Displaying publications 61 - 80 of 110 in total

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  1. Allele Mining Strategies: Principles and Utilisation for Blast Resistance Genes in Rice (Oryza sativa L.)
    Ashkani S, Yusop MR, Shabanimofrad M, Azady A, Ghasemzadeh A, Azizi P, et al.
    Curr Issues Mol Biol, 2015;17:57-73.
    PMID: 25706446
    Allele mining is a promising way to dissect naturally occurring allelic variants of candidate genes with essential agronomic qualities. With the identification, isolation and characterisation of blast resistance genes in rice, it is now possible to dissect the actual allelic variants of these genes within an array of rice cultivars via allele mining. Multiple alleles from the complex locus serve as a reservoir of variation to generate functional genes. The routine sequence exchange is one of the main mechanisms of R gene evolution and development. Allele mining for resistance genes can be an important method to identify additional resistance alleles and new haplotypes along with the development of allele-specific markers for use in marker-assisted selection. Allele mining can be visualised as a vital link between effective utilisation of genetic and genomic resources in genomics-driven modern plant breeding. This review studies the actual concepts and potential of mining approaches for the discovery of alleles and their utilisation for blast resistance genes in rice. The details provided here will be important to provide the rice breeder with a worthwhile introduction to allele mining and its methodology for breakthrough discovery of fresh alleles hidden in hereditary diversity, which is vital for crop improvement.
    Matched MeSH terms: Plant Diseases/microbiology*
  2. Morphological and molecular characterization of Fusarium. solani and F. oxysporum associated with crown disease of oil palm
    Hafizi R, Salleh B, Latiffah Z
    Braz J Microbiol, 2013;44(3):959-68.
    PMID: 24516465
    Crown disease (CD) is infecting oil palm in the early stages of the crop development. Previous studies showed that Fusarium species were commonly associated with CD. However, the identity of the species has not been resolved. This study was carried out to identify and characterize through morphological approaches and to determine the genetic diversity of the Fusarium species. 51 isolates (39%) of Fusarium solani and 40 isolates (31%) of Fusarium oxysporum were recovered from oil palm with typical CD symptoms collected from nine states in Malaysia, together with samples from Padang and Medan, Indonesia. Based on morphological characteristics, isolates in both Fusarium species were classified into two distinct morphotypes; Morphotypes I and II. Molecular characterization based on IGS-RFLP analysis produced 27 haplotypes among the F. solani isolates and 33 haplotypes for F. oxysporum isolates, which indicated high levels of intraspecific variations. From UPGMA cluster analysis, the isolates in both Fusarium species were divided into two main clusters with the percentage of similarity from 87% to 100% for F. solani, and 89% to 100% for F. oxysporum isolates, which was in accordance with the Morphotypes I and II. The results of the present study indicated that F. solani and F. oxysporum associated with CD of oil palm in Malaysia and Indonesia were highly variable.
    Matched MeSH terms: Plant Diseases/microbiology*
  3. Fulltext Agro-ecological variations of sheath rot disease of rice caused by Sarocladium oryzae and DNA fingerprinting of the pathogen's population structure
    Tajul Islam Chowdhury M, Salim Mian M, Taher Mia MA, Rafii MY, Latif MA
    Genet. Mol. Res., 2015 Dec 28;14(4):18140-52.
    PMID: 26782461 DOI: 10.4238/2015.December.23.1
    To examine the impact of regional and seasonal variations on the incidence and severity of sheath rot, a major seed-borne disease of rice caused by Sarocladium oryzae, data on incidence and severity were collected from 27 selected fields in the Gazipur, Rangpur, Bogra, Chittagong, Comilla, Gopalgonj, Jessore, Manikgonj, and Bhola districts of Bangladesh in rain-fed and irrigated conditions. Cultural variability of 29 pathogen isolates obtained from 8 different locations was studied on potato dextrose agar (PDA) and genetic variability was determined by DNA fingerprinting using variable number tandem repeat-polymerase chain reaction markers. Overall, disease incidence and severity were higher in irrigated rice. Disease incidence and severity were highest in the Bhola district in rain-fed rice and lowest in irrigated rice. Mycelial growth of 29 representative isolates was found to vary on PDA and the isolates were divided into 6 groups. The range of the overall size of conidia of the selected isolates was 2.40-7.20 x 1.20-2.40 μm. Analysis of the DNA fingerprint types of the 29 isolates of S. oryzae, obtained from the amplification reactions, revealed 10 fingerprinting types (FPTs) that were 80% similar. FPT-1 was the largest group and included 13 isolates (44.8%), while FPT-2 was the third largest group and included 3 isolates. Each of FPT-3, 4, 5, and 6 included only 1 isolate. We observed no relationship between cultural and genetic groupings.
    Matched MeSH terms: Plant Diseases/microbiology
  4. Fulltext Population genomics reveals additive and replacing horizontal gene transfers in the emerging pathogen Dickeya solani
    Khayi S, Blin P, Pédron J, Chong TM, Chan KG, Moumni M, et al.
    BMC Genomics, 2015;16:788.
    PMID: 26467299 DOI: 10.1186/s12864-015-1997-z
    Dickeya solani is an emerging pathogen that causes soft rot and blackleg diseases in several crops including Solanum tuberosum, but little is known about its genomic diversity and evolution.
    Matched MeSH terms: Plant Diseases/microbiology
  5. Characterization of the Synergistic Effect of Fungal Isolates in Suppressing Ganoderma boninense and Enhancing Oil Palm Growth
    Anuar MSK, Hashim AM, Sundram S, Rahman SRA, Ho CL, Wong MY, et al.
    J Basic Microbiol, 2025 Jan;65(1):e2400312.
    PMID: 39304989 DOI: 10.1002/jobm.202400312
    The globally vital oil palm, a major oil producer, confronts productivity challenges due to Ganoderma boninense (Gb), causing output decline. Chemical control efforts have proven ineffective, prompting exploration of microbial-based biocontrol. While single fungal biocontrol research exists, the impact of employing multiple biocontrols concurrently to combat Ganoderma and enhance oil palm growth remains uncharted. This study examined four soil-derived fungal isolates for their ability to antagonize Gb PER71 in vitro. Molecular identification categorized them as Talaromyces spp. and Penicillium sp. Moreover, all isolates were revealed to have at least three plant growth-promoting (PGP) traits and were shown to have phosphoric hydrolase, ester hydrolase, peptide hydrolase, and glycosidase activities which are essential for plant growth. Furthermore, the synergistic evaluation of fungal isolates was tested against Gb PER71. One out of six combinations of fungal isolates showed a synergistic effect in vitro, and two showed a synergistic effect in planta. The application of single and combined fungal isolates tested in planta also suppressed Gb PER71 and enhanced oil palm growth compared to control groups. The findings indicate the promising potential of these isolates as biocontrol agents (BCAs) and bioformulations against Gb in oil palm cultivation.
    Matched MeSH terms: Plant Diseases/microbiology
  6. Fulltext Genome-Wide Detection of Genes Under Positive Selection in Worldwide Populations of the Barley Scald Pathogen
    Mohd-Assaad N, McDonald BA, Croll D
    Genome Biol Evol, 2018 Apr 01;10(5):1315-1332.
    PMID: 29722810 DOI: 10.1093/gbe/evy087
    Coevolution between hosts and pathogens generates strong selection pressures to maintain resistance and infectivity, respectively. Genomes of plant pathogens often encode major effect loci for the ability to successfully infect specific host genotypes. Hence, spatial heterogeneity in host genotypes coupled with abiotic factors could lead to locally adapted pathogen populations. However, the genetic basis of local adaptation is poorly understood. Rhynchosporium commune, the pathogen causing barley scald disease, interacts at least partially in a gene-for-gene manner with its host. We analyzed global field populations of 125 R. commune isolates to identify candidate genes for local adaptation. Whole genome sequencing data showed that the pathogen is subdivided into three genetic clusters associated with distinct geographic and climatic regions. Using haplotype-based selection scans applied independently to each genetic cluster, we found strong evidence for selective sweeps throughout the genome. Comparisons of loci under selection among clusters revealed little overlap, suggesting that ecological differences associated with each cluster led to variable selection regimes. The strongest signals of selection were found predominantly in the two clusters composed of isolates from Central Europe and Ethiopia. The strongest selective sweep regions encoded protein functions related to biotic and abiotic stress responses. Selective sweep regions were enriched in genes encoding functions in cellular localization, protein transport activity, and DNA damage responses. In contrast to the prevailing view that a small number of gene-for-gene interactions govern plant pathogen evolution, our analyses suggest that the evolutionary trajectory is largely determined by spatially heterogeneous biotic and abiotic selection pressures.
    Matched MeSH terms: Plant Diseases/microbiology
  7. Fulltext Preparation of Chitosan-Hexaconazole Nanoparticles as Fungicide Nanodelivery System for Combating Ganoderma Disease in Oil Palm
    Maluin FN, Hussein MZ, Yusof NA, Fakurazi S, Idris AS, Zainol Hilmi NH, et al.
    Molecules, 2019 Jul 08;24(13).
    PMID: 31288497 DOI: 10.3390/molecules24132498
    Fungicide is used to control fungal disease by destroying and inhibiting the fungus or fungal spores that cause the disease. However, failure to deliver fungicide to the disease region leads to ineffectiveness in the disease control. Hence, in the present study, nanotechnology has enabled the fungicide active agents (hexaconazole) to be encapsulated into chitosan nanoparticles with the aim of developing a fungicide nanodelivery system that can transport them more effectively to the target cells (Ganoderma fungus). A pathogenic fungus, Ganoderma boninense (G. boninense), is destructive to oil palm whereby it can cause significant loss to oil palm plantations located in the Southeast Asian countries, especially Malaysia and Indonesia. In regard to this matter, a series of chitosan nanoparticles loaded with the fungicide, hexaconazole, was prepared using various concentrations of crosslinking agent sodium tripolyphosphate (TPP). The resulting particle size revealed that the increase of the TPP concentration produced smaller particles. In addition, the in vitro fungicide released at pH 5.5 demonstrated that the fungicide from the nanoparticles was released in a sustainable manner with a prolonged release time up to 86 h. On another note, the in vitro antifungal studies established that smaller particle size leads to lower half maximum effective concentration (EC50) value, which indicates higher antifungal activity against G. boninense.
    Matched MeSH terms: Plant Diseases/microbiology*
  8. Fulltext RNA-seq data of Ganoderma boninense at axenic culture condition and under in planta pathogen-oil palm (Elaeis guineensis Jacq.) interaction
    Wong MY, Govender NT, Ong CS
    BMC Res Notes, 2019 Sep 24;12(1):631.
    PMID: 31551084 DOI: 10.1186/s13104-019-4652-y
    OBJECTIVE: Basal stem rot disease causes severe economic losses to oil palm production in South-east Asia and little is known on the pathogenicity of the pathogen, the basidiomyceteous Ganoderma boninense. Our data presented here aims to identify both the house-keeping and pathogenicity genes of G. boninense using Illumina sequencing reads.

    DESCRIPTION: The hemibiotroph G. boninense establishes via root contact during early stage of colonization and subsequently kills the host tissue as the disease progresses. Information on the pathogenicity factors/genes that causes BSR remain poorly understood. In addition, the molecular expressions corresponding to G. boninense growth and pathogenicity are not reported. Here, six transcriptome datasets of G. boninense from two contrasting conditions (three biological replicates per condition) are presented. The first datasets, collected from a 7-day-old axenic condition provide an insight onto genes responsible for sustenance, growth and development of G. boninense while datasets of the infecting G. boninense collected from oil palm-G. boninense pathosystem (in planta condition) at 1 month post-inoculation offer a comprehensive avenue to understand G. boninense pathogenesis and infection especially in regard to molecular mechanisms and pathways. Raw sequences deposited in Sequence Read Archive (SRA) are available at NCBI SRA portal with PRJNA514399, bioproject ID.

    Matched MeSH terms: Plant Diseases/microbiology
  9. Sheath blight of rice: a review and identification of priorities for future research
    Singh P, Mazumdar P, Harikrishna JA, Babu S
    Planta, 2019 Nov;250(5):1387-1407.
    PMID: 31346804 DOI: 10.1007/s00425-019-03246-8
    MAIN CONCLUSION: Rice sheath blight research should prioritise optimising biological control approaches, identification of resistance gene mechanisms and application in genetic improvement and smart farming for early disease detection. Rice sheath blight, caused by Rhizoctonia solani AG1-1A, is one of the most devasting diseases of the crop. To move forward with effective crop protection against sheath blight, it is important to review the published information related to pathogenicity and disease management and to determine areas of research that require deeper study. While progress has been made in the identification of pathogenesis-related genes both in rice and in the pathogen, the mechanisms remain unclear. Research related to disease management practices has addressed the use of agronomic practices, chemical control, biological control and genetic improvement: Optimising nitrogen fertiliser use in conjunction with plant spacing can reduce spread of infection while smart agriculture technologies such as crop monitoring with Unmanned Aerial Systems assist in early detection and management of sheath blight disease. Replacing older fungicides with natural fungicides and use of biological agents can provide effective sheath blight control, also minimising environmental impact. Genetic approaches that show promise for the control of sheath blight include treatment with exogenous dsRNA to silence pathogen gene expression, genome editing to develop rice lines with lower susceptibility to sheath blight and development of transgenic rice lines overexpressing or silencing pathogenesis related genes. The main challenges that were identified for effective crop protection against sheath blight are the adaptive flexibility of the pathogen, lack of resistant rice varieties, abscence of single resistance genes for use in breeding and low access of farmers to awareness programmes for optimal management practices.
    Matched MeSH terms: Plant Diseases/microbiology
  10. Fulltext Phenazine from Pseudomonas aeruginosa UPMP3 induced the host resistance in oil palm (Elaeis guineensis Jacq.)-Ganoderma boninense pathosystem
    Parvin W, Govender N, Othman R, Jaafar H, Rahman M, Wong MY
    Sci Rep, 2020 Sep 24;10(1):15621.
    PMID: 32973199 DOI: 10.1038/s41598-020-72156-7
    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.
    Matched MeSH terms: Plant Diseases/microbiology
  11. Chitosan-Based Agronanofungicides as a Sustainable Alternative in the Basal Stem Rot Disease Management
    Maluin FN, Hussein MZ, Azah Yusof N, Fakurazi S, Idris AS, Zainol Hilmi NH, et al.
    J Agric Food Chem, 2020 Apr 15;68(15):4305-4314.
    PMID: 32227887 DOI: 10.1021/acs.jafc.9b08060
    The rise of environmental and health concerns due to the excessive use of the conventional fungicide urges the search for sustainable alternatives of agronanofungicides where the latter is aimed to enhance plant uptake and minimize the volatilization, leaching, and runoff of fungicides. With this in mind, fungicides of hexaconazole and/or dazomet were encapsulated into chitosan nanoparticles for the formulation of chitosan-based agronanofungicides. In the present study, chitosan nanoparticles (2 nm), chitosan-hexaconazole nanoparticles (18 and 168 nm), chitosan-dazomet nanoparticles (7 and 32 nm), and chitosan-hexaconazole-dazomet nanoparticles (5 and 58 nm) were synthesized and used as potent antifungal agents in combating the basal stem rot (BSR) disease caused by Ganoderma boninense in which they were evaluated via an artificial inoculation of oil palm seedlings with the rubber woodblock, which was fully colonized with the fungal Ganoderma boninense mycelium. The results revealed that chitosan nanoparticles could act as dual modes of action, which are themselves as a biocide or as a nanocarrier for the existing fungicides. In addition, the particle size of the chitosan-based agronanofungicides plays a crucial role in suppressing and controlling the disease. The synergistic effect of the double-fungicide system of 5 nm chitosan-hexaconazole-dazomet nanoparticles can be observed as the system showed the highest disease reduction with 74.5%, compared to the untreated infected seedlings.
    Matched MeSH terms: Plant Diseases/microbiology
  12. Fulltext Application of Ground-Based LiDAR for Analysing Oil Palm Canopy Properties on the Occurrence of Basal Stem Rot (BSR) Disease
    Husin NA, Khairunniza-Bejo S, Abdullah AF, Kassim MSM, Ahmad D, Azmi ANN
    Sci Rep, 2020 04 15;10(1):6464.
    PMID: 32296108 DOI: 10.1038/s41598-020-62275-6
    Ground-based LiDAR also known as Terrestrial Laser Scanning (TLS) technology is an active remote sensing imaging method said to be one of the latest advances and innovations for plant phenotyping. Basal Stem Rot (BSR) is the most destructive disease of oil palm in Malaysia that is caused by white-rot fungus Ganoderma boninense, the symptoms of which include flattening and hanging-down of the canopy, shorter leaves, wilting green fronds and smaller crown size. Therefore, until now there is no critical investigation on the characterisation of canopy architecture related to this disease using TLS method was carried out. This study proposed a novel technique of BSR classification at the oil palm canopy analysis using the point clouds data taken from the TLS. A total of 40 samples of oil palm trees at the age of nine-years-old were selected and 10 trees for each health level were randomly taken from the same plot. The trees were categorised into four health levels - T0, T1, T2 and T3, which represents the healthy, mildly infected, moderately infected and severely infected, respectively. The TLS scanner was mounted at a height of 1 m and each palm was scanned at four scan positions around the tree to get a full 3D image. Five parameters were analysed: S200 (canopy strata at 200 cm from the top), S850 (canopy strata at 850 cm from the top), crown pixel (number of pixels inside the crown), frond angle (degree of angle between fronds) and frond number. The results taken from statistical analysis revealed that frond number was the best single parameter to detect BSR disease as early as T1. In classification models, a linear model with a combination of parameters, ABD - A (frond number), B (frond angle) and D (S200), delivered the highest average accuracy for classification of healthy-unhealthy trees with an accuracy of 86.67 per cent. It also can classify the four severity levels of infection with an accuracy of 80 per cent. This model performed better when compared to the severity classification using frond number. The novelty of this research is therefore on the development of new approach to detect and classify BSR using point clouds data of TLS.
    Matched MeSH terms: Plant Diseases/microbiology*
  13. Transcriptomic analysis of pepper plants provides insights into host responses to Fusarium solani infestation
    Lau ET, Khew CY, Hwang SS
    J Biotechnol, 2020 May 20;314-315:53-62.
    PMID: 32302654 DOI: 10.1016/j.jbiotec.2020.03.014
    Black pepper is an important commodity crop in Malaysia that generates millions of annual revenue for the country. However, black pepper yield is affected by slow decline disease caused by a soil-borne fungus Fusarium solani. RNA sequencing transcriptomics approach has been employed in this study to explore the differential gene expression in susceptible Piper nigrum L. and resistant Piper colubrinum Link. Gene expression comparative analysis of the two pepper species has yielded 2,361 differentially expressed genes (DEGs). Among them, higher expression of 1,426 DEGs was detected in resistant plant. These DEGs practically demonstrated the major branches of plant-pathogen interaction pathway (Path: ko04626). We selected five groups of defence-related DEGs for downstream qRT-PCR analysis. Cf-9, the gene responsible for recognizing fungal avirulence protein activity was found inexpressible in susceptible plant. However, this gene exhibited promising expression in resistant plant. Inactivation of Cf-9 could be the factor that causes susceptible plant fail in recognition of F. solani and subsequently delay activation of adaptive response to fungal invasion. This vital study advance the understanding of pepper plant defence in response to F. solani and aid in identifying potential solution to manage slow decline disease in black pepper cultivation.
    Matched MeSH terms: Plant Diseases/microbiology
  14. Fluorescence-based immunoassay for the detection of Xanthomonas oryzae pv. oryzae in rice leaf
    Awaludin N, Abdullah J, Salam F, Ramachandran K, Yusof NA, Wasoh H
    Anal Biochem, 2020 12 01;610:113876.
    PMID: 32750357 DOI: 10.1016/j.ab.2020.113876
    The identification of rice bacterial leaf blight disease requires a simple, rapid, highly sensitive, and quantitative approach that can be applied as an early detection monitoring tool in rice health. This paper highlights the development of a turn-off fluorescence-based immunoassay for the early detection of Xanthomonas oryzae pv. oryzae (Xoo), a gram-negative bacterium that causes rice bacterial leaf blight disease. Antibodies against Xoo bacterial cells were produced as specific bio-recognition molecules and the conjugation of these antibodies with graphene quantum dots and gold nanoparticles was performed and characterized, respectively. The combination of both these bio-probes as a fluorescent donor and metal quencher led to changes in the fluorescence signal. The immunoreaction between AntiXoo-GQDs, Xoo cells, and AntiXoo-AuNPs in the immuno-aggregation complex led to the energy transfer in the turn-off fluorescence-based quenching system. The change in fluorescence intensity was proportional to the logarithm of Xoo cells in the range of 100-105 CFU mL-1. The limit of detection was achieved at 22 CFU mL-1 and the specificity test against other plant disease pathogens showed high specificity towards Xoo. The detection of Xoo in real plant samples was also performed in this study and demonstrated satisfactory results.
    Matched MeSH terms: Plant Diseases/microbiology
  15. Fulltext Biophysical characterization of antibacterial compounds derived from pathogenic fungi Ganoderma boninense
    Abdullah S, Oh YS, Kwak MK, Chong K
    J Microbiol, 2021 Feb;59(2):164-174.
    PMID: 33355891 DOI: 10.1007/s12275-021-0551-8
    There have been relatively few studies which support a link between Ganoderma boninense, a phytopathogenic fungus that is particularly cytotoxic and pathogenic to plant tissues and roots, and antimicrobial compounds. We previously observed that liquid-liquid extraction (LLE) using chloroformmethanol-water at a ratio (1:1:1) was superior at detecting antibacterial activities and significant quantities of antibacterial compounds. Herein, we demonstrate that antibacterial secondary metabolites are produced from G. boninense mycelia. Antibacterial compounds were monitored in concurrent biochemical and biophysical experiments. The combined methods included high performance thin-layer chromatography (HPTLC), gas chromatography-mass spectrometry (GC-MS), high-performance liquid chromatography (HPLC), fourier transform infrared (FTIR), and nuclear magnetic resonance (NMR) spectroscopy. The antibacterial compounds derived from mycelia with chloroform-methanol extraction through LLE were isolated via a gradient solvent elution system using HPTLC. The antibacterial activity of the isolated compounds was observed to be the most potent against Staphylococcus aureus ATCC 25923 and multidrug-resistant S. aureus NCTC 11939. GC-MS, HPLC, and FTIR analysis confirmed two antibacterial compounds, which were identified as 4,4,14α-trimethylcholestane (m/z = 414.75; lanostane, C30H54) and ergosta-5,7,22-trien-3β-ol (m/z = 396.65; ergosterol, C28H44O). With the aid of spectroscopic evaluations, ganoboninketal (m/z = 498.66, C30H42O6), which belongs to the 3,4-seco-27-norlanostane triterpene family, was additionally characterized by 2D-NMR analysis. Despite the lack of antibacterial potential exhibited by lanostane; both ergosterol and ganoboninketal displayed significant antibacterial activities against bacterial pathogens. Results provide evidence for the existence of bioactive compounds in the mycelia of the relatively unexplored phytopathogenic G. boninense, together with a robust method for estimating the corresponding potent antibacterial secondary metabolites.
    Matched MeSH terms: Plant Diseases/microbiology*
  16. Oil Palm Defensin: A Thermal Stable Peptide that Restricts the Mycelial Growth of Ganoderma boninense
    Tan YC, Ang CL, Wong MY, Ho CL
    Protein Pept Lett, 2016;23(11):994-1002.
    PMID: 27719656
    Plant defensins are plant defence peptides that have many different biological activities, including antifungal, antimicrobial, and insecticidal activities. A cDNA (EgDFS) encoding defensin was isolated from Elaeis guineensis. The open reading frame of EgDFS contained 231 nucleotides encoding a 71-amino acid protein with a predicted molecular weight at 8.69 kDa, and a potential signal peptide. The eight highly conserved cysteine sites in plant defensins were also conserved in EgDFS. The EgDFS sequence lacking 30 amino acid residues at its N-terminus (EgDFSm) was cloned into Escherichia coli BL21 (DE3) pLysS and successfully expressed as a soluble recombinant protein. The recombinant EgDFSm was found to be a thermal stable peptide which demonstrated inhibitory activity against the growth of G. boninense possibly by inhibiting starch assimilation. The role of EgDFSm in oil palm defence system against the infection of pathogen G. boninense was discussed.
    Matched MeSH terms: Plant Diseases/microbiology
  17. Detection of Oil Palm Root Penetration by Agrobacterium-Mediated Transformed Ganoderma boninense, Expressing Green Fluorescent Protein
    Govender N, Wong MY
    Phytopathology, 2017 04;107(4):483-490.
    PMID: 27918241 DOI: 10.1094/PHYTO-02-16-0062-R
    A highly efficient and reproducible Agrobacterium-mediated transformation protocol for Ganoderma boninense was developed to facilitate observation of the early stage infection of basal stem rot (BSR). The method was proven amenable to different explants (basidiospore, protoplast, and mycelium) of G. boninense. The transformation efficiency was highest (62%) under a treatment combination of protoplast explant and Agrobacterium strain LBA4404, with successful expression of an hyg marker gene and gus-gfp fusion gene under the control of heterologous p416 glyceraldehyde 3-phosphate dehydrogenase promoter. Optimal transformation conditions included a 1:100 Agrobacterium/explant ratio, induction of Agrobacterium virulence genes in the presence of 250 μm acetosyringone, co-cultivation at 22°C for 2 days on nitrocellulose membrane overlaid on an induction medium, and regeneration of transformants on potato glucose agar prepared with 0.6 M sucrose and 20 mM phosphate buffer. Evaluated transformants were able to infect root tissues of oil palm plantlets with needle-like microhyphae during the penetration event. The availability of this model pathogen system for BSR may lead to a better understanding of the pathogenicity factors associated with G. boninense penetration into oil palm roots.
    Matched MeSH terms: Plant Diseases/microbiology*
  18. Antagonistic effects of Streptomyces violaceusniger strain G10 on Fusarium oxysporum f.sp. cubense race 4: indirect evidence for the role of antibiosis in the antagonistic process
    Getha K, Vikineswary S
    J Ind Microbiol Biotechnol, 2002 Jun;28(6):303-10.
    PMID: 12032802
    Fusarium oxysporum f.sp. cubense is the causal pathogen of wilt disease of banana. A cost-effective measure of control for this disease is still not available. Streptomyces violaceusniger strain G10 acts as an antifungal agent antagonistic towards many different phytopathogenic fungi, including different pathogenic races of the Fusarium wilt pathogen. In an attempt to understand the mode of action of this antagonist in nature, the interaction between S. violaceusniger strain G10 and F. oxysporum f.sp. cubense was first studied by paired incubation on agar plates. Evidence for the in vitro antibiosis of strain G10 was demonstrated by inhibition zones in the "cross-plug" assay plates. Microscopic observations showed lysis of hyphal ends in the inhibited fungal colonies. Culture of strain G10 in liquid media produces antifungal metabolites, which showed in vitro antagonistic effects against F. oxysporum f.sp. cubense such as swelling, distortion and excessive branching of hyphae, and inhibition of spore germination. An indirect method was used to show that antibiosis is one of the mechanisms of antagonism by which strain G10 acts against F. oxysporun f.sp. cubense in soil. This study suggests the potential of developing strain G10 for the biological control of Fusarium wilt disease of banana.
    Matched MeSH terms: Plant Diseases/microbiology*
  19. Fulltext FAR1 and FAR2 regulate the expression of genes associated with lipid metabolism in the rice blast fungus Magnaporthe oryzae
    bin Yusof MT, Kershaw MJ, Soanes DM, Talbot NJ
    PLoS One, 2014;9(6):e99760.
    PMID: 24949933 DOI: 10.1371/journal.pone.0099760
    The rice blast fungus Magnaporthe oryzae causes plant disease via specialised infection structures called appressoria. These dome-shaped cells are able to generate enormous internal pressure, which enables penetration of rice tissue by invasive hyphae. Previous studies have shown that mobilisation of lipid bodies and subsequent lipid metabolism are essential pre-requisites for successful appressorium-mediated plant infection, which requires autophagic recycling of the contents of germinated spores and germ tubes to the developing appressorium. Here, we set out to identify putative regulators of lipid metabolism in the rice blast fungus. We report the identification of FAR1 and FAR2, which encode highly conserved members of the Zn2-Cys6 family of transcriptional regulators. We generated Δfar1, Δfar2 and Δfar1Δfar2 double mutants in M. oryzae and show that these deletion mutants are deficient in growth on long chain fatty acids. In addition, Δfar2 mutants are also unable to grow on acetate and short chain fatty acids. FAR1 and FAR2 are necessary for differential expression of genes involved in fatty acid β-oxidation, acetyl-CoA translocation, peroxisomal biogenesis, and the glyoxylate cycle in response to the presence of lipids. Furthermore, FAR2 is necessary for expression of genes associated with acetyl-CoA synthesis. Interestingly, Δfar1, Δfar2 and Δfar1Δfar2 mutants show no observable delay or reduction in lipid body mobilisation during plant infection, suggesting that these transcriptional regulators control lipid substrate utilization by the fungus but not the mobilisation of intracellular lipid reserves during infection-related morphogenesis.
    Matched MeSH terms: Plant Diseases/microbiology*
  20. Rapid detection of Ganoderma-infected oil palms by microwave ergosterol extraction with HPLC and TLC
    Muniroh MS, Sariah M, Zainal Abidin MA, Lima N, Paterson RR
    J Microbiol Methods, 2014 May;100:143-7.
    PMID: 24681306 DOI: 10.1016/j.mimet.2014.03.005
    Detection of basal stem rot (BSR) by Ganoderma of oil palms was based on foliar symptoms and production of basidiomata. Enzyme-Linked Immunosorbent Assays-Polyclonal Antibody (ELISA-PAB) and PCR have been proposed as early detection methods for the disease. These techniques are complex, time consuming and have accuracy limitations. An ergosterol method was developed which correlated well with the degree of infection in oil palms, including samples growing in plantations. However, the method was capable of being optimised. This current study was designed to develop a simpler, more rapid and efficient ergosterol method with utility in the field that involved the use of microwave extraction. The optimised procedure involved extracting a small amount of Ganoderma, or Ganoderma-infected oil palm suspended in low volumes of solvent followed by irradiation in a conventional microwave oven at 70°C and medium high power for 30s, resulting in simultaneous extraction and saponification. Ergosterol was detected by thin layer chromatography (TLC) and quantified using high performance liquid chromatography with diode array detection. The TLC method was novel and provided a simple, inexpensive method with utility in the field. The new method was particularly effective at extracting high yields of ergosterol from infected oil palm and enables rapid analysis of field samples on site, allowing infected oil palms to be treated or culled very rapidly. Some limitations of the method are discussed herein. The procedures lend themselves to controlling the disease more effectively and allowing more effective use of land currently employed to grow oil palms, thereby reducing pressure to develop new plantations.
    Matched MeSH terms: Plant Diseases/microbiology*
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