The effect of Trichoderma harzianum and T. koningii on the control of tan spot (Pyrenophora tritici-repentis) and leaf blotch (Mycosphaerella graminicola) of wheat under field conditions in Argentina

The effect of six isolates of Trichoderma harzianum and one isolate of T. koningii on the incidence and severity of tan spot (Pyrenophora tritici-repentis) and leaf blotch of wheat (Mycosphaerella graminicola) was evaluated under field conditions. Significant differences between wheat cultivars, inoculum types and growth stages were found. Three of the isolates tested (T2 for M. graminicola, T7 for P. tritici-repentis and T5 for both of them) showed the best performance in controlling leaf blotch and tan spot when coated onto seed or sprayed onto wheat leaves at different growth stages, with significant severity reduction up to 56%. At tillering, six of the isolates reduced the severity of P. tritici-repentis and M. graminicola compared to the control by up to 39% and 12-53%, respectively. In some experiments, the biocontrol preparation (T2 and T5) gave a level of disease control similar to that obtained with Tebuconazole (70 and 48%, respectively). The effect of Trichoderma against P. tritici-repentis was also observed at the heading stage, when six of the treatments reduced disease severity by 16-35%. This is the first report on the efficacy of Trichoderma spp. against wheat necrotrophic pathogens under field conditions in Argentina.     

Synthesis and alpha4beta2 nicotinic affinity of unichiral 5-(2-pyrrolidinyl)oxazolidinones and 2-(2-pyrrolidinyl)benzodioxanes

The RS and SR enantiomers of 2-oxazolidinone and 1,4-benzodioxane bearing a 2-pyrrolidinyl substituent at the 5- and 2-position, respectively, were synthesized as candidate nicotinoids. One of the two benzodioxane stereoisomers reasonably fits the pharmacophore elements of (S)-nicotine and binds at alpha4beta2 nicotinic acetylcholine receptor with submicromolar affinity. Interestingly, both the synthesized pyrrolidinylbenzodioxanes exhibit analogous affinity at alpha(2) adrenergic receptor resembling the behaviour of some known alpha(2)-AR ligands recently proved to possess neuronal nicotinic affinity.     

The identification of genes involved in the stomatal response to reduced atmospheric relative humidity

Stomatal pores of higher plants close in response to decreases in atmospheric relative humidity (RH). This is believed to be a mechanism that prevents the plant from losing excess water when exposed to a dry atmosphere and as such is likely to have been of evolutionary significance during the colonization of terrestrial environments by the embryophytes. We have conducted a genetic screen, based on infrared thermal imaging, to identify Arabidopsis genes involved in the stomatal response to reduced RH. Here we report the characterization of two genes, identified during this screen, which are involved in the guard cell reduced RH signaling pathway. Both genes encode proteins known to be involved in guard cell ABA signaling. OST1 encodes a protein kinase involved in ABA-mediated stomatal closure while ABA2 encodes an enzyme involved in ABA biosynthesis. These results suggest, in contrast to previously published work, that ABA plays a role in the signal transduction pathway connecting decreases in RH to reductions in stomatal aperture. The identification of OST1 as a component required in stomatal RH and ABA signal transduction supports the proposition that guard cell signaling is organized as a network in which some intracellular signaling proteins are shared among different stimuli.     

Discovery of N-[(1-aryl-1H-indazol-5-yl)methyl]amides derivatives as smoothened antagonists for inhibition of the hedgehog pathway

We report the synthesis and biological evaluation of N-[(1-aryl-1H-indazol-5-yl)methyl]amide derivatives as Smoothened antagonists and inhibitors of the Hedgehog pathway. Identification of the lead structure 1 by HTS, followed by SAR study on the amide and aryl portions led to the discovery of antagonists with nanomolar activity.     

New proteins orthologous to cerato-platanin in various <Emphasis Type="Italic">Ceratocystis</Emphasis> species and the purification and characterization of cerato-populin from <Emphasis Type="Italic">Ceratocystis populicola</Emphasis>

Natural variants of cerato-platanin (CP), a pathogen associated molecular pattern (PAMP) protein produced by Ceratocystis platani (the causal agent of the plane canker stain), have been found to be produced by other four species of the genus Ceratocystis, including five clones of Ceratocystis fimbriata isolated from different hosts. All these fungal strains were known to be pathogenic to plants with considerable importance in agriculture, forestry, and as ornamental plants. The putative premature proteins were deduced on the basis of the nucleotide sequence of genes orthologous to the cp gene of C. platani; the deduced premature proteins of Ceratocystis populicola and Ceratocystis variospora reduced the total identity of all the others from 87.3% to 60.3%. Cerato-populin (Pop1), the CP-orthologous protein produced by C. populicola, was purified and characterized. Pop1 was a well-structured α/β protein with a different percentage of the α-helix than CP, and it self-assembled in vitro in ordered aggregates. Moreover, Pop1 behaved as PAMP, since it stimulated poplar leaf tissues to activate defence responses able to reduce consistently the C. populicola growth. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

An ER‐resident membrane protein complex regulates nicotinic acetylcholine receptor subunit composition at the synapse

Nicotinic acetylcholine receptors (nAChRs) are homo‐ or heteropentameric ligand‐gated ion channels mediating excitatory neurotransmission and muscle activation. Regulation of nAChR subunit assembly and transfer of correctly assembled pentamers to the cell surface is only partially understood. Here, we characterize an ER transmembrane (TM) protein complex that influences nAChR cell‐surface expression and functional properties in Caenorhabditis elegans muscle. Loss of either type I TM protein, NRA‐2 or NRA‐4 (n icotinic r eceptor a ssociated), affects two different types of muscle nAChRs and causes in vivo resistance to cholinergic agonists. Sensitivity to subtype‐specific agonists of these nAChRs is altered differently, as demonstrated by whole‐cell voltage‐clamp of dissected adult muscle, when applying exogenous agonists or after photo‐evoked, channelrhodopsin‐2 (ChR2) mediated acetylcholine (ACh) release, as well as in single‐channel recordings in cultured embryonic muscle. These data suggest that nAChRs desensitize faster in nra‐2 mutants. Cell‐surface expression of different subunits of the ‘levamisole‐sensitive’ nAChR (L‐AChR) is differentially affected in the absence of NRA‐2 or NRA‐4, suggesting that they control nAChR subunit composition or allow only certain receptor assemblies to leave the ER.     

Tissue-specific requirements for FGF8 during early inner ear development

Several members of the FGF gene family have been shown to intervene from various tissue sources to direct otic placode induction and otic vesicle formation. In this study we define the roles of FGF8, found in different expression domains during this process, in mice and chickens. By conditional inactivation of Fgf8 in distinct tissue compartments we demonstrate that Fgf8 is required in the mesoderm and endoderm during early inner ear development. In the chicken embryo, overexpression of Fgf8 from various tissue sources during otic specification leads to a loss of otic tissue. In contrast ectopic overexpression of Fgf10, a major player during murine otic induction, does not influence otic vesicle formation in chicken embryos but results in the formation of ectopic structures with a non-otic character. This study underlines the crucial role of a defined Fgf8 expression pattern controlling inner ear formation in vertebrates.