Gene mutation in barley inhibiting the production and use of C 26 chains in epicuticular wax formation

1980

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A direct platinum replica technique is described for studying cuticle surfaces with few or no projecting wax structures. It is furthermore demonstrated that the structure of some small plate waxes can be elucidated using negative staining.Three types of epicuticular waxes are present on barley cuticular surfaces: (i) long, thin tubes and 13-diketone lipids characterize that on the glumes, lemmas and uppermost leaf sheaths; (ii) highly lobed plates, large amounts of primary alcohols (predominantly C26) and an absence of ~-diketone lipids characterize that on the leaf blades and lower leaf sheaths; and (iii) thin plates, frequently horizontal to the surface, major amounts of hydrocarbons and esters and an absence of ~,-diketone lipids characterize that on the awns. When mutations cause the absence or a major reduction of the dominating lipids in one of the first two types of waxes, the wax deposits resemble the third type.The mutation cer-s 31 restricts the presence of wax tubes to patches on the lemmas, paleas and glumes giving them a grainy appearance. While the effect is greatest on the lemmas of the median floret rows, the reduction of the l~-diketone lipids is similar on both median and lateral spikelets. In the double mutant hex-v 3 cer-s 3~ the lateral florets become fertile, but the differential effect of cer-s 31 on the median and lateral rows is retained.Abbreviations: C/Au/Pd replica = gold-palladium pre-shadowed carbon replica; GLC = gas liquid chromatography; Pt/C replica = direct platinum shadowed replica; TLC = thin layer chromatography.

Section: Leaf Sheath Waxessupporting

confidence: 77%

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

Simpson

1980

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“…In fact the wax classes identified, their relative amounts and chain length compositions were all within the range of variation known from other Gramineae leaves such as barley (16,35), corn (5), oats (31), wheat (32) and various grasses (29,30,33). The only exception to this generalization was the identification of three nonan-2-ol esters.…”

Section: Discussionsupporting

confidence: 51%

Nonan-2-ol esters in sorghum leaf epicuticular wax and their collection by preparative gas chromatography

Mikkelsen

Madsen

1984

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Epicuticular wax from sorghum seedling leaves was isolated and analyzed by TLC and GC. Its composition was remarkably similar to that of waxes on many other Gramineae leaves with the exception that three alkan-2-ol esters (nonan-2-ol docosanoate, nonan-2-ol tetracosanoate, and nonan-2-ol hexacosanoate) were present. This was unexpected as such esters have hitherto only been reported in waxes of plants with the capability of synthesizing 13-diketone lipids. The C~,-C~s alkan-2-ol esters were separated from the C~s-C~ alkan-1-ol esters by preparative GC.The column effluent was passed through a small Dexsil-300 trap maintained at 150 ~ and the esters eluted therefrom with chloroform. This technique gave better than 90% recovery of a [1-"C]-C~. ester. INTRODUCI'IONDisclosing the I~-diketone (primarily, hentriacontan-14,16-dione and 25-hydroxyhentriacontan-14,16-dione) and esterified alkan-2-ol (primarily tridecan-2-ol and pentadecan-2-ol) biosynthetic pathways and their genetic control is our primary goal. As biological material we have used barley spikes of the eceriferum mutants which determine synthesis and deposition of the very long chain lipids on the external surface of epidermal cell walls. Since large amounts of material would spur attempts to isolate the enzymes involved, we have been looking for a plant which synthesizes one or more of the specified lipids on rapidly growing seedling leaves. Herein we identify nonan-2-ol Abbreviations: GC = gas chromatography; MS = mass spectrometry; TLC = thin layer chromatography: TMS = trimethylsilyl.Springer-Verlag

“…That greater amounts of the longer chain free alcohols are present on the awns compared to the spike minus awns (Table IV) is the reverse of what was observed for the free acids (Table III). The dominance of the C2~ chain length is also characteristic for the leaf free primary alcohols (8,36,38) where it may account for as much as 90% of this wax class. When the importance of the C2~ chain length is reduced in leaf waxes, however, either via a gene mutation or the environmental growth conditions, the shorter C22 and C24 homologues become prominent (8,9,36,38) and not the longer C2s, C30 and C32 chain lengths as in the spike waxes.…”

Section: Chain Length Distributions Of the Lipid Classes On Cer-u 69 mentioning

confidence: 99%

“…From the remainder of the wax sample the hydrocarbons, esters, aldehydes, primary alcohols and secondary alcohols were isolated via preparative TLC (36). To determine the chain length compositions of the hydrocarbons, esters, 13-diketones, primary alcohols and free fatty acids, they and/or their appropriate derivatives were subjected to gas liquid chromatography (GLC) (36,37,38,42). The parameters used in the GLC procedure and the sources of internal standards have been detailed in the above references.…”

Section: Foma and The Mutants Cer-d 5 -A 6 -If -M 15 -S ~' mentioning

confidence: 99%

“…The lipid class composition of a wax sample was determined from thin layer chromatograms (TLC) of the wax and standards run in two different solvent systems (42). Wax classes were isolated as follows: With the aid of column chromatography, the free fatty acids and when present the 13-diketones and hydroxy-fl-diketones were removed from a wax sample by complex formation and then recovered as described previously (27,38). From the remainder of the wax sample the hydrocarbons, esters, aldehydes, primary alcohols and secondary alcohols were isolated via preparative TLC (36).…”

Section: Foma and The Mutants Cer-d 5 -A 6 -If -M 15 -S ~' mentioning

confidence: 99%

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Composition of epicuticular waxes on barley spikes

Netting

1976

Hydrocarbons, alkan-l-ol and alkan-2-ol containing esters, 13-diketones, aldehydes, primary alcohols, hydroxy-13-diketones, free fatty acids and sometimes secondary alcohols are major lipid classes of epicuticular waxes on the spikes of the three wild type barley varieties Bonus, Foma and Carlsberg-ll and many of the 40 eceriferum (cer) mutants examined. Division of the spikes into two parts, the awns and the spike minus awns, before wax isolation reveals that (i) 13-diketones, hydroxy-13-diketones and esterified alkan-2-ols occur only on the spike minus awns, (ii) secondary alcohols are present only on the awns of Foma and its mutants and (iii) the other lipid classes are found on both parts of the spike. The chain length distributions of the lipid classes common to both parts of the spike are in some cases similar and in others different.