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

Itay Gonda; Rachel Davidovich-Rikanati; Einat Bar; Shery Lev; Pliaa Jhirad; Yuval Meshulam; Guy Wissotsky; Vitaly Portnoy; Joseph Burger; Arthur A Schaffer; Yaakov Tadmor; James J Giovannoni; Zhangjun Fei; Aaron Fait; Nurit Katzir; Efraim Lewinsohn

doi:10.1016/j.phytochem.2017.12.018

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

Phytochemistry. 2018 Apr:148:122-131. doi: 10.1016/j.phytochem.2017.12.018. Epub 2018 Feb 20.

Authors

Affiliations

¹ Institute of Plant Sciences, Newe Ya'ar Research Center, Agricultural Research Organization, The Volcani Center, P.O. Box 1021, Ramat Yishay, 30095, Israel; The Jacob Blaustein Institutes for Desert Research, Ben-Gurion University of the Negev, Beer-Sheva, 84105, Israel.
² Institute of Plant Sciences, Newe Ya'ar Research Center, Agricultural Research Organization, The Volcani Center, P.O. Box 1021, Ramat Yishay, 30095, Israel.
³ Institute of Plant Sciences, Newe Ya'ar Research Center, Agricultural Research Organization, The Volcani Center, P.O. Box 1021, Ramat Yishay, 30095, Israel; ORT Braude College, Department of Biotechnology Engineering, Karmiel, Israel.
⁴ Institute of Plant Sciences, The Volcani Center, Agricultural Research Organization, P.O. Box 6, Rishon LeZion, 76100, Israel.
⁵ The Jacob Blaustein Institutes for Desert Research, Ben-Gurion University of the Negev, Beer-Sheva, 84105, Israel.
⁶ Boyce Thompson Institute, Cornell University, Ithaca, NY 14853, USA; USDA-ARS Robert W. Holley Center for Agriculture and Health, Ithaca, NY 14853, USA.
⁷ Institute of Plant Sciences, Newe Ya'ar Research Center, Agricultural Research Organization, The Volcani Center, P.O. Box 1021, Ramat Yishay, 30095, Israel. Electronic address: twefraim@agri.gov.il.

PMID: 29448137
DOI: 10.1016/j.phytochem.2017.12.018

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 MgSO₄, 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.

Keywords: (E)-cinnamaldehyde; (E)-cinnamic acid:coenzyme A ligase; Benzoic acid:S-adenosyl-L-methionine carboxyl methyltransferase; Cucumis melo L.; Cucurbitaceae; L-phenylalanine metabolism; Melon; Methyl benzoate; Phenylpropanoid aroma volatiles.

MeSH terms

Cucumis melo / chemistry*
Fruit / chemistry*
Glucosides / chemistry
Glucosides / isolation & purification
Glycosylation
Methionine / metabolism
Nuclear Magnetic Resonance, Biomolecular
Phenylalanine / metabolism*
Phenylalanine Ammonia-Lyase / genetics
Plant Proteins / metabolism
S-Adenosylmethionine / metabolism
Seeds / chemistry
Volatile Organic Compounds / analysis

Substances

Glucosides
Plant Proteins
Volatile Organic Compounds
Phenylalanine
S-Adenosylmethionine
Methionine
Phenylalanine Ammonia-Lyase