Abscisic acid inhibits germination of Striga seeds and is released by them likely as a rhizospheric signal supporting host infestation.

Seeds of the root parasitic plant Striga hermonthica undergo a conditioning process under humid and warm environments before germinating in response to host-released stimulants, particularly strigolactones (SLs). The plant hormone abscisic acid (ABA) regulates different growth and developmental processes, and stress response; however, its role during Striga seed germination and early interactions with host plants is under-investigated. Here, we show that ABA inhibited Striga seed germination and that hindering its biosynthesis induced conditioning and germination in unconditioned seeds, which was significantly enhanced by treatment with the SL analog rac-GR24.

Reducing PHYTOENE SYNTHASE activity fine-tunes the abundance of a cis-carotene-derived signal that regulates the PIF3/HY5 module and plastid biogenesis.

PHYTOENE SYNTHASE (PSY) is a rate-limiting enzyme catalysing the first committed step of carotenoid biosynthesis, and changes in PSY gene expression and/or protein activity alter carotenoid composition and plastid differentiation in plants. Four genetic variants of PSY (psy-4, psy-90, psy-130, and psy-145) were identified using a forward genetics approach that rescued leaf virescence phenotypes and plastid abnormalities displayed by the Arabidopsis CAROTENOID ISOMERASE (CRTISO) mutant ccr2 (carotenoid and chloroplast regulation 2) when grown under a shorter photoperiod. The four non-lethal mutations affected alternative splicing, enzyme-substrate interactions, and PSY:ORANGE multi-enzyme complex binding, constituting the dynamic post-transcriptional fine-tuning of PSY levels and activity without changing localization to the stroma and protothylakoid membranes.

Biomimetic Mineralization for Smart Biostimulant Delivery and Crop Micronutrients Fortification.

Sustainable and precise fortification practices are necessary to ensure food security for the increasing human population. Precision agriculture aims to minimize the use of fertilizers and pesticides by developing smart materials for real-life agricultural practices. Here, we show that biomimetic mineralization can be efficiently employed to encapsulate and controllably release plant biostimulants (MiZax-3) to improve the quality and yield of capsicum () crops in field experiments.

Carotenoid metabolism: New insights and synthetic approaches.

Carotenoids are well-known isoprenoid pigments naturally produced by plants, algae, photosynthetic bacteria as well as by several heterotrophic microorganisms. In plants, they are synthesized in plastids where they play essential roles in light-harvesting and in protecting the photosynthetic apparatus from reactive oxygen species (ROS). Carotenoids are also precursors of bioactive metabolites called apocarotenoids, including vitamin A and the phytohormones abscisic acid (ABA) and strigolactones (SLs).

The Arabidopsis D27-LIKE1 is a cis/cis/trans-β-carotene isomerase that contributes to Strigolactone biosynthesis and negatively impacts ABA level.

The enzyme DWARF27 (D27) catalyzes the reversible isomerization of all-trans- into 9-cis-β-carotene, initiating strigolactone (SL) biosynthesis. Genomes of higher plants encode two D27-homologs, D27-like1 and -like2, with unknown functions. Here, we investigated the enzymatic activity and biological function of the Arabidopsis D27-like1.

Screening for apocarotenoid plant growth regulators in Arabidopsis.

Apocarotenoids are bioactive metabolites found in animals, fungi and plants. Several carotenoid-derived compounds, apocarotenoids, were recently identified as new growth regulators in different plant species. Here, we introduce basic chemical screening methods, using a model plant, Arabidopsis thaliana, to elucidate the function of bioactive apocarotenoids in determining plant phenotypic traits.

Characterizing cytochrome P450 enzymes involved in plant apocarotenoid metabolism by using an engineered yeast system.

Cytochrome P450 enzymes (CYPs) are involved in metabolic steps that provide structural diversity during the biosynthesis of carotenoids and their oxidative cleavage products called apocarotenoids. Recent studies on bioactive apocarotenoids in plants revealed the necessity of performing further research to uncover the function of novel CYP enzymes that might be involved in apocarotenoid metabolism. We describe a series of in-vitro methods to characterize plant CYPs that metabolize apocarotenoids, using a specific Saccharomyces cerevisiae strain, WAT11, engineered to express a CYP redox partner, Arabidopsis thaliana NADPH-P450 reductase 1 (ATR1).

Purification and use of carotenoid standards to quantify cis-trans geometrical carotenoid isomers in plant tissues.

Reverse-phase high-performance liquid chromatography (HPLC) is a preferred method used to identify and quantify carotenoids. Here, we describe a straightforward, reliable, and cost-effective protocol to purify and develop individual carotenoid standards for absolute quantification of carotenoids, including selected cis-trans (geometric) isomers. Analytical techniques to extract, purify and collect individual carotenoids using an HPLC system equipped with a Diode Array Detector (DAD) and fraction collector are described.

Ultra-high performance liquid chromatography-mass spectrometry analysis of plant apocarotenoids.

Apocarotenoids (APOs) are a class of carotenoid oxidation products with high structural and functional diversity. Apart from serving as precursors of phytohormones, fungal pheromones and vitamin A, several APOs act as signaling molecules involved in stress response and growth as regulators in plants. To comprehensively profile plant APOs, we established an improved ultra-high performance liquid chromatography-hybrid quadrupole-Orbitrap mass spectrometer (UHPLC-Q-Orbitrap MS) analytical platform.

Plant apocarotenoids: from retrograde signaling to interspecific communication.

Carotenoids are isoprenoid compounds synthesized by all photosynthetic and some non-photosynthetic organisms. They are essential for photosynthesis and contribute to many other aspects of a plant's life. The oxidative breakdown of carotenoids gives rise to the formation of a diverse family of essential metabolites called apocarotenoids.

A -carotene derived apocarotenoid regulates etioplast and chloroplast development.

Carotenoids are a core plastid component and yet their regulatory function during plastid biogenesis remains enigmatic. A unique carotenoid biosynthesis mutant, (), that has no prolamellar body (PLB) and normal PROTOCHLOROPHYLLIDE OXIDOREDUCTASE (POR) levels, was used to demonstrate a regulatory function for carotenoids and their derivatives under varied dark-light regimes. A forward genetics approach revealed how an epistatic interaction between a mutant () and blocked the biosynthesis of specific -carotenes and restored PLB formation in etioplasts.

cis/trans Carotenoid Extraction, Purification, Detection, Quantification, and Profiling in Plant Tissues.

Reverse phase high-performance liquid chromatography (HPLC) is the method of choice used in biological, health, and food research to identify, quantify, and profile carotenoid species. The identification and quantification of cis- and/or trans-carotene and xanthophyll isomers in plant tissues can be affected by the method of sample preparation and extraction, as well as the HPLC column chemistry and the solvent gradient. There is a high degree of heterogeneity in existing methods in terms of their ease, efficiency, and accuracy.

cis-carotene biosynthesis, evolution and regulation in plants: The emergence of novel signaling metabolites.

Carotenoids are isoprenoid pigments synthesised by plants, algae, photosynthetic bacteria as well as some non-photosynthetic bacteria, fungi and insects. Abundant carotenoids found in nature are synthesised via a linear route from phytoene to lycopene after which the pathway bifurcates into cyclised α- and β-carotenes. Plants evolved additional steps to generate a diversity of cis-carotene intermediates, which can accumulate in fruits or tissues exposed to an extended period of darkness.

Manipulating the Biosynthesis of Bioactive Compound Alkaloids for Next-Generation Metabolic Engineering in Opium Poppy Using CRISPR-Cas 9 Genome Editing Technology.

Clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated9 (Cas9) endonuclease system is a powerful RNA-guided genome editing tool. CRISPR/Cas9 has been well studied in model plant species for targeted genome editing. However, few studies have been reported on plant species without whole genome sequence information.