Differential metabolism of L-phenylalanine in the formation of aromatic volatiles in melon (Cucumis melo L.) fruit Academic Article uri icon

abstract

  • Studies on the active pathways and the genes involved in the biosynthesis of L-phenylalanine-derived volatiles in fleshy fruits are sparse. Melon fruit rinds converted stable-isotope labeled L-phe into more than 20 volatiles. Phenylpropanes, phenylpropenes and benzenoids are apparently produced via the well-known phenylpropanoid pathway involving phenylalanine ammonia lyase (PAL) and being ( E )-cinnamic acid a key intermediate. Phenethyl derivatives seemed to be derived from L-phe via a separate biosynthetic route not involving ( E )-cinnamic acid and PAL. To explore for a biosynthetic route to ( E )-cinnamaldehyde in melon rinds, soluble protein cell-free extracts were assayed with ( E )-cinnamic acid, CoA, ATP, NADPH and MgSO 4 , producing ( E )-cinnamaldehyde in vitro . In this context, we characterized CmCNL, a gene encoding for ( E )-cinnamic acid:coenzyme A ligase, inferred to be involved in the biosynthesis of ( E )-cinnamaldehyde. Additionally we describe CmBAMT , a SABATH gene family member encoding a benzoic acid: S -adenosyl-L-methionine carboxyl methyltransferase having a role in the accumulation of methyl benzoate. Our approach leads to a more comprehensive understanding of L-phe metabolism into aromatic volatiles in melon fruit.

publication date

  • January 1, 2018