the side chain of the exogenous amino or keto acid supplied. Moreover, L-[ 13C6]phenylalanine was also incorporated into aromatic volatile compounds. Amino acid transaminase activities extracted from the flesh of mature melon fruits converted L-isoleucine, L-leucine, L-valine, L-methionine, or L-phenylalanine into their respective α-keto acids, utilizing α-ketoglutarate as the amine acceptor. Two novel genes were isolated and characterized (CmArAT1 and CmBCAT1) encoding 45.6kDa and 42.7kDa proteins, respectively, that displayed aromatic and branched-chain amino acid transaminase activities, respectively, when expressed in Escherichia coli. The expression of CmBCAT1 and CmArAT1 was low in vegetative tissues, but increased in flesh and rind tissues during fruit ripening. In addition, ripe fruits of climacteric aromatic cultivars generally showed high expression of CmBCAT1 and CmArAT1 in contrast to non-climacteric non-aromatic fruits. The results presented here indicate that in melon fruit tissues, the catabolism of amino acids into aroma volatiles can initiate through a transamination mechanism, rather than decarboxylation or direct aldehyde synthesis, as has been demonstrated in other plants.
תפריט נגישות
ניגודיות עדינה
מונוכרום
הדגשת קישורים
חסימת אנימציה
פונט קריא
סגור
איפוס הגדרות נגישות
להורדת מודול נגישות חינם
