Mimosine facilitates metallic cation uptake by plants through formation of mimosine-cation complexes

Bioinspired Metal-Ligand Networks with Enhanced Stability and Performance: Facile Preparation of Hydroxypyridinone (HOPO)-Functionalized Materials

Bioinspired hydroxypyridinone (HOPO)functionalized materials are shown to display a remarkable capacity for stability and for chelating a wide array of metal ions. This allows for the synthesis of multifunctional networks with diverse physical properties when compared to traditional catechol systems. In the present study, we report a facile, one-pot synthesis of an amino HOPO ligand and simple, scalable incorporation into PEG-acrylate based networks via active ester chemistry. This modular network approach allows for fabrication of patterned HOPO containing networks which can chelate a range of metal ions, such as transition metals (Fe3+) and lanthanides (Ho3+, Tb3+), leading to modulation of mechanical, magnetic, and fluorescent properties. Moreover, networks with tailored, heterogeneous properties can be prepared through localization of metal ion incorporation in 3-dimensions via masking techniques, creating distinctly soft, hard, magnetic, and fluorescent domains.

Mathematical modeling predicts that endemics by generalist insects are eradicated if nearly all plants produce constitutive defense

Plants with constitutive defense chemicals exist widely in nature. The phenomenon is backed by abundant data from plant chemical ecology. Sufficient data are also available to conclude that plant defenses act as deterrent and repellent to attacking herbivores, particularly deleterious generalist insects. In the wild, generalist species are usually not endemic, meaning they are not restricted to certain plant species in a region. Therefore, our objective is to inspect theoretically whether evolution of chemical defenses in all plant species eradicate an endemic by any generalist species. The objective is addressed by developing deterministic ordinary differential equations under the following conditions: Plants without constitutive defenses are susceptible to oviposition by generalist insects, while they become defended against generalists by storing chemical defenses. From the models, we explicitly obtain that a generalist-free stable state is only possible if the vast majority of all plant individuals have chemical defenses. The model also allows one to predict the highest possible percentage of undefended plant individuals, which may be considered as free-riders.

Current status and trends in forest genomics

Forests are not only the most predominant of the Earth's terrestrial ecosystems, but are also the core supply for essential products for human use. However, global climate change and ongoing population explosion severely threatens the health of the forest ecosystem and aggravtes the deforestation and forest degradation. Forest genomics has great potential of increasing forest productivity and adaptation to the changing climate. In the last two decades, the field of forest genomics has advanced quickly owing to the advent of multiple high-throughput sequencing technologies, single cell RNA-seq, clustered regularly interspaced short palindromic repeats (CRISPR)-mediated genome editing, and spatial transcriptomes, as well as bioinformatics analysis technologies, which have led to the generation of multidimensional, multilayered, and spatiotemporal gene expression data. These technologies, together with basic technologies routinely used in plant biotechnology, enable us to tackle many important or unique issues in forest biology, and provide a panoramic view and an integrative elucidation of molecular regulatory mechanisms underlying phenotypic changes and variations. In this review, we recapitulated the advancement and current status of 12 research branches of forest genomics, and then provided future research directions and focuses for each area. Evidently, a shift from simple biotechnology-based research to advanced and integrative genomics research, and a setup for investigation and interpretation of many spatiotemporal development and differentiation issues in forest genomics have just begun to emerge.

Transcriptional Analyses of Genes Related to Fodder Qualities in Giant Leucaena Under Different Stress Environments

Leucaena leucocephala subsp. glabrata (giant leucaena) is a tree legume, whose foliage is used as a fodder for animals because of its high protein content. In spite of being a highly nutritious fodder, giant leucaena foliage has two undesirable secondary metabolites, mimosine and tannin. The amounts of mimosine and tannin in giant leucaena foliage are known to vary under different environmental conditions. Giant leucaena was grown under different salinity, pH and nitrogen availability conditions. It produced the highest amounts of mimosine at pH 6.0-7.0, whereas, variation in soil pH did not affect tannin concentrations. Salinity stress had negative effects on both mimosine and tannin concentrations, while nitrogen abundance promoted both mimosine and tannin production. Seven genes for mimosine and tannin metabolism were isolated from a transcriptome library of giant leucaena. These were mimosine synthase, mimosinase, chalcone synthase, flavanone 3β-hydroxylase, dihydroflavonol reductase, leucoanthocyanidin reductase, and anthocyanidin reductase. The highest level of mimosine synthase activity was observed in the absence of salt in the soils. Mimosine synthase activities had strong positive correlation with mimosine concentrations in the foliage (R² = 0.78) whereas mimosinase expression did not appear to have a direct relationship with salt concentrations. The expression of mimosine synthase was significantly higher in the leucaena foliage under nitrogen abundant condition than in nitrogen deficiency conditions, while mimosinase expression was significantly higher under nitrogen deficiency condition than in nitrogen abundance conditions. Mimosine concentrations in the foliage were positively correlated with the expression levels of mimosine synthase but not mimosinase. Similarly, the concentrations of tannin were positively correlated with expression levels of dihydroflavonol reductase, leucoanthocyanidin reductase, and anthocyanidin reductase. Understanding of the environmental conditions that promote or inhibit transcription of the genes for mimosine and tannin biosynthesis should help to design environmental conditions that inhibit transcription of these genes, resulting in reduced levels of these compounds in the leucaena foliage.

Heterologous expression and characterization of a thermoalkaliphilic SAM-synthetase from giant leucaena (Leucaena leucocephala subsp glabrata)

The cDNA encoding S-adenosylmethionine (SAM) synthetase was isolated from giant leucaena (Leucaena leucocephala subsp. glabrata) root tissue mRNA. Transcriptome data and 5'-RLM-RACE were used to obtain the transcript sequence and clone into the T₇-expression vector pEt14b. N-terminal Histidine-tagged recombinant protein was expressed highly in Escherichia coli, purified and characterized by activity assays. A straightforward method using isocratic reverse-phase HPLC analysis (mobile phase: 0.02M o-phosphoric acid) of enzyme assays determined optimal enzyme activity at pH 10.0, 55 °C and 200 mM KCl. In addition to thermophilic activity, giant leucaena SAM-synthetase remains highly active in solutions containing up to 4 M KCl and accepts Na⁺ to some extent as a substitute for K⁺, a known required cofactor for SAM-synthetases. The enzyme followed Michaelis-Menten kinetics (K_m = 1.82 mM, K_cat = 1.17 s^-1, V_max 243.9 μM. min^-1) and was not inhibited by spermidine, spermine or nicotianamine. Giant leucaena SAM-synthetase is a highly tolerant enzyme to extreme conditions, suggesting further studies on plant SAM-synthetases.

Methods of Mimosine Extraction from Leucaena leucocephala (Lam.) de Wit Leaves

Mimosine is a nonprotein amino acid biosynthesized from OAS (O-acetylserine) and 3H4P (3-hydroxy-4-pyridone or its tautoisomer 3,4-dihydroxypyridine). This amino acid constitutively occurs in all parts of Leucaena leucocephala (Lam.) de Wit plants and is found at higher concentrations in seeds and leaves. This metabolite has several useful activities, such as antioxidant, allelochemical, insecticidal, antimicrobial, metal chelating, and antitumor. Mimosine is well studied in biomedical research due its ability to inhibit cells in the late G1 phase and to induce cell apoptosis. Two simple methods of mimosine extraction from leucaena leaves, pulverized and whole maceration, are described herein in detail.

Methods for metal chelation in plant homeostasis: Review

Metal uptake, transport and storage in plants depend on specialized ligands with closely related functions. Individual studies differing by species, nutrient availability, tissue type, etc. are not comprehensive enough to understand plant metal homeostasis in its entirety. A thorough review is required that distinguishes the role of ligands directly involved in chelation from the myriad of plant responses to general stress. Distinguishing between the functions of metal chelating compounds is the primary focus of this review; reactive oxygen species mediation and other aspects of metal homeostasis are also discussed. High molecular weight ligands (polysaccharides, phytochelatin, metallothionein), low molecular weight ligands (nicotianamine, histidine, secondary metabolites) and select studies which demonstrate the complex nature of plant metal homeostasis are explored.

Biochemistry of plants N-heterocyclic non-protein amino acids

Plants catalyze the biosynthesis of a large number of non-protein amino acids, which are usually toxic for other organisms. In this review, the chemistry and metabolism of N-heterocyclic non-protein amino acids from plants are described. These N-heterocyclic non-protein amino acids are composed of β-substituted alanines and include mimosine, β-pyrazol-1-yl-L-alanine, willardiine, isowillardiine, and lathyrine. These β-substituted alanines consisted of an N-heterocyclic moiety and an alanyl side chain. This review explains how these individual moieties are derived from their precursors and how they are used as the substrate for biosynthesizing the respective N-heterocyclic non-protein amino acids. In addition, known catabolism and possible role of these non-protein amino acids in the actual host is explained.