A manipulation of carotenoid metabolism influence biomass partitioning and fitness in tomato.

Improving yield, nutritional value and tolerance to abiotic stress are major targets of current breeding and biotechnological approaches that aim at increasing crop production and ensuring food security. Metabolic engineering of carotenoids, the precursor of vitamin-A and plant hormones that regulate plant growth and response to adverse growth conditions, has been mainly focusing on provitamin A biofortification or the production of high-value carotenoids. Here, we show that the introduction of a single gene of the carotenoid biosynthetic pathway in different tomato cultivars induced profound metabolic alterations in carotenoid, apocarotenoid and phytohormones pathways. Alterations in isoprenoid- (abscisic acid, gibberellins, cytokinins) and non-isoprenoid (auxin and jasmonic acid) derived hormones together with enhanced xanthophyll content influenced biomass partitioning and abiotic stress tolerance (high light, salt, and drought), and it caused an up to 77% fruit yield increase and enhanced fruit's provitamin A content. In addition, metabolic and hormonal changes led to accumulation of key primary metabolites (e.g. osmoprotectants and antiaging agents) contributing with enhanced abiotic stress tolerance and fruit shelf life. Our findings pave the way for developing a new generation of crops that combine high productivity and increased nutritional value with the capability to cope with climate change-related environmental challenges.

Model-assisted identification of metabolic engineering strategies for Jatropha curcas lipid pathways.

Efficient approaches to increase plant lipid production are necessary to meet current industrial demands for this important resource. While Jatropha curcas cell culture can be used for in vitro lipid production, scaling up the system for industrial applications requires an understanding of how growth conditions affect lipid metabolism and yield. Here we present a bottom-up metabolic reconstruction of J. curcas supported with labeling experiments and biomass characterization under three growth conditions. We show that the metabolic model can accurately predict growth and distribution of fluxes in cell cultures and use these findings to pinpoint energy expenditures that affect lipid biosynthesis and metabolism. In addition, by using constraint-based modeling approaches we identify network reactions whose joint manipulation optimizes lipid production. The proposed model and computational analyses provide a stepping stone for future rational optimization of other agronomically relevant traits in J. curcas.

Towards model-driven characterization and manipulation of plant lipid metabolism.

Plant lipids have versatile applications and provide essential fatty acids in human diet. Therefore, there has been a growing interest to better characterize the genetic basis, regulatory networks, and metabolic pathways that shape lipid quantity and composition. Addressing these issues is challenging due to context-specificity of lipid metabolism integrating environmental, developmental, and tissue-specific cues. Here we systematically review the known metabolic pathways and regulatory interactions that modulate the levels of storage lipids in oilseeds. We argue that the current understanding of lipid metabolism provides the basis for its study in the context of genome-wide plant metabolic networks with the help of approaches from constraint-based modeling and metabolic flux analysis. The focus is on providing a comprehensive summary of the state-of-the-art of modeling plant lipid metabolic pathways, which we then contrast with the existing modeling efforts in yeast and microalgae. We then point out the gaps in knowledge of lipid metabolism, and enumerate the recent advances of using genome-wide association and quantitative trait loci mapping studies to unravel the genetic regulations of lipid metabolism. Finally, we offer a perspective on how advances in the constraint-based modeling framework can propel further characterization of plant lipid metabolism and its rational manipulation.

Spit and venom from scytodes spiders: a diverse and distinct cocktail.

Spiders from the family Scytodidae have a unique prey capturing technique: they spit a zig-zagged silken glue to tether prey to a surface. Effectiveness of this sticky mixture is based on a combination of contraction and adhesion, trapping prey until the spider immobilizes it by envenomation and then feeds. We identify components expressed in Scytodes thoracica venom glands using combined transcriptomic and proteomic analyses. These include homologues of toxic proteins astacin metalloproteases and potentially toxic proteins including venom allergen, longistatin, and translationally controlled tumor protein (TCTP). We classify 19 distinct groups of candidate peptide toxins; 13 of these were detected in the venom, making up 35% of the proteome. Six have significant similarity to toxins from spider species spanning mygalomorph and nonhaplogyne araneomorph lineages, suggesting their expression in venom is phylogenetically widespread. Twelve peptide toxin groups have homologues in venom gland transcriptomes of other haplogynes. Of the transcripts, approximately 50% encode glycine-rich peptides that may contribute to sticky fibers in Scytodes spit. Fifty-one percent of the identified venom proteome is a family of proteins that is homologous to sequences from Drosophila sp. and Latrodectus hesperus with uncharacterized function. Characterization of these components holds promise for discovering new functional activity.

Lipid profile of in vitro oil produced through cell culture of Jatropha curcas.

Recent increases in energy demands as a consequence of population growth and industrialization, and pollution caused during the extraction and combustion of fossil fuel sources have driven the development of new energy sources that do not cause pollution and are inexpensive and renewable. Consequently, it is necessary to develop alternative ways of generating biofuels that put less pressure on agricultural lands and water supplies, and ensure ecosystems conservation. In order to achieve the proposed goals related to energetic coverage and independence, several approaches have been developed, including biodiesel production using vegetal oils as feedstock. The aim of the current research project was to apply a nonconventional bioprocess for in vitro biomass and oil production of Jatropha curcas, for assessing different J. curcas varieties, where seed tissue was isolated and used for callus induction. Once friable callus was obtained, cell suspension cultures were established. The cell viability, fatty acid content, and characteristics were used to select the most promising cell line according to its fatty acid profile and ability to grow and develop under in vitro conditions. Oil produced by cell suspension culture of the Jatropha varieties studied was extracted and characterized by GC/MS. Differences encountered among Jatropha varieties were related to their fatty acid profiles, oil content (% on dry basis), and cell viability measurements (%).