Impact of phenylpropanoid compounds on heat stress tolerance in carrot cell cultures

The phenylpropanoid and flavonoid families include thousands of specialized metabolites that influence a wide range of processes in plants, including seed dispersal, auxin transport, photoprotection, mechanical support and protection against insect herbivory. Such metabolites play a key role in the protection of plants against abiotic stress, in many cases through their well-known ability to inhibit the formation of reactive oxygen species (ROS). However, the precise role of specific phenylpropanoid and flavonoid molecules is unclear. We therefore investigated the role of specific anthocyanins (ACs) and other phenylpropanoids that accumulate in carrot cells cultivated in vitro, focusing on their supposed ability to protect cells from heat stress. First we characterized the effects of heat stress to identify quantifiable morphological traits as markers of heat stress susceptibility. We then fed the cultures with precursors to induce the targeted accumulation of specific compounds, and compared the impact of heat stress in these cultures and unfed controls. Data modeling based on Projection to Latent Structures (PLS) regression revealed that metabolites containing coumaric or caffeic acid, including ACs, correlate with less heat damage. Further experiments suggested that one of the cellular targets damaged by heat stress and protected by these metabolites is the actin microfilament cytoskeleton

Towards a scientific interpretation of the terroir concept: plasticity of the grape berry metabolome

BACKGROUND: The definition of the terroir concept is one of the most debated issues in oenology and viticulture. The dynamic interaction among diverse factors including the environment, the grapevine plant and the imposed viticultural techniques means that the wine produced in a given terroir is unique. However, there is an increasing interest to define and quantify the contribution of individual factors to a specific terroir objectively. Here, we characterized the metabolome and transcriptome of berries from a single clone of the Corvina variety cultivated in seven different vineyards, located in three macrozones, over a 3-year trial period. RESULTS: To overcome the anticipated strong vintage effect, we developed statistical tools that allowed us to identify distinct terroir signatures in the metabolic composition of berries from each macrozone, and from different vineyards within each macrozone. We also identified non-volatile and volatile components of the metabolome which are more plastic and therefore respond differently to terroir diversity. We observed some relationships between the plasticity of the metabolome and transcriptome, allowing a multifaceted scientific interpretation of the terroir concept. CONCLUSIONS: Our experiments with a single Corvina clone in different vineyards have revealed the existence of a clear terroir-specific effect on the transcriptome and metabolome which persists over several vintages and allows each vineyard to be characterized by the unique profile of specific metabolites.Andrea Anesi, Matteo Stocchero, Silvia Dal Santo, Mauro Commisso, Sara Zenoni, Stefania Ceoldo, Giovanni Battista Tornielli, Tracey E. Siebert, Markus Herderich, Mario Pezzotti and Flavia Guzz

Metabolomics of Daucus carota cultured cell lines under stressing conditions reveals interactions between phenolic compounds

A metabolomic approach followed by principal components and partial least square analysis was used for investigating the effect of environmental factors on two Daucus carota L. cv. Flakkese cell lines (R3M and R4G), selected for their ability to produce anthocyanins in the light and the dark, respectively. A positive correlation between total anthocyanin, hydroxycinnamic and hydroxybenzoic acid accumulation was found in both lines. Furthermore, the experimental design and the combination of biochemical and statistical analyses allowed us to unravel complex relationships between environmental factors and phenylpropanoid composition. Among these, the induction bymechanical stress of overproduction of all anthocyanins, hydroxycinnamic and hydroxybenzoic acids except sinapic acid derivatives, whose accumulation was inhibited

The modification of phenylpropanoid profile affects sensitivity to heat stress in cell cultures of Daucus carota

Precursors and inhibitors of the phenylpropanoid pathway were used for modifying the level of specific secondary metabolites in R3M carrot cell culture, a red pigmented line characterised by the production of cyanidin and hydroxycinnamic acid (HCA) derivatives, in order to evaluate the effects of profile modification on heat stress response. The heat treatment (1h at 44 \ub0C) caused the appearance of cytoplasmic patches surrounded by endoplasmic reticulum, the arrest of endocellular movements, and a strong reduction of the viable cell number, since the patched cells were committed to slow cell death. Cytochalasin D, an anti-microfilament agent, caused the formation of structures similar to the heat-induced patches at specific concentrations. These results suggest that the heat stress-determined microfilament damages caused the formation of cytoplasmic patches, structures which anticipate programmed cell death. Feeding R3M cells with dihydroquercetin (a precursor of cyanidin) and HCAs before the heat treatment caused an increase in acylated anthocyanins and HCA derivatives and a reduction in the number of patched and dead cells. The supply of piperonilic acid, an inhibitor of the biosynthesis of p-coumaric acid (an intermediate of anthocyanin biosynthesis and substrate of their acylation) caused a decrease in the level of specific phenylpropanoids and an increase in the number of cells with stressed phenotype. These data suggest that specific phenylpropanoids can play a protective role against heat stress even though the detailed analysis of the correlation between the level of single metabolites and stress response is in progress