Various pre-treatment techniques change the physical and chemical structure of the lignocellulosic biomass and improve hydrolysis rates. The effect of ultrasonic pre-treatment on oil palm empty fruit bunch (OPEFB) fibre prior to acid hydrolysis has been evaluated. The main objective of this study was to determine if ultrasonic pre-treatment could function as a pre-treatment method for the acid hydrolysis of OPEFB fibre at a low temperature and pressure. Hydrolysis at a low temperature was studied using 2% sulphuric acid; 1:25 solid liquid ratio and 100 degrees C operating temperature. A maximum xylose yield of 58% was achieved when the OPEFB fibre was ultrasonicated at 90% amplitude for 45min. In the absence of ultrasonic pre-treatment only 22% of xylose was obtained. However, no substantial increase of xylose formation was observed for acid hydrolysis at higher temperatures of 120 and 140 degrees C on ultrasonicated OPEFB fibre. The samples were then analysed using a scanning electron microscope (SEM) to describe the morphological changes of the OPEFB fibre. The SEM observations show interesting morphological changes within the OPEFB fibre for different acid hydrolysis conditions.
Hydrothermal pretreatment of oil palm mesocarp fiber was conducted in tube reactor at treatment severity ranges of log Ro = 3.66-4.83 and partial removal of hemicellulose with migration of lignin was obtained. Concerning maximal recovery of glucose and xylose, 1.5% NaOH was impregnated in the system and subsequent ball milling treatment was employed to improve the conversion yield. The effects of combined hydrothermal and ball milling pretreatments were evaluated by chemical composition changes by using FT-IR, WAXD and morphological alterations by SEM. The successful of pretreatments were assessed by the degree of enzymatic digestibility of treated samples. The highest xylose and glucose yields obtained were 63.2% and 97.3% respectively at cellulase loadings of 10 FPU/g-substrate which is the highest conversion from OPMF ever reported.
Aluminium (Al) phytotoxicity is an important soil constraint that limits crop yield. The objectives of this study were to investigate how growth, physiology, nutrient content and organic acid concentration is affected by Al, and to assess the degree of Al tolerance in different oil palm progeny (OPP). Four OPPs ['A' (Angola dura × Angola dura), 'B' (Nigerian dura × Nigerian dura), 'C' (Deli dura × AVROS pisifera) and 'D' (Deli dura × Dumpy AVROS pisifera)] were grown in different Al concentrations (0, 100 and 200 μm) in aerated Hoagland solution, pH 4.4, for 80 days. We observed a severe reduction (57.5%) in shoot dry weight, and root tips were reduced by 46.5% in 200 μm Al. In 'B' and 'C', the majority of macro- and micronutrients in plants were reduced significantly by 200 μm Al, with Mg being lowered by more than 50% in roots and shoots. The 200 μm Al treatment resulted in a 56.50% reduction in total leaf area, a 20% reduction in net photosynthesis and a 17% reduction in SPAD chlorophyll value in the third leaf. Root tips (0-5 mm) showed a significant increase in oxalic acid content with increasing Al concentration (∼ 5.86-fold); progeny 'A' had the highest concentration of oxalic acid. There was a significant interaction between Al concentration × OPP on total leaf number, root volume, lateral root length, Mg and K in root and shoot tissues, and Ca and N in shoots. The OPPs could be ranked in their tolerance to Al as: 'A' > 'D' > 'B' > 'C'.
The production of lignin from empty fruit bunch (EFB) has been carried out using liquefaction method with 1-butyl-3-methylimidazolium chloride ([BMIM]Cl) ionic liquid (IL), in presence of sulfuric acid (H2SO4) as a catalyst. Response surface methodology (RSM) based on a factorial Central Composite Design (CCD) was employed to identify the optimum condition for lignin yield. The result indicated that the second order model was adequate for all the independent variables on the response with R(2)=0.8609. The optimum temperature, time, ionic liquid to EFB ratio, and catalyst concentration were 150.5 °C, 151 min, 3:1 wt/wt and 4.73 wt%, respectively for lignin yield=26.6%. The presence of lignin liquefied product was confirmed by UV-Vis and FTIR analysis. It was also demonstrated lignin extraction from lignocellulosic using recycled IL gave sufficient performance.
KEY MESSAGE: Potentially embryogenic oil palms can be identified through leaf transcriptomic signatures. Differential expression of genes involved in flowering time, and stress and light responses may associate with somatic embryogenesis potential. Clonal propagation is an attractive approach for the mass propagation of high yielding oil palms. A major issue hampering the effectiveness of oil palm tissue culture is the low somatic embryogenesis rate. Previous studies have identified numerous genes involved in oil palm somatic embryogenesis, but their association with embryogenic potential has not been determined. In this study, differential expression analysis of leaf transcriptomes from embryogenic and non-embryogenic mother palms revealed that transcriptome profiles from non- and poor embryogenic mother palms were more similar than highly embryogenic palms. A total of 171 genes exhibiting differential expression in non- and low embryogenesis groups could also discriminate high from poor embryogenesis groups of another tissue culture agency. Genes related to flowering time or transition such as FTIP, FRIGIDA-LIKE, and NF-YA were up-regulated in embryogenic ortets, suggesting that reproduction timing of the plant may associate with somatic embryogenesis potential. Several light response or photosynthesis-related genes were down-regulated in embryogenic ortets, suggesting a link between photosynthesis activity and embryogenic potential. As expression profiles of the differentially expressed genes are very similar between non- and low embryogenic groups, machine learning approaches with several candidate genes may generate a more sensitive model to better discriminate non-embryogenic from embryogenic ortets.
Although fungicides could be the best solution in combating fungal infections in crops, however, the phytotoxic level of fungicides to the crops should be tested first to ensure that it is safe for the crops. Moreover, nanocarrier systems of fungicides could play a significant role in the advancement of crop protection. For this reason, chitosan was chosen in the present study as a nanocarrier for fungicides of hexaconazole and/or dazomet in the development of a new generation of agronanofungicides with a high antifungal potent agent and no phytotoxic effect. Hence, the encapsulation of fungicides into the non-toxic biopolymer, chitosan was aims to reduce the phytotoxic level of fungicides. In the present study, the in vivo phytotoxicity of chitosan-fungicides nanoparticles on the physiological and vegetative growth of oil palm seedlings was evaluated in comparison to its pure fungicides as well as the conventional fungicides. The results revealed the formation of chitosan-fungicides nanoparticles could reduce the phytotoxic effect on oil palm seedlings compared to their counterparts, pure fungicides. The chitosan-fungicides nanoparticles were seen to greatly reduce the phytotoxic effect compared to the conventional fungicides with the same active ingredient.
Pseudomonas aeruginosa developed its biocontrol agent property through the production of antifungal derivatives, with the phenazine among them. In this study, the applications of crude phenazine synthesized by Pseudomonas aeruginosa UPMP3 and hexaconazole were comparatively evaluated for their effectiveness to suppress basal stem rot infection in artificially G. boninense-challenged oil palm seedlings. A glasshouse experiment under the randomized completely block design was set with the following treatments: non-inoculated seedlings, G. boninense inoculated seedlings, G. boninense inoculated seedlings with 1 mg/ml phenazine application, G. boninense inoculated seedlings with 2 mg/ml phenazine application and G. boninense inoculated seedlings with 0.048 mg/ml hexaconazole application. Seedlings were screened for disease parameters and plant vigour traits (plant height, plant fresh weight, root fresh, and dry weight, stem diameter, and total chlorophyll) at 1-to-4 month post-inoculation (mpi). The application of 2 mg/ml phenazine significantly reduced disease severity (DS) at 44% in comparison to fungicide application (DS = 67%). Plant vigour improved from 1 to 4 mpi and the rate of disease reduction in seedlings with phenazine application (2 mg/ml) was twofold greater than hexaconazole. At 4, 6 and 8 wpi, an up-regulation of chitinase and β-1,3 glucanase genes in seedlings treated with phenazine suggests the involvement of induced resistance in G. boninense-oil palm pathosystem.
The 1,053-bp promoter of the oil palm metallothionein gene (so-called MSP1) and its 5' deletions were fused to the GUS reporter gene, and analysed in transiently transformed oil palm tissues. The full length promoter showed sevenfold higher activity in the mesocarp than in leaves and 1.5-fold more activity than the CaMV35S promoter in the mesocarp. The 1,053-bp region containing the 5' untranslated region (UTR) gave the highest activity in the mesocarp, while the 148-bp region was required for minimal promoter activity. Two positive regulatory regions were identified at nucleotides (nt) -953 to -619 and -420 to -256 regions. Fine-tune deletion of the -619 to -420 nt region led to the identification of a 21-bp negative regulatory sequence in the -598 to -577 nt region, which is involved in mesocarp-specific expression. Gel mobility shift assay revealed a strong interaction of the leaf nuclear extract with the 21-bp region. An AGTTAGG core-sequence within this region was identified as a novel negative regulatory element controlling fruit-specificity of the MSP1 promoter. Abscisic acid (ABA) and copper (Cu(2+)) induced the activity of the promoter and its 5' deletions more effectively than methyl jasmonate (MeJa) and ethylene. In the mesocarp, the full length promoter showed stronger inducibility in response to ABA and Cu(2+) than its 5' deletions, while in leaves, the -420 nt fragment was the most inducible by ABA and Cu(2+). These results suggest that the MSP1 promoter and its regulatory regions are potentially useful for engineering fruit-specific and inducible gene expression in oil palm.
The ubiquitin extension protein (uep1) gene was identified as a constitutively expressed gene in oil palm. We have isolated and characterized the 5' region of the oil palm uep1 gene, which contains an 828 bp sequence upstream of the uep1 translational start site. Construction of a pUEP1 transformation vector, which contains gusA reporter gene under the control of uep1 promoter, was carried out for functional analysis of the promoter through transient expression studies. It was found that the 5' region of uep1 functions as a constitutive promoter in oil palm and could drive GUS expression in all tissues tested, including embryogenic calli, embryoid, immature embryo, young leaflet from mature palm, green leaf, mesocarp and meristematic tissues (shoot tip). This promoter could also be used in dicot systems as it was demonstrated to be capable of driving gusA gene expression in tobacco.
Oil palm suspension cultures were initiated by transferring the gel-like friable embryogenic tissue onto liquid medium supplemented with auxins. In this study, transcripts that were differentially expressed in oil palm suspension cells cultured at different auxin concentrations were examined using suppression subtractive hybridization. Total RNA was first isolated from oil palm suspension cells proliferated in liquid medium with different hormone concentrations for 6 months. Four different hormone combinations: T1 (0.1 mg/l 2,4-D and 1.0 mg/l NAA), T2 (0.4 mg/l 2,4-D and 1.0 mg/l NAA), T3 (1.0 mg/l NAA), and T4 (0.4 mg/l 2,4-D) were used for the treatments. The first and second subtractions were performed using samples T1 and T2 in forward and reverse order. The other two subtractions were forward and reverse subtractions of T3 and T4, respectively. Reverse northern analyses showed that 14.13% of these clones were preferentially expressed in T1, 13.70% in T2, 14.75% in T3, and 15.70% in T4. Among the 294 cDNA clones that were sequenced, 61 contigs (assembled from 165 sequences) and 129 singletons were obtained. Among the 61 contigs, 10 contigs consist of sequences from treatment T1, 8 contigs were from treatment T2, 10 contigs were contains sequences of treatment T3 and 13 contigs contains sequences of treatment T4. Northern analyses of five transcripts that were shown to be differentially expressed in the oil palm suspension cells by reverse northern analysis revealed that transcripts 16A1 (a putative lignostilbene-alpha,beta-dioxygenase, EgLSD) and 16H12 (a putative ethylene responsive 6, EgER6) were differentially expressed in oil palm suspension cells treated with different levels of auxin.