Plant resistance to pathogens is commonly associated with a hypersensitive response (HR), but the degree to which the HR is responsible for incompatibility is subject to debate. Resistance to aphids is likely to share features with resistance to pathogens but is less well understood. Here, we report effective resistance to the pea aphid Acyrthosiphon pisum in Medicago truncatula. Aphids lost weight and died rapidly (within two days) on the resistant genotype Jemalong, which developed necrotic lesions following infestation. Lesions were induced by nonvascular intracellular stylet punctures by aphids, remained localized to the site of stylet entry, stained for the presence of reactive oxygen species, and were similar to the HR induced by the bacterial pathogen Pseudomonas syringae pv. phaseolicola. The implication that aphid-induced lesions confer resistance was tested by quantitative trait loci analysis using recombinant inbred lines derived from a cross between Jemalong and the susceptible genotype DZA315.16. One major locus, RAP1, was identified that was sufficient to confer race-specific resistance against the pea aphid and was mapped to the middle of chromosome 3. Surprisingly, a separate locus, mapping to the top of chromosome 3, governed aphid-induced HR, indicating that the HR-like lesions are not required for RAP1-mediated aphid resistance.

This study was carried out to evaluate the potential of plastic synthesized using bio-based starch. The method began with extraction of starch from chosen tubers with high content of starch; potato and yam. The samples were first grated, grinded and strained to obtain crude starch, which then centrifuged and rinsed to get pure starch. The starch was then reacted with hydrochloric acid to breakdown amylopectin to prevent the starch from becoming plastic-like. Finally, propan-1,2,3-triol was added as a plasticizer to increase the elasticity of the product. The chemical, mechanical, and thermal properties of the products were analyzed using Fourier transform infrared (FTIR), tensile strength tester and Thermogravimetric analysis (TGA). The FTIR spectra of the product displayed the presence of O-H, C-H, C=O and C-O absorption peaks, which indicate the formation of bioplastic has already occured. The tensile strength obtained for potato and yam starch-based bioplastic are 0.6 MPa and 1.9 MPa, respectively. The result gained from TGA showed that 50% weight loss occurred at 250°C for potato and 310°C for yam-based plastic. The highly biodegradability of the plastic was proven using soil burial test, which observed the percentage of soil biodegradation for potato and yam-based bioplastic in 1 week duration is 43% and 26%, respectively. These bio-based plastics have exhibited good thermal and mechanical properties with high biodegradability that makes them a suitable alternative for the existing conventional plastics.

This study was carried out to determine the potential of waste cooking oil (WCO) in preparation of rigid polyurethane (PU) foam. The raw WCO was first filtered and adsorbed by using sugarcane bagasse activated carbon in order to purify the oil. Next, the adsorbed WCO was used to synthesize polyol via transesterification reaction. The WCO-based polyol was then combined with other chemicals at various ratios to form PU rigid foam. The adsorbed WCO showed the decrease in both free fatty acid percentage and viscosity, from 4.3 % to 0.77 % and from 106 mPa.s to 72.5 mPa.s, respectively. No alteration of functional group observed after adsorption as proven by FTIR spectroscopy. The FTIR spectrum of WCO-based polyol showed the formation of OH absorption peak and supported by the increase in hydroxyl value from 0 to 148.79 mgKOH/g after reaction. The formation of urethane linkages (NHCO) backbone in PU foam was confirmed using FTIR. The properties of PU foam are highly dependent on the chemical composition. The density and compressive strength of 60:54:90:40 of glycerol:water:polyol:amine polyurethane foam are 277.7 kg/m3 and 0.10 MPa, respectively. This study showed that WCO exhibit promising potential as raw material for PU formation.

Cyanobacteria are promising chassis strains for the photosynthetic production of platform and specialty chemicals from carbon dioxide. Their efficient light harvesting and metabolic flexibility abilities have allowed a wide range of biomolecules, such as the bioplastic polylactate precursor D-lactate, to be produced, though usually at relatively low yields. In order to increase photosynthetic electron flow towards the production of D-lactate, we have generated several strains of the marine cyanobacterium Synechococcus sp. PCC 7002 (Syn7002) with deletions in genes involved in cyclic or pseudo-cyclic electron flow around photosystem I. Using a variant of the Chlamydomonas reinhardtii D-lactate dehydrogenase (LDH SRT , engineered to efficiently utilize NADPH in vivo), we have shown that deletion of either of the two flavodiiron flv homologs (involved in pseudocyclic electron transport) or the Syn7002 pgr5 homolog (proposed to be a vital part of the cyclic electron transport pathway) is able to increase D-lactate production in Syn7002 strains expressing LDH SRT and the Escherichia coli LldP (lactate permease), especially at low temperature (25°C) and 0.04% (v/v) CO 2 , though at elevated temperatures (38°C) and/or high (1%) CO 2 concentrations, the effect was less obvious. The Dpgr5 background seemed to be particularly beneficial at 25°C and 0.04% (v/v) CO 2 , with a nearly 7-fold increase in D-lactate accumulation in comparison to the wild-type background (≈1000 vs ≈150 mg/L) and decreased side effects in comparison to the flv deletion strains. Overall, our results show that manipulation of photosynthetic electron flow is a viable strategy to increase production of platform chemicals in cyanobacteria under ambient conditions.