RESUMO
Terpenes are important compounds in plant trophic interactions. A meta-analysis of GC-MS data from a diverse range of apple (Malus × domestica) genotypes revealed that apple fruit produces a range of terpene volatiles, with the predominant terpene being the acyclic branched sesquiterpene (E,E)-α-farnesene. Four quantitative trait loci (QTLs) for α-farnesene production in ripe fruit were identified in a segregating 'Royal Gala' (RG) × 'Granny Smith' (GS) population with one major QTL on linkage group 10 co-locating with the MdAFS1 (α-farnesene synthase-1) gene. Three of the four QTLs were derived from the GS parent, which was consistent with GC-MS analysis of headspace and solvent-extracted terpenes showing that cold-treated GS apples produced higher levels of (E,E)-α-farnesene than RG. Transgenic RG fruit downregulated for MdAFS1 expression produced significantly lower levels of (E,E)-α-farnesene. To evaluate the role of (E,E)-α-farnesene in fungal pathogenesis, MdAFS1 RNA interference transgenic fruit and RG controls were inoculated with three important apple post-harvest pathogens [Colletotrichum acutatum, Penicillium expansum and Neofabraea alba (synonym Phlyctema vagabunda)]. From results obtained over four seasons, we demonstrate that reduced (E,E)-α-farnesene is associated with decreased disease initiation rates of all three pathogens. In each case, the infection rate was significantly reduced 7 days post-inoculation, although the size of successful lesions was comparable with infections on control fruit. These results indicate that (E,E)-α-farnesene production is likely to be an important factor involved in fungal pathogenesis in apple fruit.
Assuntos
Frutas/genética , Frutas/metabolismo , Regulação da Expressão Gênica de Plantas , Malus/genética , Malus/metabolismo , Doenças das Plantas/imunologia , Sesquiterpenos/metabolismo , Colletotrichum/patogenicidade , Resistência à Doença , Regulação para Baixo , Fungos/patogenicidade , Cromatografia Gasosa-Espectrometria de Massas , Ligação Genética , Genótipo , Penicillium/patogenicidade , Doenças das Plantas/microbiologia , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Plantas Geneticamente Modificadas/genética , Locos de Características Quantitativas , Interferência de RNA/imunologia , Terpenos/metabolismoRESUMO
Phenylpropenes, such as eugenol and trans-anethole, are important aromatic compounds that determine flavour and aroma in many herbs and spices. Some apple varieties produce fruit with a highly desirable spicy/aromatic flavour that has been attributed to the production of estragole, a methylated phenylpropene. To elucidate the molecular basis for estragole production and its contribution to ripe apple flavour and aroma we characterised a segregating population from a Royal Gala (RG, estragole producer) × Granny Smith (GS, non-producer) apple cross. Two quantitative trait loci (QTLs; accounting for 9.2 and 24.8% of the variation) on linkage group (LG) 1 and LG2 were identified that co-located with seven candidate genes for phenylpropene O-methyltransferases (MdoOMT1-7). Of these genes, only expression of MdoOMT1 on LG1 increased strongly with ethylene and could be correlated with increasing estragole production in ripening RG fruit. Transient over-expression in tobacco showed that MdoOMT1 utilised a range of phenylpropene substrates and catalysed the conversion of chavicol to estragole. Royal Gala carried two alleles (MdoOMT1a, MdoOMT1b) whilst GS appeared to be homozygous for MdoOMT1b. MdoOMT1a showed a higher affinity and catalytic efficiency towards chavicol than MdoOMT1b, which could account for the phenotypic variation at the LG1 QTL. Multiple transgenic RG lines with reduced MdoOMT1 expression produced lower levels of methylated phenylpropenes, including estragole and methyleugenol. Differences in fruit aroma could be perceived in these fruit, compared with controls, by sensory analysis. Together these results indicate that MdoOMT1 is required for the production of methylated phenylpropenes in apple and that phenylpropenes including estragole may contribute to ripe apple fruit aroma.
Assuntos
Anisóis/metabolismo , Frutas/metabolismo , Malus/metabolismo , Metiltransferases/metabolismo , Proteínas de Plantas/genética , Derivados de Alilbenzenos , Etilenos/metabolismo , Eugenol/análogos & derivados , Eugenol/metabolismo , Frutas/genética , Regulação da Expressão Gênica de Plantas , Isoenzimas/genética , Isoenzimas/metabolismo , Malus/genética , Metiltransferases/genética , Dados de Sequência Molecular , Odorantes , Filogenia , Proteínas de Plantas/metabolismo , Plantas Geneticamente Modificadas , Locos de Características QuantitativasRESUMO
The 'fruity' attributes of ripe apples (Malus × domestica) arise from our perception of a combination of volatile ester compounds. Phenotypic variability in ester production was investigated using a segregating population from a 'Royal Gala' (RG; high ester production) × 'Granny Smith' (GS; low ester production) cross, as well as in transgenic RG plants in which expression of the alcohol acyl transferase 1 (AAT1) gene was reduced. In the RG × GS population, 46 quantitative trait loci (QTLs) for the production of esters and alcohols were identified on 15 linkage groups (LGs). The major QTL for 35 individual compounds was positioned on LG2 and co-located with AAT1. Multiple AAT1 gene variants were identified in RG and GS, but only two (AAT1-RGa and AAT1-GSa) were functional. AAT1-RGa and AAT1-GSa were both highly expressed in the cortex and skin of ripe fruit, but AAT1 protein was observed mainly in the skin. Transgenic RG specifically reduced in AAT1 expression showed reduced levels of most key esters in ripe fruit. Differences in the ripe fruit aroma could be perceived by sensory analysis. The transgenic lines also showed altered ratios of biosynthetic precursor alcohols and aldehydes, and expression of a number of ester biosynthetic genes increased, presumably in response to the increased substrate pool. These results indicate that the AAT1 locus is critical for the biosynthesis of esters contributing to a 'ripe apple' flavour.
Assuntos
Acetiltransferases/genética , Ésteres/metabolismo , Malus/genética , Proteínas de Plantas/genética , Locos de Características Quantitativas , Acetiltransferases/metabolismo , Acetiltransferases/fisiologia , Mapeamento Cromossômico , Regulação para Baixo , Estudos de Associação Genética , Ligação Genética , Variação Genética , Malus/metabolismo , Dados de Sequência Molecular , Proteínas de Plantas/metabolismo , Proteínas de Plantas/fisiologia , Plantas Geneticamente Modificadas/metabolismoRESUMO
Musth in male elephants is an annual period of heightened sexual activity and aggression that is linked to physical, sexual and social maturation. It is mediated by the release of chemical signals such as the pheromone frontalin, which exists in two chiral forms (molecular mirror images, or enantiomers). Here we show that enantiomers of frontalin are released by Asian elephants in a specific ratio that depends on the animal's age and stage of musth, and that different responses are elicited in male and female conspecifics when the ratio alters. This precise control of communication by molecular chirality offers insight into societal interactions in elephants, and may be useful in implementing new conservation protocols.
Assuntos
Compostos Bicíclicos Heterocíclicos com Pontes/química , Compostos Bicíclicos Heterocíclicos com Pontes/farmacologia , Elefantes/fisiologia , Feromônios/química , Feromônios/metabolismo , Comportamento Sexual Animal/efeitos dos fármacos , Envelhecimento/fisiologia , Animais , Compostos Bicíclicos Heterocíclicos com Pontes/metabolismo , Feminino , Masculino , Feromônios/farmacologia , Gravidez , Comportamento Sexual Animal/fisiologia , EstereoisomerismoRESUMO
A survey of linalool enantiomers in kiwifruit (Actinidia) flowers was conducted to determine their potential as sources of these valuable floral fragrances, and revealed a wide range of enantiomeric ratios. While flowers of A. polygama and A. chrysantha contained almost exclusively one enantiomer, most species contained significant amounts of both (R) and (S) isomers. In some species enantiomeric ratios of floral linalool differed between genotypes, full siblings, and in one case clones, and ratios changed from year to year as well as diurnally. Enantioselective biosynthesis of the linalool-derived furanoid and pyranoid linalool oxides was examined in flowers of an A. chrysantha and an A. polygama genotype. The flowers of both species produced almost exclusively (S)-linalool. A. chrysantha flowers incubated with rac-d5-linalool preferentially processed the (S)-isomer through to the linalool oxides. However, the A. polygama flowers were less discriminatory in their use of rac-d5-linalool and processed significant quantities of d5-(R)-linalool as well.
Assuntos
Actinidia/química , Flores/química , Monoterpenos/química , Actinidia/genética , Monoterpenos Acíclicos , Genótipo , Espectrometria de Massas , Especificidade da Espécie , EstereoisomerismoRESUMO
* High-temperature, low-light (HTLL) treatment of 35S:PAP1 Arabidopsis thaliana over-expressing the PAP1 (Production of Anthocyanin Pigment 1) gene results in reversible reduction of red colouration, suggesting the action of additional anthocyanin regulators. High-performance liquid chromatography (HPLC), liquid chromatography mass spectrometry (LCMS) and Affimetrix-based microarrays were used to measure changes in anthocyanin, flavonoids, and gene expression in response to HTLL. * HTLL treatment of control and 35S:PAP1 A. thaliana resulted in a reversible reduction in the concentrations of major anthocyanins despite ongoing over-expression of the PAP1 MYB transcription factor. Twenty-one anthocyanins including eight cis-coumaryl esters were identified by LCMS. The concentrations of nine anthocyanins were reduced and those of three were increased, consistent with a sequential process of anthocyanin degradation. Analysis of gene expression showed down-regulation of flavonol and anthocyanin biosynthesis and of transport-related genes within 24 h of HTLL treatment. No catabolic genes up-regulated by HTLL were found. * Reductions in the concentrations of anthocyanins and down-regulation of the genes of anthocyanin biosynthesis were achieved by environmental manipulation, despite ongoing over-expression of PAP1. Quantitative PCR showed reduced expression of three genes (TT8, TTG1 and EGL3) of the PAP1 transcriptional complex, and increased expression of the potential transcriptional repressors AtMYB3, AtMYB6 and AtMYBL2 coincided with HTLL-induced down-regulation of anthocyanin biosynthesis. * HTLL treatment offers a model system with which to explore anthocyanin catabolism and to discover novel genes involved in the environmental control of anthocyanins.
Assuntos
Arabidopsis/fisiologia , Meio Ambiente , Pigmentação , Folhas de Planta/fisiologia , Fatores de Transcrição/metabolismo , Antocianinas/química , Antocianinas/metabolismo , Arabidopsis/genética , Arabidopsis/efeitos da radiação , Proteínas de Arabidopsis , Biomassa , Análise por Conglomerados , Flavonóis/química , Flavonóis/metabolismo , Regulação da Expressão Gênica de Plantas , Genes de Plantas , Genes Reguladores , Glicosídeos/química , Glicosídeos/metabolismo , Luz , Proteínas Associadas a Pancreatite , Pigmentação/efeitos da radiação , Folhas de Planta/efeitos da radiação , Temperatura , Fatores de Transcrição/genéticaRESUMO
Dietary antioxidants are often defined by in vitro measures of antioxidant activity. Such measures are valid indicators of the antioxidant potential, but provide little evidence of activity as a dietary antioxidant. This study was undertaken to assess the in vivo antioxidant efficacy of a berry fruit extract by measuring biomarkers of oxidative damage to protein (carbonyls), lipids (malondialdehyde), and DNA (8-oxo-2'-deoxyguanosine urinary excretion) and plasma antioxidant status (antioxidant capacity, vitamin E) in rats when fed basal diets containing fish and soybean oils, which are likely to generate different levels of oxidative stress. Boysenberry (Rubus loganbaccus x baileyanus Britt) extract was used as the dietary antioxidant. The basal diets (chow, synthetic/soybean oil, or synthetic/fish oil) had significant effects on the biomarkers of oxidative damage and antioxidant status, with rats fed the synthetic/fish oil diet having the lowest levels of oxidative damage and the highest antioxidant status. When boysenberry extract was added to the diet, there was little change in 8-oxo-2'-deoxyguanosine excretion in urine, oxidative damage to proteins decreased, and plasma malondialdehyde either increased or decreased depending on the basal diet. This study showed that boysenberry extract functioned as an in vivo antioxidant and raised the antioxidant status of plasma while decreasing some biomarkers of oxidative damage, but the effect was highly modified by basal diet. Our results are further evidence of complex interactions among dietary antioxidants, background nutritional status as determined by diet, and the biochemical nature of the compartments in which antioxidants function.
Assuntos
Antioxidantes/farmacologia , Dieta , Frutas/química , Estresse Oxidativo/efeitos dos fármacos , Extratos Vegetais/farmacologia , Rosaceae/química , Animais , Dano ao DNA/efeitos dos fármacos , Desoxiadenosinas/urina , Masculino , Malondialdeído/sangue , Ratos , Ratos Sprague-Dawley , Vitamina E/sangue , Aumento de PesoRESUMO
Lilac alcohol epoxide (2-(5-methyl-5-(oxiran-2-yl)-tetrahydrofuran-2-yl)propan-1-ol), a previously unreported monoterpene, was identified in the solvent extract of the flowers of seven Actinidia arguta genotypes. The diastereomeric lilac alcohol epoxides co-occurred with the lilac aldehydes and alcohols. Another compound, the lilac diol (2-(5-(1-hydroxyethyl)-5-methyl-tetrahydrofuran-2-yl)propan-1-ol) was synthesised as part of our efforts to identify the lilac alcohol epoxide.
Assuntos
Actinidia/química , Álcoois/química , Compostos de Epóxi/química , Óxido de Etileno/análogos & derivados , Flores/química , Furanos/química , Monoterpenos/química , Propanóis/química , Monoterpenos Acíclicos , Álcoois/análise , Cromatografia Líquida de Alta Pressão , Compostos de Epóxi/análise , Óxido de Etileno/química , Óxido de Etileno/isolamento & purificação , Furanos/isolamento & purificação , Estrutura Molecular , Propanóis/isolamento & purificaçãoRESUMO
Two syntheses of deuterated gamma-lactones for use as internal standards in stable isotope dilution assays (SIDA) were developed. [2,2,3,3-2H4]-gamma-Octa-, -gamma-deca-, and -gamma-dodecalactones with >89% deuterium incorporation were prepared in 27, 17, and 19% overall yields, respectively, by the reduction of a doubly protected hydroxypropiolic acid with deuterium gas. [3,3,4-2H3]-gamma-Octa- and -gamma-dodecalactones were prepared in 6 and 23% yields with >92% deuterium incorporation by the free radical addition of 2-iodoacetamide to [1,1,2-2H3]-1-hexene and [1,1,2-2H3]-1-decene, respectively. Reaction yields were highly dependent upon the purity of the 1-alkene starting material. The deuterated gamma-lactones were evaluated as internal standards for SIDA.
Assuntos
Deutério , Técnicas de Diluição do Indicador , Lactonas/química , Marcação por IsótopoRESUMO
Flavor is an important quality trait of fruit and a target for improvement through plant breeding. Eighty-nine flavor volatiles from 240 apple (Malus domestica) genotypes from a highly diverse breeding population were measured by headspace gas chromatography-mass spectrometry (GC-MS) over 2 years. Heritabilities and phenotypic and genetic correlations were calculated for 23 flavor volatiles. Genetic correlations showed coinheritance of five groups of volatiles, ethyl esters, alcohols and alpha-farnesene, propyl and butyl esters, propanoate and 2-methylbutanoate esters, and acetate esters, consistent with our knowledge of volatile biosynthesis in apple. This work demonstrates a genetic structure underlying the highly variable volatile profiles observed for apple fruit and the potential of GC-MS volatile profiling for the genetic analysis of aroma volatiles in genetically diverse populations.
Assuntos
Frutas/química , Frutas/genética , Genótipo , Malus/genética , Fenótipo , Compostos Orgânicos Voláteis/análise , Cruzamento , Cromatografia Gasosa-Espectrometria de Massas , Odorantes/análise , Especificidade da Espécie , Paladar , VolatilizaçãoRESUMO
Volatile flavor compounds from the fruit of the progeny of two apple (Malus x domestica) cultivars with distinctive flavor and volatile profiles, 'Royal Gala' and 'Granny Smith', were measured by headspace gas chromatography-mass spectrometry over two fruiting seasons. Principal component analysis separated the volatile profiles into two groups according to the amounts produced of butyl, 2-methybutyl, pentyl, and hexyl acetates and of ethyl butanoate, butanol, 2-methylbutanol, and hexanol. Fruit containing the four acetate esters clustered with the 'Royal Gala' parent and were scored more similar to 'Royal Gala' than to "Granny Smith' in flavor. Fruit clustering with the 'Granny Smith' parent contained higher levels of ethyl butanoate and alcohols. Levels of acetate esters correlated to levels of their alcohol precursors, and control of this trait segregated in Mendelian fashion. The locus was mapped to the top of 'Royal Gala' linkage group 2 close to the Rvi4 (Vh4) locus for resistance to Venturia inaequalis , the causal agent of apple scab.