RESUMO
Vanilla planifolia is an orchid of cultural and economic value. However, its cultivation in many tropical countries is threatened by water stress. In contrast, V. pompona is a species that is tolerant of prolonged periods of drought. Due to the need for plants' resistant to water stress, the use of hybrids of these two species is considered. Therefore, the objective of this study was to evaluate the morphological and physio-chemical responses of in vitro vanilla seedlings of the parental genotype V. planifolia, and the hybrids V. planifolia × V. pompona and V. pompona × V. planifolia, which were then exposed over five weeks to polyethylene glycol-induced water stress (-0.49 mPa). Stem and root length, relative growth rate, number of leaves and roots, stomatal conductance, specific leaf area, and leaf water content were determined. Metabolites potentially associated with the response to water stress were identified in leaves, through untargeted and targeted metabolomics. Both hybrids exhibited a smaller decrease in the morphophysiological responses compared to V. planifolia and exhibited an enrichment of metabolites such as carbohydrates, amino acids, purines, phenols, and organic acids. Hybrids of these two species are considered as a potential alternative to the traditional cultivation of vanilla to face drought in a global warming scenario.
Assuntos
Vanilla , Vanilla/metabolismo , Desidratação , Metabolômica , Plântula , CarboidratosRESUMO
Current methods for vanilla bean curing are long and reduce the enzymatic activity necessary for flavor development. High hydrostatic pressure (HHP) at 50-600 MPa was used to improve phenolic compounds formation and ß-d-glucosidase activity in vanilla beans compared with scalded beans. Phenolics were analyzed by HPLC and ß-d-glucosidase activity by spectrophotometry. Vanillin was the main phenolic and it was formed by ß-d-glucovanillin hydrolysis and vanillyl alcohol oxidation. HHP improved vanillin content and influenced ß-d-glucosidase activity. At the beginning of the curing the highest increments of vanillin were produced at 400 MPa (up to 15%), while at the end, this was observed at 50 (138%) and 600 MPa (74%). Maximum increment of up to 400% in ß-d-glucosidase activity was observed from 100 to 300 MPa, which was attributed to tissue decompartmentalization, and conformational changes induced by pressure. HHP could be used during vanilla curing to improve vanillin content and ß-d-glucosidase activity.
Assuntos
Vanilla , Benzaldeídos/metabolismo , Cromatografia Líquida de Alta Pressão , Glucosidases/metabolismo , Pressão Hidrostática , Fenóis/metabolismo , Vanilla/metabolismoRESUMO
Drought-induced water stress affects the productivity of the Vanilla planifolia Jacks. ex Andrews crop. In vitro culture technique is an effective tool for the study of water stress tolerance mechanisms. This study aimed to evaluate the morphological, physiological and biochemical response of V. planifolia under in vitro water stress conditions induced with polyethylene glycol (PEG). In vitro regenerated shoots of 2 cm in length were subjected to different concentrations of PEG 6000 (0, 1, 2 and 3% w/v) using Murashige and Skoog semi-solid culture medium. At 60 days of culture, different growth variables, dry matter (DM) content, chlorophyll (Chl), soluble proteins (SP), proline (Pro), glycine betaine (GB), stomatal index (SI) and open stomata (%) were evaluated. Results showed a reduction in growth, Chl content, SP, SI and open stomata (%) with increasing PEG concentration, whereas DM, Pro and GB contents rose with increasing PEG concentration. In conclusion, PEG-induced osmotic stress allowed describing physiological and biochemical mechanisms of response to water stress. Furthermore, the determination of compatible Pro and GB osmolytes can be used as biochemical markers in future breeding programs for the early selection of water stress tolerant genotypes.
Assuntos
Biotecnologia/métodos , Secas , Polietilenoglicóis/análise , Vanilla/metabolismo , Antioxidantes/análise , Betaína/análise , Clorofila/análise , Clorofila/química , Meios de Cultura , Genótipo , Técnicas In Vitro , Pressão Osmótica , Raízes de Plantas , Prolina/análise , Espécies Reativas de Oxigênio , ÁguaRESUMO
The fruit of Vanilla planifolia is broadly preferred by the agroindustry and gourmet markets due to its refined flavor and aroma. Peruvian Vanilla has been proposed as a possible source for genetic improvement of existing Vanilla cultivars, but, little has been done to facilitate comprehensive studies of these and other Vanilla. Here, a nuclear magnetic resonance (NMR) metabolomic platform was developed to profile for the first time the leaves - organ known to accumulate vanillin putative precursors - of V. planifolia and those of Peruvian V. pompona, V. palmarum, and V. ribeiroi, with the aim to determine metabolic differences among them. Analysis of the NMR spectra allowed the identification of thirty-six metabolites, twenty-five of which were quantified. One-way ANOVA and post-hoc Tukey test revealed that these metabolites changed significantly among species, whilst multivariate-analyses allowed the identification of malic and homocitric acids, together with two vanillin precursors, as relevant metabolic markers for species differentiation.
Assuntos
Espectroscopia de Ressonância Magnética/métodos , Metabolômica/métodos , Folhas de Planta/metabolismo , Vanilla/metabolismo , Benzaldeídos/metabolismo , Análise Multivariada , Peru , Folhas de Planta/química , Vanilla/químicaRESUMO
BACKGROUND: Upon exposure to unfavorable environmental conditions, plants need to respond quickly to maintain their homeostasis. For instance, physiological, biochemical and transcriptional changes occur during plant-pathogen interaction. In the case of Vanilla planifolia Jacks., a worldwide economically important crop, it is susceptible to Fusarium oxysporum f. sp. vanillae (Fov). This pathogen causes root and stem rot (RSR) in vanilla plants that lead to plant death. To investigate how vanilla plants, respond at the transcriptional level upon infection with Fov, here we employed the RNA-Seq approach to analyze the dynamics of whole-transcriptome changes during two-time frames of the infection. RESULTS: Analysis of global gene expression profiles upon infection by Fov indicated that the major transcriptional change occurred at 2 days post-inoculation (dpi), in comparison to 10 dpi. Briefly, the RNA-Seq analysis carried out in roots found that 3420 and 839 differentially expressed genes (DEGs) were detected at 2 and 10 dpi, respectively, as compared to the control. In the case of DEGs at 2 dpi, 1563 genes were found to be up-regulated, whereas 1857 genes were down-regulated. Moreover, functional categorization of DEGs at 2 dpi indicated that up-regulated genes are mainly associated to translation, whereas down-regulated genes are involved in cell wall remodeling. Among the translational-related transcripts, ribosomal proteins (RPs) were found increased their expression exclusively at 2 dpi. CONCLUSIONS: The screening of transcriptional changes of V. planifolia Jacks upon infection by Fov provides insights into the plant molecular response, particularly at early stages of infection. The accumulation of translational-related transcripts at early stages of infection potentially points to a transcriptional reprogramming coupled with a translational regulation in vanilla plants upon infection by Fov. Altogether, the results presented here highlight potential molecular players that might be further studied to improve Fov-induced resistance in vanilla plants.