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Summary: Significant progress has been recently made in our understanding of the evolution of jasmonates biosynthesis and signaling. The bioactive jasmonate activating COI1-JAZ co-receptor differs in bryophytes and vascular plants. Dinor-iso-12-oxo-phytodienoic acid (dn-iso-OPDA) is the bioactive hormone in bryophytes and lycophytes. However, further studies showed that the full activation of hormone signaling in Marchantia polymorpha requires additional unidentified hormones. Δ4-dn-OPDAs were previously identified as novel bioactive jasmonates in M. polymorpha. In this paper, we describe the major bioactive isomer of Δ4-dn-OPDAs as Δ4-dn-iso-OPDA through chemical synthesis, receptor binding assay, and biological activity in M. polymorpha. In addition, we disclosed that Δ4-dn-cis-OPDA is a biosynthetic precursor of Δ4-dn-iso-OPDA. We demonstrated that in planta cis-to-iso conversion of Δ4-dn-cis-OPDA occurs in the biosynthesis of Δ4-dn-iso-OPDA, defining a key biosynthetic step in the chemical evolution of hormone structure. We predict that these findings will facilitate further understanding of the molecular evolution of plant hormone signaling.

Chimaphila umbellata has been studied for almost two centuries now, with the first paper exploring the phytochemistry of the plant published in 1860. Almost all contemporary studies focus on the biotechnological advances of C. umbellata including its utilization as a natural alternative in the cosmetic, food, biofuel, and healthcare industry, with a special focus on its therapeutic uses. This literature review critically investigates the significance and applications of secondary metabolites extracted from the plant and presses on the biotechnological approaches to improve its utilization. C. umbellata is home to many industrially and medicinally important phytochemicals, the majority of which belong to phenolics, sterols, and triterpenoids. Other important compounds include 5-hydroxymethylfurfural, isohomoarbutin, and methyl salicylate (the only essential oil of the plant). Chimaphilin is the characteristic phytochemical of the plant. This review focuses on the phytochemistry of C. umbellata and digs into their chemical structures and attributes. It further discusses the challenges of working with C. umbellata including its alarming conservation status, problems with in-vitro cultivation, and research and development issues. This review concludes with recommendations based on biotechnology, bioinformatics, and their crucial interface. [ABSTRACT FROM AUTHOR]

Summary: Interactions between algae and bacteria are ubiquitous and play fundamental roles in nutrient cycling and biomass production. Recent studies have shown that the plant auxin indole acetic acid (IAA) can mediate chemical crosstalk between algae and bacteria, resembling its role in plant-bacterial associations. Here, we report a mechanism for algal extracellular IAA production from L-tryptophan mediated by the enzyme L-amino acid oxidase (LAO1) in the model Chlamydomonas reinhardtii. High levels of IAA inhibit algal cell multiplication and chlorophyll degradation, and these inhibitory effects can be relieved by the presence of the plant-growth-promoting bacterium (PGPB) Methylobacterium aquaticum, whose growth is mutualistically enhanced by the presence of the alga. These findings reveal a complex interplay of microbial auxin production and degradation by algal-bacterial consortia and draws attention to potential ecophysiological roles of terrestrial microalgae and PGPB in association with land plants.

SUMMARY: Floral scent plays a crucial role in the reproductive process of many plants. Humans have been fascinated by floral scents throughout history, and have transported and traded floral scent products for which they have found multiple uses, such as in food additives, hygiene and perfume products, and medicines. Yet the scientific study of how plants synthesize floral scent compounds began later than studies on most other major plant metabolites, and the first report of the characterization of an enzyme responsible for the synthesis of a floral scent compound, namely linalool in Clarkia breweri, a California annual, appeared in 1994. In the almost 30 years since, enzymes and genes involved in the synthesis of hundreds of scent compounds from multiple plant species have been described. This review recapitulates this history and describes the major findings relating to the various aspects of floral scent biosynthesis and emission, including genes and enzymes and their evolution, storage and emission of scent volatiles, and the regulation of the biochemical processes. Significance Statement: This reviews describes our existing knowledge of how flowers produce and emit volatile compounds, and discusses the reasons for why research in this area lagged behind other topics in plant biochemistry. [ABSTRACT FROM AUTHOR]

In a single vascular plant species, the ubiquitin system consists of thousands of different proteins involved in attaching ubiquitin to substrates, recognizing or processing ubiquitinated proteins, or constituting or regulating the 26S proteasome. The ubiquitin system affects plant health, reproduction, and responses to the environment, processes that impact important agronomic traits. Here we summarize three agronomic traits influenced by ubiquitination: induction of flowering, seed size, and pathogen responses. Specifically, we review how the ubiquitin system affects expression of genes or abundance of proteins important for determining when a plant flowers (focusing on FLOWERING LOCUS C, FRIGIDA, and CONSTANS), highlight some recent studies on how seed size is affected by the ubiquitin system, and discuss how the ubiquitin system affects proteins involved in pathogen or effector recognition with details of recent studies on FLAGELLIN SENSING 2 and SUPPRESSOR OF NPR CONSTITUTIVE 1, respectively, as examples. Finally, we discuss the effects of pathogen-derived proteins on plant host ubiquitin system proteins. Further understanding of the molecular basis of the above processes could identify possible genes for modification or selection for crop improvement.

Summary: The transcription factor LEAFY (LFY) plays crucial roles in flower development by activating floral homeotic genes. Activation of LFY targets requires the combined action of LFY and the E3 ubiquitin ligase UFO, although the precise underlying mechanism remains unclear. Here, we show that LFY accumulates in biomolecular condensates within the cytoplasm, while recombinant LFY forms condensates with similar properties in vitro. UFO interacts with LFY within these condensates and marks it for degradation. LFY levels in the nucleus are buffered against changes in total LFY levels induced by proteasome inhibition, UFO overexpression, or mutation of lysine residues in a disordered region of LFY. Perturbation of cytoplasmic LFY condensates by 1,6-hexanediol treatment induces the relocalization of LFY to the nucleus and the subsequent activation of the LFY target AP3 in flowers. Our data suggest that nucleocytoplasmic partitioning, condensation, and ubiquitin-dependent degradation regulate LFY levels in the nucleus to control its activity.

Summary: To improve the treatment of pigmentation disorders, looking for natural and safe inhibitors of melanin synthesis has become an area of research interest. The quinoa husk peptides reportedly elicit various biological activities (e.g., anti-cancer, antioxidant, anti-hypertensive, and so forth), but its effects on melanin inhibition remain unknown. In the current study, we purified quinoa husk peptides with 30 and 80% ethanol using a macroporous adsorption resin (DA201-C). Component screening revealed that the 80%-ethanol fraction (i.e., QHP fraction) contained numerous short peptides (84.41%) and hydrophobic amino acids (45.60%), while eliciting a superior tyrosinase [TYR]-inhibition rate, 2,2-diphenyl-1-picryhydrazil-scavenging rate, reducing activity, and chelating capacity compared to the 30% fraction and was thus applied in subsequent analyses. Differentially expressed genes in the QHP fraction were primarily enriched in the Akt-signaling pathways based on transcriptomics. Thus, we assessed the expression of related proteins and genes in A375 cells and rat skin cells following treatment with QHP.

Pectins are the most complex polysaccharides of the plant cell wall. Based on the number of methylations, acetylations and glycosidic linkages present in their structures, it is estimated that up to 67 transferase activities are involved in pectin biosynthesis. Pectic galactans constitute a major part of pectin in the form of side-chains of rhamnogalacturonan-I. In Arabidopsis, galactan synthase 1 (GALS1) catalyzes the addition of galactose units from UDP-Gal to growing β-1,4-galactan chains. However, the mechanisms for obtaining varying degrees of polymerization remain poorly understood. In this study, we show that AtGALS1 is bifunctional, catalyzing both the transfer of galactose from UDP-α-d-Gal and the transfer of an arabinopyranose from UDP-β-l-Arap to galactan chains. The two substrates share a similar structure, but UDP-α-d-Gal is the preferred substrate, with a 10-fold higher affinity. Transfer of Arap to galactan prevents further addition of galactose residues, resulting in a lower degree of polymerization. We show that this dual activity occurs both in vitro and in vivo. The herein described bifunctionality of AtGALS1 may suggest that plants can produce the incredible structural diversity of polysaccharides without a dedicated glycosyltransferase for each glycosidic linkage.

The tree of heaven, Ailanthus altissima (MILL.) SWINGLE, is a globally invasive plant known to secrete allelopathic metabolites called quassinoids. Quassinoids are highly modified triterpenoids. So far, nothing has been known about the biochemical basis of quassinoid biosynthesis. Here, based on transcriptome and metabolome data of Ailanthus altissima, we present the first three steps of quassinoid biosynthesis, which are catalysed by an oxidosqualene cyclase and two cytochrome P450 monooxygenases, resulting in the formation of the protolimonoid melianol. Strikingly, these steps are identical to the first steps of the biosynthesis of limonoids, structurally different triterpenoids from sister plant families within the same order Sapindales. Our results are therefore not only important to fully understand the biosynthesis of complex triterpenoids in plants, but also confirm the long-standing hypothesis that quassinoids and limonoids share an evolutionary origin. In addition, our transcriptome data for Ailanthus altissima will be beneficial to other researchers investigating the physiology and ecology of this invasive tree. [ABSTRACT FROM AUTHOR]

To cope with relentless environmental pressures, plants produce an arsenal of structurally diverse chemicals, often called specialized metabolites. These lineage-specific compounds are derived from the simple building blocks made by ubiquitous core metabolic pathways. Although the structures of many specialized metabolites are known, the underlying metabolic pathways and the evolutionary events that have shaped the plant chemical diversity landscape are only beginning to be understood. However, with the advent of multi-omics data sets and the relative ease of studying pathways in previously intractable non-model species, plant specialized metabolic pathways are now being systematically identified. These large datasets also provide a foundation for comparative, phylogeny-guided studies of plant metabolism. Comparisons of metabolic traits and features like chemical abundances, enzyme activities, or gene sequences from phylogenetically diverse plants provide insights into how metabolic pathways evolved. This review highlights the power of studying evolution through the lens of comparative biochemistry, particularly how placing metabolism into a phylogenetic context can help a researcher identify the metabolic innovations enabling the evolution of structurally diverse plant metabolites. [ABSTRACT FROM AUTHOR]

Flavodiiron proteins (FLVs) catalyze the reduction of oxygen to water by using electrons from Photosystem I (PSI). In several photosynthetic organisms such as cyanobacteria, green algae, mosses and gymnosperms, FLV-dependent electron flow protects PSI from over-reduction and consequent damage especially under fluctuating light conditions. In this work we investigated biochemical and structural properties of FLVA and FLVB from the model moss Physcomitrium patens. The two proteins, expressed and purified from Escherichia coli, bind both iron and flavin cofactors and show NAD(P)H oxidase activity as well as oxygen reductase capacities. Moreover, the co-expression of both FLVA and FLVB, coupled to a tandem affinity purification procedure with two different affinity tags, enabled the isolation of the stable and catalytically active FLVA/B hetero tetrameric protein complex with cooperative nature. The multimeric organization was shown to be stabilized by inter-subunit disulfide bonds. This investigation provides valuable new information on the biochemical properties of FLVs, with new insights into their in vivo activity., Competing Interests: Conflict of interest The authors declare that they have no conflicts of interest with the contents of this article., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

The rose aphid, Macrosiphum rosae (L.) (Hemiptera: Aphididae), is one of the most important pests on Rosa species, which cause serious damage to plants. Salicylic acid (SA) and Potassium sulfate (PS) have the potential to affect the population of pests on plants. In this study, different concentrations of SA (0.7 and 1.4 mM), PS (11 and 28 mM) and SA (1.4 mM) + PS (28 mM) were used as foliar applications on rose plants to evaluate the life table parameters of M. rosae. The chemical constituents of rose leaves were also assessed using Gas Chromatography--Mass Spectrometry (GC/MS). Results showed that the life table parameters of M. rosae were significantly affected by various treatments. The longevity of the aphid was longest on control and shortest on SA (1.4 mM). M. rosae had the least fecundity on SA (1.4 mM) treatment. The intrinsic rate of natural increase (rm) of M. rosae ranged from 0.202 to 0.298 day-1 on different treatments, which was lowest on SA (1.4 mM) and highest on control. GC/MS analysis showed that Squalene, 2-(1,3-benzothiazol-2-ylsulfanyl)-1-(3,5- dimethylpyrazol-1-yl) ethanone, and 9,12,15-octadecatrienoic acid, as secondary metabolite, were the major compounds in SA (1.4 mM) treatment. The results of this study demonstrated that application of SA (1.4 mM) on rose plants has a good potential for reducing the population of M. rosae and can be used in integrated pest management programs. [ABSTRACT FROM AUTHOR]

Hormonal balance is important for plant metabolism and, consequently, berry development of grapevines (Vitis vinifera L.). Exogenous application of plant growth regulators (PGRs) combined with mineral elements, in satisfactory dosages, can promotes physiologic efficiency. We investigated the effect of foliar application of PGRs alone or combined with mineral elements on 'Crimson Seedless' grapevines. The metabolism and development of the plants were examined. The treatments were applied via foliar spraying consisting in a PGRs mixture [cytokinin (kinetin—Kt), auxin [4-Indole-3-butyric acid (IBA)], and gibberellin (gibberellic acid—GA3)] and a cobalt (Co) and molybdenum (Mo) mixture were studied. The PGRs and nutrients combined acted as protectors against stress, presenting increases in antioxidant enzyme activities but with a low level of lipid peroxidation. We concluded that the mixture of PGR applied alone or combined with mineral elements favoured content of photosynthetic pigments in the grapevines leaves, antioxidant enzyme activity, translocation and accumulation of reserves. [ABSTRACT FROM AUTHOR]

Ribose can be used for energy or as a component of several important biomolecules, but for it to be used in either capacity it must first be phosphorylated by ribokinase (RBSK). RBSK proteins are part of the phosphofructokinase-B (pfkB) family of carbohydrate kinases. Sequence comparisons of pfkB proteins from the model plant Arabidopsis thaliana with the human and Escherichia coli RBSK identified a single candidate RBSK, At1g17160 (AtRBSK). AtRBSK is more similar to predicted RBSKs from other plant species and known mammalian and prokaryotic RBSK than to all other PfkB proteins in Arabidopsis AtRBSK contains a predicted chloroplast transit peptide, and we confirmed plastid localization using AtRBSK fused to YFP. Structure prediction software verified that the AtRBSK sequence mapped onto a known RBSK structure. Kinetic parameters of purified recombinant AtRBSK were determined to be Kmribose = 150 μm ± 17 μm, KmATP = 45 μm ± 5.6 μm, and kcat = 2.0 s-1 Substrate inhibition was observed for AtRBSK (KiATP = 2.44 mm ± 0.36 mm), as has been demonstrated for other RBSK proteins. Ribose accumulated in Arabidopsis plants lacking AtRBSK. Such plants grew normally unless media was supplemented with ribose, which led to chlorosis and growth inhibition. Both chlorosis and ribose accumulation were abolished upon the introduction of a transgene expressing AtRBSK-MYC, demonstrating that the loss of protein is responsible for ribose hypersensitivity. Ribose accumulation in plants lacking AtRBSK was reduced in plants also deficient in the nucleoside ribohydrolase NSH1, linking AtRBSK activity to nucleoside metabolism.

Light harvesting complex stress-related 3 (LHCSR3) is the protein essential for photoprotective excess energy dissipation (non-photochemical quenching, NPQ) in the model green algaChlamydomonas reinhardtii Activation of NPQ requires low pH in the thylakoid lumen, which is induced in excess light conditions and sensed by lumen-exposed acidic residues. In this work we have used site-specific mutagenesisin vivoandin vitrofor identification of the residues in LHCSR3 that are responsible for sensing lumen pH. Lumen-exposed protonatable residues, aspartate and glutamate, were mutated to asparagine and glutamine, respectively. By expression in a mutant lacking all LHCSR isoforms, residues Asp(117), Glu(221), and Glu(224)were shown to be essential for LHCSR3-dependent NPQ induction inC. reinhardtii Analysis of recombinant proteins carrying the same mutations refoldedin vitrowith pigments showed that the capacity of responding to low pH by decreasing the fluorescence lifetime, present in the wild-type protein, was lost. Consistent with a role in pH sensing, the mutations led to a substantial reduction in binding the NPQ inhibitor dicyclohexylcarbodiimide.

SUMMARY: Rhomboid‐like proteins are intramembrane proteases with a variety of regulatory roles in cells. Though many rhomboid‐like proteins are predicted in plants, their detailed molecular mechanisms or cellular functions are not yet known. Of the 13 predicted rhomboids in Arabidopsis thaliana, one, RBL10, affects lipid metabolism in the chloroplast, because in the respective rbl10 mutant the transfer of phosphatidic acid through the inner envelope membrane is disrupted. Here we show that RBL10 is part of a high‐molecular‐weight complex of 250 kDa or greater in size. Nine likely components of this complex are identified by two independent methods and include Acyl Carrier Protein 4 (ACP4) and Carboxyltransferase Interactor1 (CTI1), which have known roles in chloroplast lipid metabolism. The acp4 mutant has decreased C16:3 fatty acid content of monogalactosyldiacylglycerol, similar to the rbl10 mutant, prompting us to offer a mechanistic model of how an interaction between ACP4 and RBL10 might affect chloroplast lipid assembly. We also demonstrate the presence of a seventh transmembrane domain in RBL10, refining the currently accepted topology of this protein. Taken together, the identity of possible RBL10 complex components as well as insights into RBL10 topology and distribution in the membrane provide a stepping‐stone towards a deeper understanding of RBL10 function in Arabidopsis lipid metabolism. Significance Statement: Little is known about the function of plant rhomboid proteases such as RBL10, which is a chloroplast‐located rhomboid protease previously shown to affect the lipid composition of photosynthetic membranes. Here we provide evidence for an RBL10‐containing complex in the chloroplast and identify several protein interactors, including ACP4 and CTI1, which have roles in lipid metabolism. [ABSTRACT FROM AUTHOR]

Significant progress has been recently made in our understanding of the evolution of jasmonates biosynthesis and signaling. The bioactive jasmonate activating COI1-JAZ co-receptor differs in bryophytes and vascular plants. Dinor -iso -12-oxo-phytodienoic acid (dn- iso -OPDA) is the bioactive hormone in bryophytes and lycophytes. However, further studies showed that the full activation of hormone signaling in Marchantia polymorpha requires additional unidentified hormones. Δ 4 -dn-OPDAs were previously identified as novel bioactive jasmonates in M. polymorpha . In this paper, we describe the major bioactive isomer of Δ 4 -dn-OPDAs as Δ 4 -dn- iso -OPDA through chemical synthesis, receptor binding assay, and biological activity in M. polymorpha . In addition, we disclosed that Δ 4 -dn- cis -OPDA is a biosynthetic precursor of Δ 4 -dn- iso -OPDA. We demonstrated that in planta cis -to- iso conversion of Δ 4 -dn- cis -OPDA occurs in the biosynthesis of Δ 4 -dn- iso -OPDA, defining a key biosynthetic step in the chemical evolution of hormone structure. We predict that these findings will facilitate further understanding of the molecular evolution of plant hormone signaling., Competing Interests: The authors declare no competing interests., (© 2024 The Author(s).)

The Green Revolution left millions of the world's smallholder farmers behind. Increasing the role of farmers in agricultural innovation can help them catch up--and will lead to better science in [...]

Haricot bean is primarily grown in Ethiopia for human consumption and export earnings. A market demand for haricot bean, both in the domestic and export market, has triggered the production of haricot bean in selected areas of Ethiopia though its production is constrained by several factors such as poor soil fertility and erratic rainfall. This study was carried out to investigate the combined effect of phosphorus and sulfur fertilizers on yield, yield related traits and protein content of haricot bean (Phaseolus vulgaris) varieties at the research field of Mekoni Agricultural Research Center during 2016/17 cropping season. The experiment was laid out in split plot design where varieties were assigned to the main plots and fertilizer rates to the sub plots in three replications. Three phosphorus (P) rates (10, 20 and 30 kg ha (-1)) were combined with four sulfur (S) rates (15, 30, 45 and 60 kg ha (-1)) and applied in combination to Melka Awash-98 and Nasir varieties. Data on phenological, agronomic and quality traits were collected and determined. Partial budget analysis was carried out to assess the profitability of the applications. P-S fertilizer treatments were significantly affected by varieties. Treatments were significantly affected by varieties and the imposed P and S rates. The interaction effect due to variety by fertilizer the two factors significantly affect days to flowering, plant height, hundred seed weight and protein content. Tallest plants, fewer days to flowering and maturity, many pods/plant, heavier seeds, higher grain yield ha (-1) and better protein content were recorded where the fertilizer application rate was 20 kg ha (-1)P and 30 kg ha (-1) S for both varieties. Grain yield ranged from 1520 to 3000 kg ha (-1) depending on P-S fertilizer rates and varieties. Nasir variety seems to be superior over Melka Awash-98 for most traits except protein content. However, production of Melka Awash-98 under 20 kg ha (-1)P and 15 kg ha (-1) S fertilization tend to be more economical as it resulted in highest net benefit return. Although not profitable, planting Melka Awash-98 using an application rate of 20 kg ha (-1)P and 30 kg ha (-1) S could be suggested for use in the area to ensure earliness and high grain yield. Key words: Haricot bean, fertilizer, phosphorus, sulfur, irrigation, yield, protein, net benefit, INTRODUCTION Ethiopia is known as the homeland for several domesticated crop plants. It is among the top pulse producing countries in the world. Out of total Ethiopian grain production, pulses [...]

Competence in the processing of soybean is constrained by many factors which directly influence the consumption pattern in Nigeria. Youth involvement in soybean processing is a strategy to successfully incorporate soybean utilization in households across South-west Nigeria. The study identified factors that influence competence in soybean processing among secondary school students in Ibadan metropolis of Oyo state. The study is an offshoot of a training activity embarked by Institute of Agricultural Research and Training, (IAR&T) Ibadan to improve the knowledge of soybean processing among secondary students. Thus, study purposively selected three secondary schools adopted by the Institute and all the senior secondary students formed the study population. However, 30% of the senior students were randomly sampled which gave a total of 203 respondents. Independent variables such as personal characteristics of students, knowledge of benefit of soybean and competence in the processing of soybean were collected using validated questionnaire. Competence was measured in a four-point scale of high competence, average competence, low competence and no competence. Data were described using percentage and mean, and were analyzed using Analysis of Variance (ANOVA), Chi square, Pearson Product Moment Correlation (PPMC), and multiple regression analysis. Findings revealed that the mean age of respondents was 15.9 years and majority (57.6%) was female. Highest education attained by mothers (57.1%) was secondary education and majority (62.6%) of mothers was involved in trading. The knowledge of benefit of soybean was high among majority (64.1%) but majority (62.0%) also had low competence in soybean processing. Data analysis revealed a significant relationship (p Key words: Competence, Knowledge, Soybean processing, nutrition, secondary schools students, adopted schools, INTRODUCTION Soybean contains major vitamins and minerals lacking in other legumes and some cereals. It contains 40% high quality protein, 20% edible vegetable oil and a good balance of amino-acid [...]

Biotic and abiotic stresses cause substantial changes in plant biochemistry. These changes are typically revealed by high-performance liquid chromatography (HPLC) and mass spectroscopy-coupled HPLC (HPLC-MS). This information can be used to determine underlying molecular mechanisms of biotic and abiotic stresses in plants. A growing body of evidence suggests that changes in plant biochemistry can be probed by Raman spectroscopy, an emerging analytical technique that is based on inelastic light scattering. Non-invasive and non-destructive detection and identification of these changes allow for the use of Raman spectroscopy for confirmatory diagnostics of plant biotic and abiotic stresses. In this study, we couple HPLC and HPLC-MS findings on biochemical changes caused by Candidatus Liberibacter spp. (Ca. L. asiaticus) in citrus trees to the spectroscopic signatures of plant leaves derived by Raman spectroscopy. Our results show that Ca. L. asiaticus cause an increase in hydroxycinnamates, the precursors of lignins, and flavones, as well as a decrease in the concentration of lutein that are detected by Raman spectroscopy. These findings suggest that Ca. L. asiaticus induce a strong plant defense response that aims to exterminate bacteria present in the plant phloem. This work also suggests that Raman spectroscopy can be used to resolve stress-induced changes in plant biochemistry on the molecular level. [ABSTRACT FROM AUTHOR]

Pesticides may manipulate plant physiology as non-target organisms. In this study, we examined biochemical responses of pistachio plants (Pistacia vera L.) to imidacloprid and phosalone as common pesticides used to control pistachio psyllids. Enzymatic characterization in treated plants with pesticides showed greater specific activities of superoxide dismutase, catalase, ascorbate peroxidase, guaiacol peroxidase, phenylalanine ammonia-lyase, glutathione reductase, and glutathione S-transferase compared with untreated plants during 14 days after treatment. Further experiments displayed elevated levels of total phenols and total proteins coupled with significant increases in proline and total soluble carbohydrate contents in treated plants in comparison to untreated plants. Moreover, pesticide treatment leads to a significant decrease in polyphenol oxidase activity. Nevertheless, no significant changes in contents of hydrogen peroxide, malondialdehyde, total chlorophyll, and electrolyte leakage index were obtained in treated plants. Pesticides' impacts on host plant physiology resulted in similar responses between two pesticides with differences in peak days. Overall, the findings of this study provide an insight into the side effects of phosalone and imidacloprid, chemicals with no specific target site in plants, on the physiology and biochemistry of pistachio plants at recommended rates. [ABSTRACT FROM AUTHOR]

Biotic and abiotic stresses cause substantial changes in plant biochemistry. These changes are typically revealed by high-performance liquid chromatography (HPLC) and mass spectroscopy-coupled HPLC (HPLC-MS). This information can be used to determine underlying molecular mechanisms of biotic and abiotic stresses in plants. A growing body of evidence suggests that changes in plant biochemistry can be probed by Raman spectroscopy, an emerging analytical technique that is based on inelastic light scattering. Non-invasive and non-destructive detection and identification of these changes allow for the use of Raman spectroscopy for confirmatory diagnostics of plant biotic and abiotic stresses. In this study, we couple HPLC and HPLC-MS findings on biochemical changes caused by Candidatus Liberibacter spp. (Ca. L. asiaticus) in citrus trees to the spectroscopic signatures of plant leaves derived by Raman spectroscopy. Our results show that Ca. L. asiaticus cause an increase in hydroxycinnamates, the precursors of lignins, and flavones, as well as a decrease in the concentration of lutein that are detected by Raman spectroscopy. These findings suggest that Ca. L. asiaticus induce a strong plant defense response that aims to exterminate bacteria present in the plant phloem. This work also suggests that Raman spectroscopy can be used to resolve stress-induced changes in plant biochemistry on the molecular level.

CBL1 is an EF hand Ca2+ binding protein from A. thaliana that is involved in the detection of cellular Ca2+ signals and the downstream signal transmission by interaction with the protein kinase CIPK23. So far, the structure and calcium ion binding affinities of CBL1 remain elusive. In this study it was observed that CBL1 tends to form higher oligomeric states due to an intrinsic hydrophobicity and the presence of the detergent BriJ35 was required for the purification of monomeric and functional protein. Functional insights into the in vitro Ca2+ binding capabilities of CBL1 were obtained by isothermal titration calorimetry (ITC) of the wildtype protein as well as single site EF hand mutants. Based on our results, a binding model of CBL1 for Ca2+ in vivo is proposed. Additionally, upon both, ITC measurements and the analysis of an AlphaFold2 model of CBL1, we could gain first insights into the formation of the dimer interface. We could identify an area around EF hand 4 to be relevant for the structural and functional integrity of monomeric CBL1 and likely EF hand 1 to be involved in the dimer interface. • Thermodynamic analysis of Ca2+, Mg2+, and Mn2+ binding to CBL1. • Mutational studies of individual EF hands in CBL1 allows a proposal of stepwise Ca2+ binding. • First insights in the structural basis for CBL1 dimerization. • Model to relate stepwise Ca2+ binding to the molecular function of CBL1. [ABSTRACT FROM AUTHOR]

The monoterpene (+)-3-carene is associated with resistance of Sitka spruce against white pine weevil, a major North American forest insect pest of pine and spruce. High and low levels of (+)-3-carene in, respectively, resistant and susceptible Sitka spruce genotypes are due to variation of (+)-3-carene synthase gene copy number, transcript and protein expression levels, enzyme product profiles, and enzyme catalytic efficiency. A family of multiproduct (+)-3-carene synthase-like genes of Sitka spruce include the three (+)-3-carene synthases, PsTPS-3car1, PsTPS-3car2, PsTPS-3car3, and the (-)-sabinene synthase PsTPS-sab. Of these, PsTPS-3car2 is responsible for the relatively higher levels of (+)-3-carene in weevil-resistant trees. Here, we identified features of the PsTPS-3car1, PsTPS-3car2, PsTPS-3car3, and PsTPS-sab proteins that determine different product profiles. A series of domain swap and site-directed mutations, supported by structural comparisons, identified the amino acid in position 596 as critical for product profiles dominated by (+)-3-carene in PsTPS-3car1, PsTPS-3car2, and PsTPS-3car3, or (-)-sabinene in PsTPS-sab. A leucine in this position promotes formation of (+)-3-carene, whereas phenylalanine promotes (-)-sabinene. Homology modeling predicts that position 596 directs product profiles through differential stabilization of the reaction intermediate. Kinetic analysis revealed position 596 also plays a role in catalytic efficiency. Mutations of position 596 with different side chain properties resulted in a series of enzymes with different product profiles, further highlighting the inherent plasticity and potential for evolution of alternative product profiles of these monoterpene synthases of conifer defense against insects.

In order to study the false positive problem during detecting heme binding protein with horseradish peroxidase (HRP) as secondary antibody, spinach cytochrome b6f complex (Cyt b6f ) and ferredoxin-NADP+ oxidoreductase (FNR) are used as the test material (the former contains the heme binding protein Cyt f, and the latter does not contain heme group). A comparative experiment is designed through the use of the primary antibody of spinach FNR and secondary antibodies labeled with HRP and alkaline phosphatase (ALP). The results indicate that in the HRP-labeled secondary antibody system, Cyt f could be colored even without the incubation by the primary antibody and the secondary antibody, which is a significant false positive. In the ALP-labeled secondary antibody system, the Cyt f doesn't show color, and only the FNR is colored. In western blot experiments, if the protein to be detected is a heme-binding protein or contains a small amount of heme-binding protein, HRP-labeled secondary antibodies should be avoided and ALP-labeled secondary antibodies or other secondary antibodies should be recommended. It is speculated that the heme-binding protein has an HRP-like oxidoreductase activity, namely it can react with the color developing solution, thereby generating a false positive and interfering with the judgment of the experimental results.

Chlamydomonas reinhardtii cells exposed to abiotic stresses (e.g. nitrogen, zinc, or phosphorus deficiency) accumulate triacylglycerols (TAG), which are stored in lipid droplets. Here, we report that iron starvation leads to formation of lipid droplets and accumulation of TAGs. This occurs between 12 and 24 h after the switch to iron-starvation medium. C. reinhardtii cells deprived of iron have more saturated fatty acid (FA), possibly due to the loss of function of FA desaturases, which are iron-requiring enzymes with diiron centers. The abundance of a plastid acyl-ACP desaturase (FAB2) is decreased to the same degree as ferredoxin. Ferredoxin is a substrate of the desaturases and has been previously shown to be a major target of the iron deficiency response. The increase in saturated FA (C16:0 and C18:0) is concomitant with the decrease in unsaturated FA (C16:4, C18:3, or C18:4). This change was gradual for diacylglyceryl-N,N,N-trimethylhomoserine (DGTS) and digalactosyldiacylglycerol (DGDG), whereas the monogalactosyldiacylglycerol (MGDG) FA profile remained stable during the first 12 h, whereas MGDG levels were decreasing over the same period of time. These changes were detectable after only 2 h of iron starvation. On the other hand, DGTS and DGDG contents gradually decreased until a minimum was reached after 24-48 h. RNA-Seq analysis of iron-starved C. reinhardtii cells revealed notable changes in many transcripts coding for enzymes involved in FA metabolism. The mRNA abundances of genes coding for components involved in TAG accumulation (diacylglycerol acyltransferases or major lipid droplet protein) were increased. A more dramatic increase at the transcript level has been observed for many lipases, suggesting that major remodeling of lipid membranes occurs during iron starvation in C. reinhardtii.

SUMMARY: The high rates of photosynthesis and the carbon‐concentrating mechanism (CCM) in C4 plants are initiated by the enzyme phosphoenolpyruvate (PEP) carboxylase (PEPC). The flow of inorganic carbon into the CCM of C4 plants is driven by PEPC's affinity for bicarbonate (KHCO3), which can be rate limiting when atmospheric CO2 availability is restricted due to low stomatal conductance. We hypothesize that natural variation in KHCO3 across C4 plants is driven by specific amino acid substitutions to impact rates of C4 photosynthesis under environments such as drought that restrict stomatal conductance. To test this hypothesis, we measured KHCO3 from 20 C4 grasses to compare kinetic properties with specific amino acid substitutions. There was nearly a twofold range in KHCO3 across these C4 grasses (24.3 ± 1.5 to 46.3 ± 2.4 μm), which significantly impacts modeled rates of C4 photosynthesis. Additionally, molecular engineering of a low‐HCO3− affinity PEPC identified key domains that confer variation in KHCO3. This study advances our understanding of PEPC kinetics and builds the foundation for engineering increased‐HCO3− affinity and C4 photosynthetic efficiency in important C4 crops. Significance Statement: Phosphoenolpyruvate carboxylase (PEPC) is an essential enzyme involved in C4 photosynthesis and our research determined significant variability in the binding affinity for bicarbonate (KHCO3) among 20 PEPC isozymes from C4 grasses. Additionally, we identified the region of the PEPC enzyme that is responsible for this variability in KHCO3, which builds the foundation for engineering a kinetically enhanced PEPC to increase photosynthesis and production in C4 crops to meet the demands of the growing population. [ABSTRACT FROM AUTHOR]

Late embryogenesis abundant (LEA) proteins are produced during seed embryogenesis and in vegetative tissue in response to various abiotic stressors. A correlation has been established between LEA expression and stress tolerance, yet their precise biochemical mechanism remains elusive. LEA proteins are very rich in hydrophilic amino acids, and they have been found to be intrinsically disordered proteins (IDPs) in vitro. Here, we perform biochemical and structural analyses of the four LEA3 proteins from Arabidopsis thaliana (AtLEA3). We show that the LEA3 proteins are disordered in solution but have regions with propensity for order. All LEA3 proteins were effective cryoprotectants of LDH in the freeze/thaw assays, while only one member, AtLEA3‐4, was shown to bind Cu2+ and Fe3+ ions with micromolar affinity. As well, only AtLEA3‐4 showed binding and a gain in α‐helicity in the presence of the membrane mimic dodecylphosphocholine (DPC). We explored this interaction in greater detail using 15N‐heteronuclear single quantum coherence (HSQC) nuclear magnetic resonance, and demonstrate that two sets of conserved motifs present in AtLEA3‐4 are involved in the interaction with the DPC micelles, which themselves gain α‐helical structure. [ABSTRACT FROM AUTHOR]

Our climate is changing due to anthropogenic emissions of greenhouse gases from the production and use of fossil fuels. Present atmospheric levels of CO2 were last seen 3 million years ago, when planetary temperature sustained high Arctic camels. As scientists and educators, we should feel a professional responsibility to discuss major scientific issues like climate change, and its profound consequences for humanity, with students who look up to us for knowledge and leadership, and who will be most affected in the future. We offer simple to complex backgrounds and examples to enable and encourage biochemistry educators to routinely incorporate this most important topic into their classrooms. [ABSTRACT FROM AUTHOR]

Journal of International Affairs (JIA): What do soil regeneration and carbon farming have to do with climate change? Eric Toensmeier (ET): Regenerating soil involves increasing the carbon stored in the [...]

Virtually all marine life depends on the productivity of phytoplankton--microscopic organisms that work tirelessly at the ocean's surface to absorb the carbon dioxide that gets dissolved into the upper ocean [...]