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7740547 
Journal Article 
Biosynthesis of alpha-farnesene and its relation to superficial scald development in 'Delicious' apples 
Rupasinghe, HPV; Paliyath, G; Murr, DP 
1998 
Yes 
Journal of the American Society for Horticultural Science
ISSN: 0003-1062 
American Society for Horticultural Science 
123 
5 
882-886 
English 
WOS:000075417600024 
α-Farnesene is an acyclic sesquiterpene hydrocarbon that is a constituent of the volatile components and the surface wax of apples (Malus xdomestica Borkh.). Although oxidation products of α-farnesene have been implicated in the development of superficial scald in apples) the relation between α-farnesene biosynthesis and scald development is not well understood. In vivo labeling studies using isolated tissue segments showed that α-farnesene is derived from trans, trans[1,2-14C or 1-3H]-farnesyl pyrophosphate (FPP) mostly in the skin rather than cortex tissue. Among other labeled products, farnesol was >100-fold higher compared to α-farnesene. However, HPLC analysis of hexane-extractable components from apple skin revealed farnesol is not a predominant natural constituent of apple skin tissue. In addition, trans, trans[1-3H]-farnesol was not converted to α-farnesene by apple skin tissue. Our results indicate that biosynthesis of α-farnesene in apple tissue occurs through the isoprenoid pathway, and the conversion of FPP to α-farnesene is catalyzed by a single sesquiterpene synthase enzyme, trans, trans-α-farnesene synthase, rather than via farnesol as an intermediate. A comparison of α-farnesene biosynthesis between scald-developing and scald-free regions of the same apple showed that incorporation of radiolabel into α-farnesene from trans, trans-[1-3H]-FPP was nearly 3-fold lower in scald-developing skin tissue than in scald-free skin tissue. 
Malus x domestica; storage; sesquiterpene; isoprenoid pathway; farnesol