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The CRISPR/Cas9 genome editing system has been in the spotlight compared to programmable nucleases such as ZFNs and TALENs due to its simplicity, versatility, and high efficiency. CRISPR/Cas9 has revolutionized plant genetic engineering and is broadly used to edit various plants' genomes, including those transformation-recalcitrant species such as oil palm. This review will comprehensively present the CRISPR-Cas9 system's brief history and underlying mechanisms. We then highlighted the establishment of the CRISPR/Cas9 system in plants with an emphasis on the strategies of highly efficient guide RNA design, the establishment of various CRISPR/Cas9 vector systems, approaches of multiplex editing, methods of transformation for stable and transient techniques, available methods for detecting and analyzing mutations, which have been applied and could be adopted for CRISPR/Cas9 genome editing in oil palm. In addition, we also provide insight into the strategy of DNA-free genome editing and its potential application in oil palm. [ABSTRACT FROM AUTHOR]

The antimicrobial activity of green silver nanoparticles (AgNPs) offers a promising approach for combating in vitro pathogen infections in Eucalyptus pellita (E. pellita) plants. This strategy provides an environmentally sustainable method to improve plant health and resistance. The effect of green synthesised AgNPs on the pathogen-infected in vitro regenerated E. pellita plantlets was examined. Firstly, shoots regenerated from cotyledonary leaf explants of E. pellita were examined in vitro through a direct organogenesis technique using murashige and Skoog (MS) medium supplemented with different concentrations (0.4, 1.3, 2.2, 3.1 and 3.9 µM) of 6-benzylaminopurine (BAP). The elongated shoots were rooted in vitro using ½ MS medium supplemented with different concentrations (0.5, 1, 1.5, 2 and 2.5 µM) of indole-3-butyric acid (IBA). The highest shoot formation from cotyledonary leaves was observed in the MS media supplemented with 2.2 µM BAP, followed by 3.1 µM BAP giving a mean of 7.4 and 6 shoots per explant, respectively. The highest root formation was observed in the ½ MS media supplemented with 1.5 µM IBA, yielding an average of 17.47 roots per explant. Secondly, the antibacterial effect of green AgNPs on tissue-cultured plants was examined by inoculating green AgNPs and three bacterial strains (Bacillus sp. strain EU_UPM1, Pantoea dispersa strain EU_UPM3 and Pantoea dispersa strain EU_UPM2). The results showed that green AgNPs controlled bacterial growth at 100 ppm concentration. The focal point of the current research is to use of green synthesised AgNPs as an efficient antibacterial agent that particularly targets in vitro pathogen infections in E. pellita plants. Thus, this study finds that green AgNPs possess potent antibacterial activity and could therefore be developed as a promising antimicrobial agent for the treatment of bacterial infections, including gram-positive and gram-negative bacteria.Key Message: In vitro inoculation of green AgNPs resulted in better development and enhanced morphological characteristics in the horticulturally important E. pellita plantlets. [ABSTRACT FROM AUTHOR]

Some cyanobacteria species have a high capacity for accumulating phycobiliprotein contents in their cells. However, there is a lack of information on screening tropical freshwater cyanobacteria, particularly phycobiliproteins. In addition, it is unclear which characteristics of cyanobacteria (morphological and/or growth) could affect phycobiliprotein contents. This study aimed to screen and characterise Malaysian indigenous freshwater cyanobacteria for the growth, biomass, and pigment contents and determine the major characteristic that contributed to the variation of phycobiliproteins. The surface/volume (S/V) ratio, specific growth rate, biomass productivity, and pigment contents of the isolated cyanobacteria were analysed. Principal component analysis (PCA) and hierarchical cluster analysis (HCA) were applied to distinguish the factor responsible for phycobiliprotein variations in cyanobacteria. For the phycobiliprotein contents, Arthrospira sp., Pseudanabaena sp., and Synechococcus elongatus showed significantly higher (p < 0.05) amounts of cyanobacterial phycocyanin (C-PC), phycoerythrin (C-PE), and allophycocyanin (C-APC), respectively, than other studied cyanobacteria. This study showed no apparent trend of similarity and difference between the unicellular and filamentous cyanobacteria. In addition, carotenoid contents demonstrated a positive correlation with total phycobiliproteins, C-PC and C-APC. Based on the current findings, Arthrospira sp., Pseudanabaena sp. and Synechococcus elongatus might be the promising candidate to be the C-PC, C-PE and C-APC sources, respectively, for commercial production purposes. The selection of optimal cyanobacterial strain is crucial for efficient phycobiliprotein production. This study underlined the potential of freshwater cyanobacteria in producing respective and total phycobiliproteins. Future studies such as the optimization process should be adopted to improve the phycobiliprotein production of these cyanobacteria significantly. [ABSTRACT FROM AUTHOR]

The production of alkaloids in the intact plant is usually low, and some of them are tissue-specific and growth stage–specific. In this study, the total alkaloid content (TAC) in Polyalthia bullata was determined using different extraction solvents, and the extracts were subjected to LC-MS analysis. The manipulation of alkaloid production in P. bullata callus was further carried out by growing the callus on two basal media (Murashige and Skoog (MS) and Woody Plant Medium (WPM)) containing auxins (2,4-dichlorophenoxyacetic acid (2,4-D), α-naphthaleneacetic acid (NAA), 4-amino-3,5,6-trichloropicolinic acid (picloram), 3,6-dichloro-o-anisic acid (dicamba), indole-3-acetic acid (IAA), and indole-3-butyric acid (IBA)), precursors (L-phenylalanine, L-tyrosine, and L-tryptophan), and elicitors (methyl jasmonate (MeJA), salicylic acid (SA), and chitosan). The methanolic extracts exhibited the highest alkaloid content in leaf, stem, and root tissues (4.61 ± 0.04 to 7.71 ± 0.04 mg/g DW), and nine alkaloids were detected in P. bullata. The callus grown on MS + 30 μM 2,4-D exhibited the highest alkaloid accumulation (31.07 ± 0.05 μg/mg DW) after 6 weeks of culture compared to other media: MS media containing auxins, MS media containing auxins and precursors, and MS media containing auxins and elicitors. Therefore, we conclude that the MS + 30 μM 2,4-D is potent in enhancing alkaloid production in P. bullata callus. [ABSTRACT FROM AUTHOR]

Key message: TAAAAT and a novel motif, GCTTCA found in the oil palm stearoyl-ACP desaturase (SAD1) promoter are involved in regulating mesocarp-specific expression.Abstract: Two key fatty acid biosynthetic genes, stearoyl-ACP desaturase (SAD1), and acyl-carrier protein (ACP3) in Elaeis guineensis (oil palm) showed high level of expression during the period of oil synthesis in the mesocarp [12-19 weeks after anthesis (w.a.a.)] and kernel (12-15 w.a.a.). Both genes are expressed in spear leaves at much lower levels and the expression increased by 1.5-fold to 2.5-fold following treatments with ethylene and abscisic acid (ABA). Both SAD1 and ACP3 promoters contain phytohormone-responsive, light-responsive, abiotic factors/wounding-responsive, endosperm specificity and fruit maturation/ripening regulatory motifs. The activities of the full length and six 5′ deletion fragments of the SAD1 promoter were analyzed in transiently transformed oil palm tissues by quantitative β-glucuronidase (GUS) fluorometric assay. The highest SAD1 promoter activity was observed in the mesocarp followed by kernel and the least in the leaves. GUS activity in the D3 deletion construct (− 486 to + 108) was the highest, while the D2 (− 535 to + 108) gave the lowest suggesting the presence of negative cis-acting regulatory element(s) in the deleted − 535 to − 486 (49 bp). It was found that the 49-bp region binds to the nuclear protein extract from mesocarp but not from leaves in electrophoretic mobility shift assay (EMSA). Further fine-tuned analysis of this 49-bp region using truncated DNA led to the identification of GCTTCA as a novel motif in the SAD1 promoter. Interestingly, another known fruit ripening-related motif, LECPLEACS2 (TAAAAT) was found to be required for effective binding of the novel motif to the mesocarp nuclear protein extract. [ABSTRACT FROM AUTHOR]

Key message: The oil palm EgPAL1 gene promoter and its regulatory region were functional as a promoter in the heterologous system of Arabidopsis according to the cis-acting elements present in that region. The promoter was developmentally regulated, vascular tissue specific and responsive to water stress agents. Abstract: Phenylalanine ammonia lyase (PAL, EC 4.3.1.24) is the key enzyme of the phenylpropanoid pathway which plays important roles in plant development and adaptation. To date, there is no report on the study of PAL from oil palm ( Elaeis guineensis), an economically important oil crop. In this study, the 5′ regulatory sequence of a highly divergent oil palm PAL gene ( EgPAL1) was isolated and fused with GUS in Arabidopsis to create two transgenic plants carrying the minimal promoter with (2302 bp) and without its regulatory elements (139 bp). The regulatory sequence contained cis-acting elements known to be important for plant development and stress response including the AC-II element for lignin biosynthesis and several stress responsive elements. The promoter and its regulatory region were fully functional in Arabidopsis. Its activities were characterised by two common fundamental features of PAL which are responsive to plant internal developmental programme and external factors. The promoter was developmentally regulated in certain organs; highly active in young organs but less active or inactive in mature organs. The presence of the AC elements and global activity of the EgPAL1 promoter in all organs resembled the property of lignin-related genes. The existence of the MBS element and enhancement of the promoter activity by PEG reflected the behaviour of drought-responsive genes. Our findings provide a platform for evaluating oil palm gene promoters in the heterologous system of Arabidopsis and give insights into the activities of EgPAL1 promoter in oil palm. [ABSTRACT FROM AUTHOR]

Proteomic analysis was conducted to identify the rice root proteins induced by exogenous proline and their involvement in root growth. Proteins were extracted from the root tissues grown under two conditions, T1 (control) and T2 (10 mM proline), and profiled by two-dimensional polyacrylamide gel electrophoresis. Seventeen of 30 differentially expressed proteins were identified by mass spectrometry. Proline-treated rice roots showed up-regulation and down-regulation of nine and eight proteins, respectively, when compared to those in the control. Among the differentially expressed proteins, the down-regulation of glutathione reductase and peroxidase could be involved in the regulation of cellular hydrogen peroxide and reactive oxygen species levels that modulate the root cell wall structure. Differentially expressed proteins identified as pathogenesis-related proteins might be related to stress adaptive mechanisms in response to exogenous proline treatment. In addition, differentially expressed protein identified as the fructose-bisphosphate aldolases and cytochrome c oxidase might be associated with energy metabolism, which is needed during root developmental process. This is the first attempt to study the changes in rice root proteome treated with proline. The acquired information could open new avenues for further functional studies on the involvement of proline in modulating root development and its relation to stress adaptation of plants. [ABSTRACT FROM AUTHOR]