Identification of In-Chain-Functionalized Compounds and Methyl-Branched Alkanes in Cuticular Waxes of Triticum aestivum cv. Bethlehem

Abstract

In this work, cuticular waxes from flag leaf blades and peduncles of Triticum aestivum cv. Bethlehem were investigated in search for novel wax compounds. Seven wax compound classes were detected that had previously not been reported, and their structures were elucidated using gas chromatography-mass spectrometry of various derivatives. Six of the classes were identified as series of homologs differing by two methylene units, while the seventh was a homologous series with homologs with single methylene unit differences. In the waxes of flag leaf blades, secondary alcohols (predominantly C27 and C33), primary/secondary diols (predominantly C28) and esters of primary/secondary diols (predominantly C50, combining C28 diol with C22 acid) were found, all sharing similar secondary hydroxyl group positions at and around C-12 or ω-12. 7- and 8-hydroxy-2-alkanol esters (predominantly C35), 7- and 8-oxo-2-alkanol esters (predominantly C35), and 4-alkylbutan-4-olides (predominantly C28) were found both in flag leaf and peduncle wax mixtures. Finally, a series of even- and odd-numbered alkane homologs was identified in both leaf and peduncle waxes, with an internal methyl branch preferentially on C-11 and C-13 of homologs with even total carbon number and on C-12 of odd-numbered homologs. Biosynthetic pathways are suggested for all compounds, based on common structural features and matching chain length profiles with other wheat wax compound classes.

A quest for the biological sources of long chain alkyl diols in the western tropical North Atlantic Ocean

“…(Sinninghe Damsté et al, 2003;Rampen et al, 2009), and to a lesser extent from A. radians (Rampen et al, 2011), whereas the 1,13-and 1,15-diols are thought to be associated with Eustigmatophyceae (Rampen et al, 2014a, and references cited therein). Previous studies highlighted indeed good correlations in the fluxes of C 28 and C 30 1,14-diols in the water column of the Arabian Sea (Rampen et al, 2007) and the northwestern Indian Ocean (Rampen et al, 2008). Proboscia spp.…”

“…In general, it is thought that 1,13-and 1,15-diols derive from a different source than 1,14-diols in the marine realm (Sinninghe Damsté et al, 2003;Rampen et al, 2007Rampen et al, , 2011. Indeed, linear regressions showed that the concentration of the C 30 1,15-diol is significantly correlated with those of the C 30 1,13-and C 32 1,15-diols ( Fig.…”

TaCER1‐1A is involved in cuticular wax alkane biosynthesis in hexaploid wheat and responds to plant abiotic stresses

“…For example, many cereal crop species have high concentrations of β‐diketones in their waxes (von Wettstein‐Knowles, ). In this context, wheat waxes have been investigated in much chemical detail, revealing substantial variation between different cultivars, organs, and growth stages (Racovita et al, ; Racovita & Jetter, ; Racovita & Jetter, ). Further research suggested that wax alkanes accumulated mostly in the heading and later stages of wheat development, in particular on flag leaf blades, peduncles, and spikes (Wang et al, ; Wang et al, ).…”

Epicuticular Waxes Provide Insights into Phytochemical Differentiation of Natural Populations ofPinus mugoTurrasensu stricto

“…[14] Cuticular waxes are complex mixtures of very-long-chain (VLC, > C 20 ) saturated aliphatic compounds, bearing no functionality or only one functional group at one end of the carbon chain (hence a primary functionality). [15] Most commonly encountered are homologous series of even-numbered fatty acids, primary alcohols, alkyl esters and aldehydes, as well as odd-numbered alkanes, secondary alcohols and ketones. [13,16] In the wax mixtures of some plant species, alicyclic compounds (e. g., diterpene acids, hydroxy diterpenes, triterpenoids) and aromatic compounds (e. g., alkylresorcinols) may also be quite abundant.…”