Phytohormones in a universe of regulatory metabolites: lessons from jasmonate.

Small-molecule phytohormones exert control over plant growth, development, and stress responses by coordinating the patterns of gene expression within and between cells. Increasing evidence indicates that currently recognized plant hormones are part of a larger group of regulatory metabolites that have acquired signaling properties during the evolution of land plants. This rich assortment of chemical signals reflects the tremendous diversity of plant secondary metabolism, which offers evolutionary solutions to the daunting challenges of sessility and other unique aspects of plant biology.

Iron(II)-Catalyzed Activation of Si-N and Si-O Bonds Using Hydroboranes.

We report the activation and functionalization of Si-N bonds with pinacol borane catalyzed by a three-coordinate iron(II) β-diketiminate complex. The reactions proceed via the mild activation of silazanes to yield useful hydrosilanes and aminoboranes. The reaction is studied by kinetic analysis, along with a detailed investigation of decomposition pathways using catecholborane as an analogue of the pinacol borane used in catalysis.

Positive predictive values and outcomes for uninformative cell-free DNA tests: An Italian multicentric Cytogenetic and cytogenomic Audit of diagnOstic testing (ICARO study).

Objectives: To establish the positive predictive values (PPV) of cfDNA testing based on data from a nationwide survey of independent clinical cytogenetics laboratories.

Methods: Prenatal diagnostic test results obtained by Italian laboratories between 2013 and March 2020 were compiled for women with positive non-invasive prenatal tests (NIPT), without an NIPT result, and cases where there was sex discordancy between the NIPT and ultrasound. PPV and other summary data were reviewed.

Hydrogen/Halogen Exchange of Phosphines for the Rapid Formation of Cyclopolyphosphines.

The hydrogen/halogen exchange of phosphines has been exploited to establish a truly useable substrate scope and straightforward methodology for the formation of cyclopolyphosphines. Starting from a single dichlorophosphine, a sacrificial proton "donor phosphine" makes the rapid, mild synthesis of cyclopolyphosphines possible: reactions are complete within 10 min at room temperature. Novel (aryl)cyclopentaphosphines (ArP) have been formed in good conversion, with the crystal structures presented.

Phosphirenium Ions as Masked Phosphenium Catalysts: Mechanistic Evaluation and Application in Synthesis.

The utilization of phosphirenium ions is presented; optimized and broadened three-membered ring construction is described together with the use of these ions as efficient pre-catalysts for metal-free carbonyl reduction with silanes. Full characterization of the phosphirenium ions is presented, and initial experimental and computational mechanistic studies indicate that these act as a "masked phosphenium" source that is accessed via ring opening. Catalysis proceeds via associative transfer of {PhP} to a carbonyl nucleophile, H-SiR bond addition over the C=O group, and associative displacement of the product by a further equivalent of the carbonyl substrate, which completes the catalytic cycle.

A primary cell wall cellulose-dependent defense mechanism against vascular pathogens revealed by time-resolved dual transcriptomics.

Background: Cell walls (CWs) are protein-rich polysaccharide matrices essential for plant growth and environmental acclimation. The CW constitutes the first physical barrier as well as a primary source of nutrients for microbes interacting with plants, such as the vascular pathogen Fusarium oxysporum (Fo). Fo colonizes roots, advancing through the plant primary CWs towards the vasculature, where it grows causing devastation in many crops.

Jasmonate biosynthesis arising from altered cell walls is prompted by turgor-driven mechanical compression.

Despite the vital roles of jasmonoyl-isoleucine (JA-Ile) in governing plant growth and environmental acclimation, it remains unclear what intracellular processes lead to its induction. Here, we provide compelling genetic evidence that mechanical and osmotic regulation of turgor pressure represents a key elicitor of JA-Ile biosynthesis. After identifying cell wall mutant alleles in () with elevated JA-Ile in seedling roots, we found that ectopic JA-Ile resulted from cell nonautonomous signals deriving from enlarged cortex cells compressing inner tissues and stimulating JA-Ile production.

Amine-Boranes as Transfer Hydrogenation and Hydrogenation Reagents: A Mechanistic Perspective.

Transfer hydrogenation (TH) has historically been dominated by Meerwein-Ponndorf-Verley (MPV) reactions. However, with growing interest in amine-boranes, not least ammonia-borane (H N⋅BH ), as potential hydrogen storage materials, these compounds have also started to emerge as an alternative reagent in TH reactions. In this Review we discuss TH chemistry using H N⋅BH and their analogues (amine-boranes and metal amidoboranes) as sacrificial hydrogen donors.

Inhibition of jasmonate-mediated plant defences by the fungal metabolite higginsianin B.

Infection of Arabidopsis thaliana by the ascomycete fungus Colletotrichum higginsianum is characterized by an early symptomless biotrophic phase followed by a destructive necrotrophic phase. The fungal genome contains 77 secondary metabolism-related biosynthetic gene clusters, whose expression during the infection process is tightly regulated. Deleting CclA, a chromatin regulator involved in the repression of some biosynthetic gene clusters through H3K4 trimethylation, allowed overproduction of three families of terpenoids and isolation of 12 different molecules.

Plant-Insect Bioassay for Testing Arabidopsis Resistance to the Generalist Herbivore Spodoptera littoralis.

Jasmonates are essential engineers of plant defense responses against many pests, including herbivorous insects. Herbivory induces the production of jasmonic acid (JA) and its bioactive conjugate jasmonoyl-L-isoleucine (JA-Ile), which then triggers a large transcriptional reprogramming to promote plant acclimation. The contribution of the JA pathway, including its components and regulators, to defense responses against insect herbivory can be evaluated by conducting bioassays with a wide range of host plants and insect pests.

Interplay between Plant Cell Walls and Jasmonate Production.

Plant cell walls are sophisticated carbohydrate-rich structures representing the immediate contact surface with the extracellular environment, often serving as the first barrier against biotic and abiotic stresses. Notably, a variety of perturbations in plant cell walls result in upregulated jasmonate (JA) production, a phytohormone with essential roles in defense and growth responses. Hence, cell wall-derived signals can initiate intracellular JA-mediated responses and the elucidation of the underlying signaling pathways could provide novel insights into cell wall maintenance and remodeling, as well as advance our understanding on how is JA biosynthesis initiated.

Wound-Induced Shoot-to-Root Relocation of JA-Ile Precursors Coordinates Arabidopsis Growth.

Multicellular organisms rely on the movement of signaling molecules across cells, tissues, and organs to communicate among distal sites. In plants, localized leaf damage activates jasmonic acid (JA)-dependent transcriptional reprogramming in both harmed and unharmed tissues. Although it has been indicated that JA species can translocate from damaged into distal sites, the identity of the mobile compound(s), the tissues through which they translocate, and the effect of their relocation remain unknown.

Regression analysis of properties of [Au(IPr)(CHR)] complexes.

New [Au(IPr)(CHR)] complexes have been synthesised through protonolysis reactions of [Au(IPr)(OH)] with moderately acidic substrates, CHR. An array of spectroscopic (IR and NMR), structural (X-ray), electronic (DFT) and experimental (reactivity) parameters was collected to quantify the variation in stereoelectronic properties of these new and previously reported [Au(IPr)(CHR)] complexes. Variation of the R substituents on the carbanion ligands (CHR) was found to have a crucial impact on parameters characterising the resulting gold complexes.

Chiral Au - and Au -Isothiourea Complexes: Synthesis, Characterization and Application.

During an investigation into the potential union of Lewis basic isothiourea organocatalysis and gold catalysis, the formation of gold-isothiourea complexes was observed. These novel gold complexes were formed in high yield and were found to be air- and moisture stable. A series of neutral and cationic chiral gold(I) and gold(III) complexes bearing enantiopure isothiourea ligands was therefore synthesized and fully characterized.

Agronomic assessment of the wheat semi-dwarfing gene in contrasting nitrogen treatments and water regimes.

() is the main alternative to the GA-insensitive alleles in hot and dry environments where it reduces plant height without yield penalty. The potential of in northern-European wheat breeding remains unclear, since the close linkage with the photoperiod-insensitive allele is unfavourable in the relatively cool summers. In the present study, two near-isogenic lines (NILs) contrasting for the /tall allele from Mara in a UK-adapted and photoperiod-sensitive wheat variety were evaluated in trials with varying nitrogen fertiliser (N) treatments and water regimes across sites in the UK and Spain.

Influence of bulky yet flexible N-heterocyclic carbene ligands in gold catalysis.

Three new Au(I) complexes of the formula [Au(NHC)(NTf2)] (NHC = N-heterocyclic carbene) bearing bulky and flexible ligands have been synthesised. The ligands studied are IPent, IHept and INon which belong to the 'ITent' ('Tent' for 'tentacular') family of NHC derivatives. The effect of these ligands in gold-promoted transformations has been investigated.

Highly Efficient Gold(I)-Catalyzed Regio- and Stereoselective Hydrocarboxylation of Internal Alkynes.

We report the highly efficient gold-catalyzed hydrocarboxylation of internal alkynes that operates under solvent- and silver-free conditions. This new, simple, and eco-friendly protocol allows for the synthesis of a wide variety of functionalized aryl and alkyl enol esters in high yields, with -stereospecificity and good regioselectivities and without the requirement for purification by chromatography. This process represents an expedient, operationally simple method for the synthesis of enol esters.

Multilayered Organization of Jasmonate Signalling in the Regulation of Root Growth.

Physical damage can strongly affect plant growth, reducing the biomass of developing organs situated at a distance from wounds. These effects, previously studied in leaves, require the activation of jasmonate (JA) signalling. Using a novel assay involving repetitive cotyledon wounding in Arabidopsis seedlings, we uncovered a function of JA in suppressing cell division and elongation in roots.

Gold-acetonyl complexes: from side-products to valuable synthons.

A new synthetic strategy was devised leading to the formation of complexes, such as [Au(IPr)(CH2 COCH3)]. The approach capitalizes on the formation of a decomposition product observed in the course of the synthesis of [Au(IPr)(Cl)]. A library of gold acetonyl complexes containing the most common N-heterocyclic carbene (NHC) ligands has been synthesized.

The squeeze cell hypothesis for the activation of jasmonate synthesis in response to wounding.

Jasmonates are lipid mediators that control defence gene expression in response to wounding and other environmental stresses. These small molecules can accumulate at distances up to several cm from sites of damage and this is likely to involve cell-to-cell jasmonate transport.Also, and independently of jasmonate synthesis, transport and perception, different long distance wound signals that stimulate distal jasmonate synthesis are propagated at apparent speeds of several cm min–1 to tissues distal to wounds in a mechanism that involves clade 3 GLUTAMATE RECEPTOR-LIKE (GLR) genes.

Role of NINJA in root jasmonate signaling.

Wound responses in plants have to be coordinated between organs so that locally reduced growth in a wounded tissue is balanced by appropriate growth elsewhere in the body. We used a JASMONATE ZIM DOMAIN 10 (JAZ10) reporter to screen for mutants affected in the organ-specific activation of jasmonate (JA) signaling in Arabidopsis thaliana seedlings. Wounding one cotyledon activated the reporter in both aerial and root tissues, and this was either disrupted or restricted to certain organs in mutant alleles of core components of the JA pathway including COI1, OPR3, and JAR1.

Palladium-catalyzed arylic/allylic aminations: permutable domino sequences for the synthesis of dihydroquinolines from Morita-Baylis-Hillman adducts.

An efficient palladium-catalyzed synthesis of 1,2-dihydroquinolines has been developed via the reaction between anilines and Morita-Baylis-Hillman adducts derived from o-bromobenzaldehyde. This new Pd(0)-catalyzed pseudo-domino type I sequence involves a Buchwald-Hartwig arylic amination and an allylic amination. When starting from an o-bromo allylic alcohol, the chronology is arylic amination/allylic arylation.

Genetic and physiological analysis of Rht8 in bread wheat: an alternative source of semi-dwarfism with a reduced sensitivity to brassinosteroids.

Over the next decade, wheat grain production must increase to meet the demand of a fast growing human population. One strategy to meet this challenge is to raise wheat productivity by optimizing plant stature. The Reduced height 8 (Rht8) semi-dwarfing gene is one of the few, together with the Green Revolution genes, to reduce stature of wheat (Triticum aestivum L.

Multi-centre phase II clinical trial of yttrium-90 resin microspheres alone in unresectable, chemotherapy refractory colorectal liver metastases.

Background: This multi-centre phase II clinical trial is the first prospective evaluation of radioembolisation of patients with colorectal liver metastases (mCRC) who failed previous oxaliplatin- and irinotecan-based systemic chemotherapy regimens.

Methods: Eligible patients had adequate hepatic, haemopoietic and renal function, and an absence of major hepatic vascular anomalies and hepato-pulmonary shunting. Gastroduodenal and right gastric arteries were embolised before hepatic arterial administration of yttrium-90 resin microspheres (median activity, 1.