Effect of inhibitors on synthesis of fatty acyl chains present in waxes on developing maize leaves

Abstract

Free fatty acids were identified as the fifth lipid class in wax from green leaf segments. They were not isolatable from the wax on yellow leaf segments, which also lacked aldehydes and appeared to have more esters and alkanes than primary alcohols. The chain length spectra of the alkanes and both ester moieties from yellow tissue are distinguishable from those of green tissue by the prominent amounts of shorter homologues, but the homologue distributions of the aldehydes and primary alcohols from the two types of tissue were similar. Tissue slices from yellow leaf segments incorporated 8.7% of the 14C into wax lipids, whereas those from green segments were only half as efficient. In all wax fractions shorter homologues contained relatively more 14C if they came from wax synthesized by yellow rather than green tissue. In wax from green tissue slices, 75 % of the 14C was in 32 carbon chains compared to 29 % in that from yellow tissue slices. Pre-treatment of green tissue slices with 2.5 Tamol of C13AcONa inhibited total wax synthesis by 49 %, primarily via blocking synthesis ofC32 chains. While pre-treatment of yellow tissue slices with 2.5 pmol of triallate inhibited total wax synthesis by only I 0 %, C32 chain synthesis was reduced by 2,600 pmol (41% ). In contrast to the CI3AcONa inhibition, this reduction was to a large extent (I ,700 pmol) compensated for by increases in C28 and C30 chain synthesis.Abbreviations: Avedex = S-(2, 3-dichloroallyl)diisopropylthiocarbamate; CI3AcONa = trichloroacetic acid sodium salt; cpm = counts per minute; DEPH = di-2-ethylhexylphthalate; EPTC = S-ethyldipropylthiocarbamate; G L C = g a s liquid chromatography; M S = m a s s spectrometry; TLC--thin layer chromatography; triallate = S-(2, 3, 3,-trichloroallyl)diisopropylthiocarbamate.

Dominant mutations atCer-yy change barley spike wax into leaf blade wax

“…Presently available evidence suggests that de novo fas synthesis in plant epidermal cells gives rise to the substrates for the wax elongase which is located in the plasmalemma and/or cell walls of the same cells (see 1 1). Differential modification of the biosynthesis of the wax carbon chains by inhibitors, genetic mutation and photoperiodic treatments are best interpreted by the existence of several elongases (see 18,2,19). Before arriving on the cuticle surface, the resulting pools of fatty acyl chains can either serve as substrates for associated pathways such as decarboxylation or reduction, or simply be relased from the elongase(s) as free acids (see 18).…”

Structure of epicuticular waxes on spikes and leaf sheaths of barley as revealed by a direct platinum replica technique

“…When a wax coating is reasonably dense, such as that of barley basal leaf sheaths (Figure 10), barley and most wheat leaf blades (e.g., 22,29) and other surfaces high in primary alcohols (e.g., 3,6,12,14,22,29), it is often difficult to discriminate between individual plates and to characterize their shape. A technique that might be useful in this respect is that of negative staining which has been successfully used in studies of wax tubes (3,15,16). The plates were gently removed by a drop of staining solution when it was touched to the cuticle surface (31).…”

Developmental and topophysical effects on the n-alkanes of Valencia orange fruit epicuticular wax

“…Differences observed in the n-alkane composition with respect to fruit position on the tree suggests a possible effect of light and of temperature on the physiology or biochemistry of wax formation and deposition. This suggestion is presented because the SW quadrant receives higher amounts of direct sunlight and is typically warmer than the NE quadrant, and that light (Macey, 1970;Giese, 1975;Avato et al, 1980) and temperature (Giese, 1975) are reported to influence synthesis of wax components. Such environmental factors have been shown to influence other fruit characteristics.…”