Cinnamate‐CoA ligase is involved in biosynthesis of benzoate‐derived biphenyl phytoalexin in Malus × domestica ‘Golden Delicious’ cell cultures

Abstract

Apple (Malus sp.) and other genera belonging to the sub-tribe Malinae of the Rosaceae family produce unique benzoic acid-derived biphenyl phytoalexins. Cell cultures of Malus domestica cv. 'Golden Delicious' accumulate two biphenyl phytoalexins, aucuparin and noraucuparin, in response to the addition of a Venturia inaequalis elicitor (VIE). In this study, we isolated and expressed a cinnamate-CoA ligase (CNL)-encoding sequence from VIE-treated cell cultures of cv. 'Golden Delicious' (M. domestica CNL; MdCNL). MdCNL catalyses the conversion of cinnamic acid into cinnamoyl-CoA, which is subsequently converted to biphenyls. MdCNL failed to accept benzoic acid as a substrate. When scab-resistant (cv. 'Shireen') and moderately scab-susceptible (cv. 'Golden Delicious') apple cultivars were challenged with the V. inaequalis scab fungus, an increase in MdCNL transcript levels was observed in internodal regions. The increase in MdCNL transcript levels could conceivably correlate with the pattern of accumulation of biphenyls. The C-terminal signal in the MdCNL protein directed its N-terminal reporter fusion to peroxisomes in Nicotiana benthamiana leaves. Thus, this report records the cloning and characterisation of a cinnamoyl-CoA-forming enzyme from apple via a series of in vivo and in vitro studies. Defining the key step of phytoalexin formation in apple provides a biotechnological tool for engineering elite cultivars with improved resistance.

Biopesticide Trunk Injection Into Apple Trees: A Proof of Concept for the Systemic Movement of Mint and Cinnamon Essential Oils

“…Phytoalexins include diverse plant secondary metabolites biosynthesised in response to pathogens and certain abiotic stresses. In the subtribe Malinae of the Rosaceae family, the phytoalexins biphenyl and dibenzofuranare are produced upon pathogen attack (Chizzali and Beerhues, 2012) and after elicitor-treated cell cultures (Saini et al, 2019;Teotia et al, 2019). The production of phytoalexins following treatment with EOs could also be an interesting prospect in order to determine and clarify the defence induction potential of these compounds as well as their potential impact on pathogens.…”

A promiscuous coenzyme A ligase provides benzoyl‐coenzyme A for xanthone biosynthesis in Hypericum

“…The Plant Journal, (2020), 104, 1472-1490 phenylpropanoid pathway (Vogt, 2010;Gaid et al, 2011) nor a CNL responsible for the initial step of the CoA-dependent routes (Gaid et al, 2012;Klempien et al, 2012;Lee et al, 2012;Teotia et al, 2019). Apart from benzoic acid, propanoic, butyric, isobutyric and hexanoic acids are the preferred substrates for HcAAE1, indicating the promiscuous nature of this enzyme.…”

“…The affinities of Tm AAE4 and Hc AAE1 to benzoic acid are comparable ( K m = 172 and 100 µ m , respectively). The effect of potassium on the activity of Tm AAEs remains open, although the detected BZL activity in the cell‐free extracts and the recombinant CNLs are significantly stimulated (Gaid et al ., 2012; Klempien et al ., 2012; Teotia et al ., 2019; Saini et al ., 2020). To our knowledge, no cDNA encoding BZL has previously been isolated from the angiosperms, endorsing Hc AAE1 as the feasible candidate.…”

“…Hc AAE1 does not accept substituted benzoic and cinnamic acids, as determined by the sensitive luciferase, HPLC‐diode array detection, LC‐MS and spectrophotometric assays, which is an additional peerless signature for Hc AAE1. The inability to activate 4‐coumaric and trans ‐cinnamic acids indicates that Hc AAE1 is neither a 4CL involved in the general phenylpropanoid pathway (Vogt, 2010; Gaid et al ., 2011) nor a CNL responsible for the initial step of the CoA‐dependent routes (Gaid et al ., 2012; Klempien et al ., 2012; Lee et al , 2012; Teotia et al ., 2019). Apart from benzoic acid, propanoic, butyric, isobutyric and hexanoic acids are the preferred substrates for Hc AAE1, indicating the promiscuous nature of this enzyme.…”

“…Despite the simple structure, benzoic acid and hence benzoyl‐CoA are formed by various concurrent pathways, which complicates the full understanding of the biosynthesis (Wildermuth, 2006; Widhalm and Dudareva, 2015). Nevertheless, a substantial amount of research has increased the knowledge of benzoyl‐CoA biosynthesis in plants over the last two decades (Abd El‐Mawla and Beerhues, 2002; Gaid et al ., 2012; Saini et al ., 2017; Park et al ., 2017; Saini et al ., 2019; Teotia et al ., 2019; Saini et al ., 2020). This is particularly true for Petunia hybrida (Boatright et al ., 2004; Orlova et al ., 2006; Van Moerkercke et al ., 2009; Colquhoun et al ., 2012; Klempien et al ., 2012; Qualley et al ., 2012; Adebesin et al ., 2018).…”