On the influence of Si:Al ratio and hierarchical porosity of FAU zeolites in solid acid catalysed esterification pretreatment of bio-oil

A family of faujasite (FAU) zeolites with different Si:Al ratio, and/or hierarchical porosity introduced via post-synthetic alkaline desilication treatment, have been evaluated as solid acid catalysts for esterification pretreatments of pyrolysis bio-oil components. Acetic acid esterification with aliphatic and aromatic alcohols including methanol, anisyl alcohol, benzyl alcohol, p-cresol and n-butanol was first selected as a model reaction to identify the optimum zeolite properties. Materials were fully characterised using N2 porosimetry, ICP, XRD, XPS, FT-IR, pyridine adsorption, NH3 TPD, In-situ ATR and inverse gas chromatography (IGC). IGC demonstrates that the surface polarity and hence hydrophobicity of FAU decreases with increased Si:Al ratio. Despite possessing a higher acid site loading and acetic acid adsorption capacity, high Al-content FAU possess weaker acidity than more siliceous catalysts. Esterification activity increases with acid strength and decreasing surface polarity following the order FAU30>FAU6>FAU2.6. The introduction of mesoporosity through synthesis of a hierarchical HFAU30 material further enhances esterification activity through improved acid site accessibility and hydrophobicity. Methanol was the most reactive alcohol for esterification, and evaluated with HFAU30 for the pretreatment of a real pyrolysis bio-oil, reducing the acid content by 76% under mild conditions

Natural Variation in Partial Resistance to Pseudomonas syringae Is Controlled by Two Major QTLs in Arabidopsis thaliana

BACKGROUND: Low-level, partial resistance is pre-eminent in natural populations, however, the mechanisms underlying this form of resistance are still poorly understood. METHODOLOGY/PRINCIPAL FINDINGS: In the present study, we used the model pathosystem Pseudomonas syringae pv. tomato DC3000 (Pst) - Arabidopsis thaliana to study the genetic basis of this form of resistance. Phenotypic analysis of a set of Arabidopsis accessions, based on evaluation of in planta pathogen growth revealed extensive quantitative variation for partial resistance to Pst. It allowed choosing a recombinant inbred line (RIL) population derived from a cross between the accessions Bayreuth and Shahdara for quantitative genetic analysis. Experiments performed under two different environmental conditions led to the detection of two major and two minor quantitative trait loci (QTLs) governing partial resistance to Pst and called PRP-Ps1 to PRP-Ps4. The two major QTLs, PRP-Ps1 and PRP-Ps2, were confirmed in near isogenic lines (NILs), following the heterogeneous inbred families (HIFs) strategy. Analysis of marker gene expression using these HIFs indicated a negative correlation between the induced amount of transcripts of SA-dependent genes PR1, ICS and PR5, and the in planta bacterial growth in the HIF segregating at PRP-Ps2 locus, suggesting an implication of PRP-Ps2 in the activation of SA dependent responses. CONCLUSIONS/SIGNIFICANCE: These results show that variation in partial resistance to Pst in Arabidopsis is governed by relatively few loci, and the validation of two major loci opens the way for their fine mapping and their cloning, which will improve our understanding of the molecular mechanisms underlying partial resistance

Functional characterization of a defense-related class-III chitinase promoter from Lupinus albus, active in legume and monocot tissues

A class-III chitinase promoter was isolated from Lupinus albus. The region 5′ to the coding sequence of the IF3 gene was amplified by gene walking and sequenced. The proximal 2.0 kb sequence contains a predicted promoter site, including a TATA box, near the ATG start site. To test for minimal sequences needed for promoter activity, the region was restricted into fragments of 1.81, 1.51 and 1.13 kb and cloned into the pDM327 vector, upstream from the bar-gus fusion gene for Biolistic™ transformation. Transformation of lupin embryos, bean callus tissue, maize embryos and Ornithogalum callus demonstrated promoter activity for all fragments. In silico analysis identified putative cis-acting elements in the 1.81 kb fragment that could be important in controlling gene expression. Fungal elicitor activated-, woundinducible- and ethylene responsive elements were present in the 1.51 kb fragment. Myb elements and CAAT boxes that regulate responses to environmental factors and modulate promoter efficiency were identified in the 1.81 kb fragment. The 1.51 and 1.81 kb fragments were inserted upstream of the gus gene into the pBI121 vector for Agrobacterium tumefaciens transformation of tobacco. Quantitative GUS assays indicated that the promoter fragments are functional in planta and inducible by defense-related signals, wounding, as well as chemical elicitation. All important elements essential for Bion inducibility are present on the shorter (1.51 kb) promoter fragment, but both 5′ distal and proximal cis-elements are required for full functionality. The IF3 promoter is, thus, suitable for use in defense gene constructs prepared for the production of anthracnose resistant lupin.South African Agricultural Research Council (ARC) and the Protein Research Trust (PRT).http://link.springer.com/journal/106582017-12-31hb2016Plant Scienc