Project description:Experimental research on the effects of abiotic stress over grapevine has mainly focused on water shortage. The adaptation of plants to stress is a complex response triggered by cascades of molecular networks involved in stress perception, signal transduction, and the expression of specific stress-related genes and metabolites. Approaches such as array-based transcript profiling allow assessing the expression of thousands of genes in control and stress tissues. Gene expression upon acute (heat and light) and steady (drought) individual stresses and field conditions were compared in two grapevine (Vitis vinifera L.) varieties, Trincadeira (TR) and Touriga Nacional (TN).
Project description:Oxidative stress can arise when in vitro propagated plants developed under low light conditions are exposed to high light during transfer to ex vitro conditions. In such a situation, among the many potential stresses to which the transferred plant can be exposed, oxidative stress is commonly experienced, most likely brought about by absorption of light energy in excess of that required for very low levels of photosynthetic metabolism. In vitro propagated grapevine when transferred to ex vitro conditions with a 4 fold increase in PPFD shows an initial inhibition of PET accompanied by an accumulation of H2O2, suggesting a signal for the upregulation in gene expression and antioxidant enzyme activity, which peaked at 48h after transfer of in vitro grapevine to ex vitro growing conditions. When in vitro propagated plants are exposed to high light upon transfer to ex vitro oxidative stress symptoms occur. To determine whether the underlying pathways activated at the transfer of in vitro grapevine to ex vitro conditions reflect the processes occurring upon light stress we used microarrays. Leaves were harvested from in vitro grown plants immediately prior to transfer to ex vitro condition and 48h after transfer to compare gene expression before and after exposure of these plants to the high light conditions typical of ex vitro growth.
Project description:Plants regenerated from tissue culture frequently show somaclonal variation. In this study we compared the transcriptomic and epigenetic state of embryogenic callus of grapevine with leaves from mature grapevine plants. In particular, we focussed on the expression of transposable elements and changes in siRNA abundance and genome-wide methylation in these tissues.
Project description:Plants regenerated from tissue culture frequently show somaclonal variation. In this study we compared the transcriptomic and epigenetic state of embryogenic callus of grapevine with leaves from mature grapevine plants. In particular, we focussed on the expression of transposable elements and changes in siRNA abundance and genome-wide methylation in these tissues.
Project description:Plants regenerated from tissue culture frequently show somaclonal variation. In this study we compared the transcriptomic and epigenetic state of embryogenic callus of grapevine with leaves from mature grapevine plants. In particular, we focussed on the expression of transposable elements and changes in siRNA abundance and genome-wide methylation in these tissues.
Project description:Background: Global climate change, in particular the entailed predicted temperature increase, will noticeably affect plants vegetative and reproductive development. High temperatures alter the composition of the grapevine fruit, one of the most important fruits produced worldwide. This is leading to variable yield and quality, already observed in many growing regions in recent years. However, physiological processes underlying temperature response and tolerance of the grapevine fruit have hardly been investigated. Currently, all studies on fleshy fruits investigating their abiotic stress response on a molecular level were conducted during the day but possible night-specific variations were overlooked. The present study explores the grapevine fruit transcriptomic response at different developmental stages upon heat stress at day and night. Methodology/Principal Results: Short heat stresses (2 h) were applied at day and night to vines bearing clusters sequentially ordered according to the developmental stages along their vertical axis. The recently proposed microvine model was grown in climatic chambers in order to circumvent common constraints and biases introduced in field experiments with perennial vines. Post-véraison berry heterogeneity inside clusters was evaded upon constituting homogenous batches following organic acid and sugar measurements on individual berries. A whole genome transcriptomic approach was subsequently conducted using NimbelGen® 090918 12X microarrays (30K). Results revealed important differences in heat stress responsive pathways according to day or night treatment, in particular regarding genes within phenylpropanoid metabolism. Precise distinction of post-véraison stages led to a stage-specific detection of anthocyanin-related transcripts repressed by heat. Important modifications in cell wall-related processes as well as indications for a heat-induced delay of ripening and sugar accumulation were observed at véraison and reversed in later stages. Conclusion: This first day - night study on heat stress adaption of the grapevine berry shows that the transcriptome of fleshy fruits is differentially affected by abiotic stress at night. The present results emphasize the necessity to include different developmental stages and especially different time points in transcriptomic studies.
Project description:Oxidative stress can arise when in vitro propagated plants developed under low light conditions are exposed to high light during transfer to ex vitro conditions. In such a situation, among the many potential stresses to which the transferred plant can be exposed, oxidative stress is commonly experienced, most likely brought about by absorption of light energy in excess of that required for very low levels of photosynthetic metabolism. In vitro propagated grapevine when transferred to ex vitro conditions with a 4 fold increase in PPFD shows an initial inhibition of PET accompanied by an accumulation of H2O2, suggesting a signal for the upregulation in gene expression and antioxidant enzyme activity, which peaked at 48h after transfer of in vitro grapevine to ex vitro growing conditions. When in vitro propagated plants are exposed to high light upon transfer to ex vitro oxidative stress symptoms occur. To determine whether the underlying pathways activated at the transfer of in vitro grapevine to ex vitro conditions reflect the processes occurring upon light stress we used microarrays.
Project description:Background: Global climate change, in particular the entailed predicted temperature increase, will noticeably affect plants vegetative and reproductive development. High temperatures alter the composition of the grapevine fruit, one of the most important fruits produced worldwide. This is leading to variable yield and quality, already observed in many growing regions in recent years. However, physiological processes underlying temperature response and tolerance of the grapevine fruit have hardly been investigated. Currently, all studies on fleshy fruits investigating their abiotic stress response on a molecular level were conducted during the day but possible night-specific variations were overlooked. The present study explores the grapevine fruit transcriptomic response at different developmental stages upon heat stress at day and night. Methodology/Principal Results: Short heat stresses (2 h) were applied at day and night to vines bearing clusters sequentially ordered according to the developmental stages along their vertical axis. The recently proposed microvine model was grown in climatic chambers in order to circumvent common constraints and biases introduced in field experiments with perennial vines. Post-véraison berry heterogeneity inside clusters was evaded upon constituting homogenous batches following organic acid and sugar measurements on individual berries. A whole genome transcriptomic approach was subsequently conducted using NimbelGen® 090918 12X microarrays (30K). Results revealed important differences in heat stress responsive pathways according to day or night treatment, in particular regarding genes within phenylpropanoid metabolism. Precise distinction of post-véraison stages led to a stage-specific detection of anthocyanin-related transcripts repressed by heat. Important modifications in cell wall-related processes as well as indications for a heat-induced delay of ripening and sugar accumulation were observed at véraison and reversed in later stages. Conclusion: This first day - night study on heat stress adaption of the grapevine berry shows that the transcriptome of fleshy fruits is differentially affected by abiotic stress at night. The present results emphasize the necessity to include different developmental stages and especially different time points in transcriptomic studies. A total of 12 samples were analyzed representing three berry developmental stages (two after the onset of ripening, one during green growth). At each stage, heat stress was applied at day and night. Controls and treated berry samples were drawn in triplicates (two in duplicates) at day and at night on the microvine dwarf (Dwarf Rapid Cycling and Continous Flowering; DRCF) gibberellin-insensitive (GAI) mutant.
Project description:Drought stress dramatically affects the growth and development of grapevine (Vitis vinifera) in many areas of the world, and identifying the mechanisms responsible for drought stress responses is therefore of great interest. The transcription factor, VlbZIP30 has been reported to enhance drought resistance in grapevine, however, the regulatory mechanisms mediated by VlbZIP30 remain poorly understood. Here, we performed chromatin immunoprecipitation (ChIP)-seq and RNA-seq analyses to identify the direct VlbZIP30 target genes at a genome-wide scale. The ChIP-seq analysis determined that VlbZIP30 binds to DNA sequences containing an ACGTG core motif, termed a G-box. By combining the ChIP-seq and RNA-seq results, we identified 48 VlbZIP30-induced target genes, related mainly to the gene ontology (GO) terms: nucleic acid-templated transcription, plant hormone and abiotic stimulus. Through ChIP-qPCR analysis, we confirmed that VlbZIP30 binds directly to the promoters of four of the target genes (VvNAC26, VvDHN1, VvGRAS17 and VvVQ6) containing a G-box motif. In addition, overexpression of VlbZIP30 led to less H2O2 accumulation compared with the wild type under drought conditions in both Arabidopsis thaliana and grapevine, indicating a role for VlbZIP30 in reactive oxygen species (ROS) scavenging. In summary, we report that VlbZIP30 promotes the activity of ROS scavenging by directly regulating the expression of downstream target genes, thereby conferring drought resistance. We also reveal that VlbZIP30 directly regulates the expression of a number of target genes (such as VvDHN1, VvGRAS17 and VvVQ6) to improve plant drought resistance.