Search

The in vivo headspace extraction of volatile organic compounds from Micro-Tom tomato flowers was investigated using multiple solid phase microextraction (SPME) fibers of different properties to maximize the extraction selectivity for a nontargeted analysis. The three fibers used in this work were polydimethylsiloxane (PDMS), PDMS/divinylbenzene (DVB), and carboxen (CAR)/PDMS. Two sources for tomato flowers were used: Micro-Tom wild type (WT) and transgenic Micro-Tom overexpressing the carotenoid cleavage deoxygenase 1 gene. Gas chromatography-mass spectrometry (GC-MS) results demonstrated that the largest amounts of volatile organic compounds (VOCs) were observed with the PDMS/DVB fiber for both wild type and transgenic plants, but the CAR/PDMS and PDMS fibers contributed to the detection of selective compounds. Data revealed the presence of 45 VOCs from transgenic plants and 35 from the wild type when all three fibers were used together. Of the totalVOCs identified, 30 were common to both types of plants, but 15 were specific to the transgenic and 5 to the wild type plants. The compounds identified from Micro-Tom flowers were mainly monocyclic and bicyclic monoterpenes and sesquiterpenes, with one alkyl benzene compound. The bicyclic monoterpenes, (1R)-α-pinene, (1S)-α-pinene, and β-pinene, were found to be the most abundant molecules present in both wild type and transgenic plants. The overall advantage of maximizing the discovery of VOCs based on the selectivity differences with three SPME fibers was evident. Such a benefit is important in the nontargeted analysis of transgenic plants for detecting the production of unexpected compounds. Key words: headspace, gas chromatography-mass spectrometry (GC-MS), transgenic, volatile, insecticide. L'extraction in vivo espace de tete de composes organiques volatils (COVs) provenant de fleurs de tomates a ete etudiee en utilisant plusieurs (microextraction en phase solide, SPME) ayant des proprietes differentes afin de maximiser la selectivite d'extraction pour une analyse non ciblee. Les trois fibres utilisees dans ce travail sont le polydimethylsiloxane (PDMS), le PDMS/divinylbenzene (DVB) et le carboxen (CAR)/PDMS. Deux sources pour les fleurs de tomates ont ete utilisees: Micro-Tom de type sauvage (WT) et transgenique, sur-exprimant le gene CCD1. Les resultats de GC-MS ont demontre que les plus grandes quantites de COVs ont ete observees avec les fibres de DVB/PDMS pour les plantes de type sauvage comme pour les plantes transgeniques, mais les fibres RCA/PDMS et PDMS ont contribue a la detection de composes selectifs. Les donnees ont revele la presence de 45 COV dans les plantes transgeniques et 35 dans les plantes de type sauvage lorsque les trois fibres ont ete utilisees ensemble. Sur le total des composes organiques volatils identifies, 30 sont communs aux deux types de plantes, mais 15 etaient specifiques aux plantes transgeniques et 5 aux plantes de type sauvage. Les composes identifies a partir de fleurs Micro-Tom etaient essentiellement des monoterpenes et des sesquiterpenes, et un compose de benzene d'alkyle. Les monoterpenes, (1R)-α-pinene, α-pinene et le β-pinene etaient les molecules les plus abondantes a la fois dans les plantes de type sauvage et les plantes transgeniques. L'avantage de la maximisation de la decouverte de composes organiques volatils a partir de differences de selectivite avec trois fibres SPME etait evident. Un tel avantage est important dans l'analyse non ciblee de plantes transgeniques pour la detection de composes inattendus. Mots-cles: espace de tete, GC-MS, transgenique, volatil, insecticide., Introduction Plants interact with the environment by releasing volatile organic compounds (VOCs) into the atmosphere. Plant volatiles are produced by several organs of the plant with the majority released by [...]

The current study was conducted to evaluate the effect of eight Palestinian indigenous plant essential oils (EOs) under in vitro and in vivo conditions against Botrytis cinerea Pers.: Fr., Penicillium italicum Wehmer, and Penicillium digitatum (Pers.) Sacc., three common postharvest pathogens of tomato and strawberry fruits. In vivo tests showed that thyme, sesame and sage EOs exhibited high antifungal activity against B. cinerea on strawberry and tomato fruits, compared with rosemary, mint and eucalyptus. In vitro agar, disk-diffusion tests showed that B. cinerea, P. digitatum and P. italicum mycelium growth was completely inhibited when treated with clove and sage EOs caused 50% inhibition of B. cinerea and P. italicum mycelium growth. Fruit decay and fruit quality index values measured in total soluble solids and fruit flesh firmness showed that EO coated strawberries had significantly less fruit decaying and ripping compared to control, while EO coated tomatoes showed no significant difference compared to control. EO constituents fall into different chemical classes, including sterols, caffeoylquinic acids, flavonoids, terpenoids, coumarins, and acetylenes. Chemical analysis of the EO preparations using gas chromatography-mass spectrometry determined that the main components in sesame oil were octadecenoic acid-(56%) and hexadecanoic acid (26%), while clove oil consisted of eugenol (53%). In the other EOs, the principal compounds were: menthol (44% in mint oil), eucalyptol (37% in sage oil), while bornanone (18% in rosemary oil) and ?-terpinene (21% in thyme oil) were present at lower concentrations. The EO of sage plants could potentially be a useful alternative to synthetic pesticides to control post-harvest diseases and prolong the shelf life of fruit products. [ABSTRACT FROM AUTHOR]

Summary: Phytoalexin glyceollins are soybean‐specific antimicrobial compounds that are derived from the isoflavonoid pathway. They are synthesized by soybean in response to extrinsic stress such as pathogen attack or injury, thereby conferring partial resistance if synthesized rapidly at the site of infection and at the required concentration. Soybean produces multiple forms of glyceollins that result from the differential prenylation reaction catalyzed by prenyltransferases (PTs) on either the C‐2 or C‐4 carbon of a pterocarpan glycinol. The soybean genome contains 77 PT‐encoding genes (GmPTs) where at least 11 are (iso)flavonoid‐specific. Transcript accumulation of five candidates GmPTs was increased in response to Phytophthora sojae infection, suggesting their role in phytoalexin synthesis. The induced GmPTs localize to plastids and display tissue‐specific expression. We have in this study identified two additional GmPTs: an isoflavone dimethylallyltransferase 3 (IDT3); and a glycinol 2‐dimethylallyl transferase GmPT01. GmPT01 prenylates (−)‐glycinol at the C‐2 position, localizes in the plastid, and exhibits root‐specific gene expression. Furthermore, its expression is induced rapidly in response to stress, and is associated with a quantitative trait loci linked with resistance to P. sojae. Based on these results, we conclude that GmPT01 are possibly one of the loci involved in conferring partial resistance against stem and root rot disease in soybean. Significance Statement: GmPT01 is a pterocarpan 2‐dimethylallyltransferase that catalyzes the key prenylation reaction in phytoalexin glyceollin biosynthesis in soybean. The rapidly induced gene expression in response to stress and its location near a QTL linked to P. sojae resistance suggest a role of GmPT01 in partial resistance that can be utilized in resistance breeding. [ABSTRACT FROM AUTHOR]