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A Caenorhabditis elegans ORF encoding the presumptive condensing enzyme activity of a fatty acid elongase has been characterized functionally by heterologous expression in yeast. This ORF (F56H11.4) shows low similarity to Saccharomyces cerevisiae genes involved in fatty acid elongation. The substrate specificity of the C. elegans enzyme indicated a preference for ⌬ 6 -desaturated C18 polyunsaturated fatty acids. Coexpression of this activity with fatty acid desaturases required for the synthesis of C20 polyunsaturated fatty acids resulted in the accumulation of arachidonic acid from linoleic acid and eicosapentaenoic acid from ␣-linolenic acid. These results demonstrate the reconstitution of the n-3 and n-6 polyunsaturated fatty acid biosynthetic pathways. The C. elegans ORF is likely to interact with endogenous components of a yeast elongation system, with the heterologous nematode condensing enzyme F56H11.4 causing a redirection of enzymatic activity toward polyunsaturated C18 fatty acid substrates.

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Effects of the Na and Le loci on gibberellin (GA) content and transport in pea (Pisum sativum L.) shoots were studied. GA1, GA8, GA17, GA19, GA20, GA29, GA44, GA8 catabolite, and GA29 catabolite were identified by full-scan gas chromatography-mass spectrometry in extracts of expanding and fully expanded tissues of line C79-338 (Na Le). Quantification of GAs by gas chromatography-singleion monitoring using deuterated internal standards in lines differing at the Na and Le alleles showed that na reduced the contents of GA19, GA20, and GA29 on average to <3% and of GA1 and GA8 to <30% of those in corresponding Na lines. In expanding tissues from Na /e lines, GA1 and GA8 concentrations were reduced to approximately 10 and 2%, respectively, and GA29 content increased 2-to 3-fold compared with those in Na Le plants. There was a close correlation between stem length and the concentrations of GA1 or GA8 in shoot apices in all six genotypes investigated. In na/Na grafts, internode length and GA1 concentration of nana scions were normalized, the GA20 content increased slightly, but GA19 levels were unaffected. Movement of labeled GAs applied to leaves on Na rootstocks indicated that GA19 was transported poorly to apices of na scions compared with GA20 and GA1. Our evidence suggests that GA20 is the major transported GA in peas.Considerable evidence points to GA12 as the native GA controlling internode elongation in a number of plant species, including pea (Pisum sativum L.) (11,15,24,29,30). GA1 is synthesized via the 13-hydroxylation pathway, in which GA12 is 13-hydroxylated to GA53, which is then converted successively to GA44, GA19, and GA20. GA20 is either 23-hydroxylated to GA29 or 3,3-hydroxylated to GA1, which in turn is metabolized to GA8. The 2,B-hydroxylated GAs, GA8 and GA29, are oxidized further at C-2 in pea to give the respective catabolites (11,28). Of these compounds, only GA1 is thought to be active in controlling stem elongation (18). Mutant alleles in several species block GA biosynthesis, resulting in dwarf phenotypes (5,24,29,30). In pea, 12 loci are known to influence plant stature (21) and recessive alleles at four of these reduce GA, biosynthesis (9, 11, 23). The le locus results in reduced conversion of GA20 to GA, (11,12), the na allele is thought to block ent-7a-hydroxykaurenoic acid conversion to GA12-aldehyde, and the Ih and ls alleles apparently affect the conversion of geranylgeranyl Pi to entkaurene (9). Genetic evidence indicates that all of these loci are 'leaky' (20). The quantitative effects of different Le alleles on GA, and GA8 concentrations have been studied previously with differing conclusions (6,10,(25)(26)(27). Whereas similar (6, 27) levels of GA1 were reported in shoots of Progress No. 9 (lele) compared with the nonisogenic Alaska (LeLe), in isogenic plants differing at the Le locus the dwarf genotype produced 10-to 20-fold less GA1 and GA8 than the tall genotype (10,25,26).Recognition of the importance of GA1 in stem elongation and identification of the sites of ...

Ashton Research Station. Bristol BS18 9AF, England). Relations betbveen the content of aroma compounds and the sensory evaluation of 10 raspberry varieties (Rubris idnriis L). Accepted Apr. 2, 1991. Acta Agric. Scand. 41: 447454, 1991 The content of aroma compounds in 10 different raspberry varieties \\as examined and compared with sensory ekaluation ofjam made of these varieties. Raspberry ketone (4-(4-hydroxyphenyl)-butane-2-one) and a-and /%ionone were found to be the most important aroma compounds for all the varieties while linalool and geraniol a.ere found in considerable levels in some varieties. The pure raspberry aroma was found to depend on a relatively high content of the raspberry ketone. If other compounds were present in relatively high amounts the sensory impression w s flo\very or like synthetic raspberry flavour. In some varieties the level of oxidation products as acetoin and hexanoic acid bins high. These compounds have very high odour threshold values but at the sensory evaluation it \$as shown that they may suppress the raspberry flavour.