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Gibberellins (GA) and paclobutrazol (PBZ) are plant growth regulators. GA promotes plant growth and development while PBZ retards plant growth. Little is known about their effects on chlorophyll synthesis and photosynthesis in young oil palm plantlets. In this study, ten-month old young clonal palms were treated with 0.02 g/palm either gibberellic acid (GA3) or PBZ. The PBZ-treated palms were shorter with compact crown, shorter fronds and leaflets, more fronds and higher Soil Plant Analysis Development (SPAD) units, particularly at time point T1. Thus, PBZ suppressed elongation in leaflets, rachis and trunk but increased fronds production and leaf chlorophyll content. Contrastingly, GA3 promoted oil palm height with significant inter-leaflet elongation and lower frond production. Chlorophyll content was also adversely affected in GA3-treated palms at time point T1. Transcriptome sequencing revealed that differentially expressed genes (DEGs) were enriched for metabolic related activities. These genes were mostly downregulated by GA3 treatment. The GA3 treatment also reduced expression of chlorophyll synthesis genes, DEGs encoding components of the photosystems I (PSI) and II (PSII) supercomplexes, cytochrome b6f, Adenosine tri-phosphate (ATP) synthase and Rubisco as well as their assembly factors, translocons and photoreceptors. Meanwhile, PBZ treatment increased expression of geranylgeranyl diphosphate reductase that may inhibit GA biosynthesis but increase chlorophyll synthesis, which was likely correlated to increased chlorophyll content in the darker green leaves of PBZ-treated palms. [ABSTRACT FROM AUTHOR]

Aims: This study was designed to examine the enzyme activity of selected virulent isolates of Ganoderma boninense against oil palm. In a separate in vitro assessment, the effect of macronutrients on the mycelial growth of four selected Ganoderma spp. was also tested. Methodology and results: The study involved a comparison of ligninolytic enzymes; lignin peroxidase (LiP), manganese peroxidase (MnP) and laccase (Lac) profiling of eight isolates of G. boninense, categorized into three levels of aggressiveness, with two control isolates (G. boninense PER71 and G. tornatum NPG1) using solid-state fermentation (SSF). The Principal Component Analysis (PCA) revealed that the isolates had a significant production of ligninolytic enzymes on day 80. The most aggressive isolate, ET61 had the highest Lac production. As for the macronutrient test, mycelial growth for all the Ganoderma spp. was highly affected by potassium (K). Conclusion, significance and impact of study: The findings of this study elucidated the characteristics of G. boninense in relation to enzyme production for the degradation of oil palm lignin and the identification of essential nutrients involved in the survival and growth of Ganoderma spp. The study provides vital information on the pathogenic characteristics of G. boninense isolates involved in biomass degradation along with the role of nutrient on the growth of Ganoderma spp. that may influence basal stem rot (BSR) management in the field. [ABSTRACT FROM AUTHOR]

Cerato-platanin (CP) proteins are small extracellular proteins that play essential roles in the plant-pathogen interactions of some economically important filamentous fungi. At present, there is a lack of information about the roles of CP proteins secreted by Ganoderma boninense , the causal agent of basal stem rot disease in African oil palm, during the early host-pathogen interaction. This work studies the properties and roles of two CP proteins from G. boninense strain PER71. Using bioassay-guided fractionation and nano-LC-MS/MS analysis, we identified peptide matches for G. sinense ZZ0214-1 CP-like and other elicitor proteins in the culture filtrate of G. boninense strain PER71. We found that GbCP2 and GbCP6, two out of nine CP gene models identified in the fungal genome of G. boninense strain PER71, exhibited potential effector properties. We further validated their effector properties by isolating and characterising their coding regions. Interestingly, GbCP6 showed a significant expression level at 11 days post inoculation, indicating its significance in fungal pathogenesis. On the other hand, GbCP2 did not show differential expression at any sampling point, suggesting a different function or role in the pathogenicity of G. boninense. This study identifies GbCP6 as a potential biomarker for early detection of basal stem rot disease in oil palm. [Display omitted] • Ganoderma boninense secretes hypersensitive response-inducing elicitor proteins. • Nine cerato-platanin homologs are present in the G. boninense fungal genome. • GbCP2 and GbCP6 are effector proteins with potential implications in pathogenesis. • GbCP6 emerges as a potential early biomarker for basal stem rot disease. [ABSTRACT FROM AUTHOR]

Basal stem rot (BSR) of oil palm is a disastrous disease caused by a white-rot fungus Ganoderma boninense Pat. Non-ribosomal peptides (NRPs) synthesized by non-ribosomal peptide synthetases (NRPSs) are a group of secondary metabolites that act as fungal virulent factors during pathogenesis in the host. In this study, we aimed to isolate NRPS gene of G. boninense strain UPMGB001 and investigate the role of this gene during G. boninense-oil palm interaction. The isolated NRPS DNA fragment of 8322 bp was used to predict the putative peptide sequence of different domains and showed similarity with G. sinense (85%) at conserved motifs of three main NRPS domains. Phylogenetic analysis of NRPS peptide sequences demonstrated that NRPS of G. boninense belongs to the type VI siderophore family. The roots of 6-month-old oil palm seedlings were artificially inoculated for studying NRPS gene expression and disease severity in the greenhouse. The correlation between high disease severity (50%) and high expression (67-fold) of G. boninense NRPS gene at 4 months after inoculation and above indicated that this gene played a significant role in the advancement of BSR disease. Overall, these findings increase our knowledge on the gene structure of NRPS in G. boninense and its involvement in BSR pathogenesis as an effector gene. [ABSTRACT FROM AUTHOR]

The oil palm (Elaeis guineensis) is an important crop in Malaysia but its productivity is hampered by various biotic and abiotic stresses. Recent studies suggest the importance of signalling molecules in plants in coping against stresses, which includes thiamine (vitamin B1). Thiamine is an essential microelement that is synthesized de novo by plants and microorganisms. The active form of thiamine, thiamine pyrophosphate (TPP), plays a prominent role in metabolic activities particularly as an enzymatic cofactor. Recently, thiamine biosynthesis pathways in oil palm have been characterised but the search of novel regulatory element known as riboswitch is yet to be done. Previous studies showed that thiamine biosynthesis pathway is regulated by an RNA element known as riboswitch. Riboswitch binds a small molecule, resulting in a change in production of the proteins encoded by the mRNA. TPP binds specifically to TPP riboswitch to regulate thiamine biosynthesis through a variety of mechanisms found in archaea, bacteria and eukaryotes. This study was carried out to hunt for TPP riboswitch in oil palm thiamine biosynthesis gene. Riboswitch detection software like RiboSW, RibEx, Riboswitch Scanner and Denison Riboswitch Detector were utilised in order to locate putative TPP riboswitch in oil palm ThiC gene sequence that encodes for the first enzyme in the pyrimidine branch of the pathway. The analysis revealed a 192 bp putative TPP riboswitch located at the 3' untranslated region (UTR) of the mRNA. Further comparative gene analysis showed that the 92-nucleotide aptamer region, where the metabolite binds was conserved inter-species. The secondary structure analysis was also carried out using Mfold Web server and it showed a stem-loop structure manifested with stems (P1-P5) with minimum free energy of -12.26 kcal/mol. Besides that, the interaction of riboswitch and its ligand was determined using isothermal titration calorimetry (ITC) and it yielded an exothermic reaction with 1:1 stoichiometry interaction with binding affinities of 0.178 nM, at 30°C. To further evaluate the ability of riboswitch to control the pathway, exogenous thiamine was applied to four months old of oil palm seedlings and sampling of spear leaves tissue was carried out at days 0, 1, 2 and 3 post-treatment for expression analysis of ThiC gene fragment via quantitative polymerase chain reaction (qPCR). Results showed an approximately 5-fold decrease in ThiC gene expression upon application of exogenous thiamine. Quantification of thiamine and its derivatives was carried out via HPLC and the results showed that it was correlated to the down regulation of ThiC gene expression. The application of exogenous thiamine to oil palm affected ThiC gene expression, which supported the prediction of the presence of TPP riboswitch in the gene. Overall, this study provides the first evidence on the presence, binding and the functionality of TPP riboswitch in oil palm. This study is hoped to pave a way for better understanding on the regulation of thiamine biosynthesis pathway in oil palm, which can later be exploited for various purposes especially in manipulation of thiamine biosynthesis pathways in combating stresses in oil palm. [ABSTRACT FROM AUTHOR]

Abiotic stress reduces plant growth and crop productivity. However, the mechanism underlying posttranscriptional regulations of stress response remains elusive. Herein, we report the posttranscriptional mechanism of nucleocytoplasmic RNA transport of stress‐responsive transcripts mediated by EgRBP42, a heterogeneous nuclear ribonucleoprotein‐like RNA‐binding protein from oil palm, which could be necessary for rapid protein translation to confer abiotic stress tolerance in plants. Transgenic Arabidopsis overexpressing EgRBP42 showed early flowering through alteration of gene expression of flowering regulators and exhibited tolerance towards heat, cold, drought, flood, and salinity stresses with enhanced poststress recovery response by increasing the expression of its target stress‐responsive genes. EgRBP42 harbours nucleocytoplasmic shuttling activity mediated by the nuclear localization signal and the M9‐like domain of EgRBP42 and interacts directly with regulators in the nucleus, membrane, and the cytoplasm. EgRBP42 regulates the nucleocytoplasmic RNA transport of target stress‐responsive transcripts through direct binding to their AG‐rich motifs. Additionally, EgRBP42 transcript and protein induction by environmental stimuli are regulated at the transcriptional and posttranscriptional levels. Taken together, the posttranscriptional regulation of RNA transport mediated by EgRBP42 may change the stress‐responsive protein profiles under abiotic stress conditions leading to a better adaptation of plants to environmental changes. This study shows that EgRBP42, an RNA‐binding protein from oil palm, is involved in plant response to abiotic stress. Overexpression of EgRBP42 in Arabidopsis conferred drought, flood, salinity, and cold tolerance with early flowering. EgRBP42 harbours nucleocytoplasmic shuttling activity, and it interacts directly and is colocalized with stress‐responsive mRNAs in response to abiotic stresses, suggesting that EgRBP42 may be involved in intracellular transport of stress‐responsive RNAs in response to abiotic stress. [ABSTRACT FROM AUTHOR]

The somatic embryogenesis receptor kinase (SERK) gene has been extensively studied in many plant species due to its role in conferring embryogenic competence to somatic cells. The oil palm (Elaeis guineensis Jacq.) full-length SERK I (EgSERK I) cDNA was first isolated from cell suspension culture using RACE-PCR. Total length of EgSERK I cDNA was 2378 bp in length with a 5'UTR region (358 bp) longer than 3'UTR region (130 bp) and the ORF was 1890 bp (629aa). The deduced amino acid sequence of EgSERK I contained protein domains commonly present in reported SERK proteins, including the hallmark proline-rich region and C-terminal domains. EgSERK I was most highly expressed in leaf explants and also detected in all tested tissues, including vegetative tissues, reproductive tissues, embryogenic tissues, and non-embryogenic tissues, suggesting that it may have a broad role in plant growth and development. Expression of EgSERK I in leaf explant was upregulated by minimal auxin concentration at the initial 6 h of incubation in callus induction media. EgSERK I mRNA was detected in the adjacent cells of the vascular tissues in the midvein region of leaf explants which serves as the callus initiation point of callogenesis in oil palm. Collectively, our findings suggest that the EgSERK I gene is involved in the callus initiation stage of oil palm somatic embryogenesis by transducing the signal to switch on the dedifferentiation process, triggering cellular reprogramming to form callus. [ABSTRACT FROM AUTHOR]

LEAFY (LFY) is an important regulator of plant's reproductive system, regulating the transition from vegetative growth to flowering, and also acts as an upstream regulator of floral homeotic MADS-box genes in Arabidopsis. Owing to its importance in flower development, oil palm LFY transcripts were isolated and the expression pattern was characterised to elucidate the role of LFY in oil palm. In addition, the gene expression pattern was analysed to determine a possible correlation of LFY to a type of floral abnormality in clonal palms termed mantling. In this study, three LFY transcripts were isolated from oil palm inflorescence tissue. The isolated cDNAs, OpLFY1, OpLFY2 and its splice variant, OpLFY2v were predicted to encode proteins each consisting of 430, 451 and 181 amino acids, respectively. OpLFY1 and OpLFY2 share 90% and 94% amino acid sequence identity to two different LFYs from Phoenix dactylifera, respectively. OpLFY1 was localised in all floral organ primordia. Quantitative polymerase chain reaction (qPCR) analysis revealed that OpLFY genes are expressed in shoot apical meristem and inflorescence tissues with the highest expression level. The expression of the OpLFY1 gene was significantly lower in stage 1 of inflorescence development in mantled palms compared with that of normal inflorescences, suggesting possible association of the gene with this somaclonal variation. [ABSTRACT FROM AUTHOR]

The formation of callus and somatic embryos remains one of the major bottlenecks in oil palm tissue culture. Unlike other crops, oil palm tissue culture is a very slow process. In the present study, EgGST (GenBank accession no. AIC33066.1), an oil palm gene coding for a putative glutathione S-transferase protein, has been characterized molecularly. The full length cDNA sequence of EgGST isolated from oil palm cultured leaf explants at the 6th week is 1002 bp in length, with an Open Reading Frame (ORF) of 651 bp. The deduced EgGST encodes a 216-amino-acid protein with a predicted molecular mass of 23.68 kD and a pI value of 6.16. Its protein sequence shares 63% identity with the glutathione s-transferase gstf2 from Oryza sativa Indica Group (GenBank accession no. ABR25713.1) and contains thioredoxin fold and chloride channel domain. Real-time RT-PCR results showed that the EgGST transcript was differentially expressed across a time series of fortnightly-cultured leaf explants and had a higher transcript levels in nodular callus (NC) compared to friable callus (FC) for oil palm ortet of clone 4178. EgGST was also found to be preferentially expressed in all tissue culture derived materials except for oil palm cell suspension culture (CSC), whereas there were almost negligible expressions in all the non-tissue culture derived materials, except for root. Hence, it can be suggested that EgGST transcript may possibly be regulated differently at different stages of tissue culture and various tissues. Interestingly, EgGST also displayed a tissue-specific expression pattern via RNA in situ hybridization. To our knowledge, this is the first reported study on the analysis of the localization of target mRNA transcript of EgGST in different oil palm tissues. We postulated that EgGST might play significant roles at different stages of oil palm callogenesis, and could potentially be a candidate marker for oil palm callogenesis. [ABSTRACT FROM AUTHOR]

Abstract: We have cloned three cDNAs encoding chitinases from oil palm, EgCHI1, EgCHI2, and EgCHI3. The abundance of transcripts encoding all three chitinases was relatively higher in oil palm root tissues treated with either Ganoderma boninense or Trichoderma harzianum singly compared to that of untreated oil palm root tissues at 5 week post inoculation (wpi). The expression of EgCHI1 and EgCHI2 was also up-regulated in oil palm roots treated with a combination of G. boninense and T. harzianum at 2, 5 and 8 wpi. The up-regulation of chitinases understudied was likely a universal response of host plant to fungal attack. [Copyright &y& Elsevier]

Basal stem rot is one of the major diseases of oil palm ( Elaies guineensis Jacq.) caused by pathogenic Ganoderma species. Trichoderma and mycorrhizae were proposed to be able to reduce the disease severity. However, their roles in improving oil palm defence system by possibly inducing defence-related genes in the host are not well characterized. To better understand that, transcript profiles of eleven putative defence-related cDNAs in the roots of oil palm inoculated with Trichoderma harzianum T32 and mycorrhizae at different time points were studied. Transcripts encoding putative Bowman-Birk protease inhibitor (EgBBI2) and defensin (EgDFS) increased more than 2 fold in mycorrhizae-treated roots at 6 weeks post inoculation (wpi) compared to those in controls. Transcripts encoding putative dehydrin (EgDHN), glycine-rich RNA binding protein (EgGRRBP), isoflavone reductase (EgIFR), type 2 ribosome inactivating protein (EgT2RIP), and EgDFS increased in the oil palm roots treated with T. harzianum at 6 and/or 12 wpi compared to those in the controls. Some of these genes were also expressed in oil palm roots treated with Ganoderma boninense . This study provides an insight of some defence-related genes induced by Trichoderma and mycorrhizae, and their roles as potential agents to boost the plant defence system. [ABSTRACT FROM AUTHOR]

Summary Nitric oxide associated 1 (NOA1) protein is implicated in plant disease resistance and nitric oxide (NO) biosynthesis. A full-length cDNA encoding of NOA1 protein from oil palm ( Elaeis guineensis ) was isolated and designated as EgNOA1 . Sequence analysis suggested that EgNOA1 was a circular permutated GTPase with high similarity to the bacterial YqeH protein of the YawG/YlqF family. The gene expression of EgNOA1 and NO production in oil palm root tissues treated with Ganoderma boninense , the causal agent of basal stem rot (BSR) disease were profiled to investigate the involvement of EgNOA1 during fungal infection and association with NO biosynthesis. Real-time PCR (qPCR) analysis revealed that the transcript abundance of EgNOA1 in root tissues was increased by G. boninense treatment. NO burst in Ganoderma -treated root tissue was detected using Griess reagent, in advance of the up-regulation of the EgNOA1 transcript. This indicates that NO production was independent of EgNOA1 . However, the induced expression of EgNOA1 in Ganoderma -treated root tissues implies that it might be involved in plant defense responses against pathogen infection. [ABSTRACT FROM AUTHOR]

• An efficient protocol for protoplasts isolation from in vitro leaf and mesocarp of oil palm has been established. • Enzymes composition effect on the yield and viability of protoplast are significant. • Scraping the waxy layer on oil palm leaf increased the protoplast isolation efficiency. • Vacuum treatment enhanced the penetration of enzymes into tissues. • 10% ficoll in 0.6 M mannitol improved the separation of protoplasts from impurities. The absence of a cell wall on the protoplast contributes to its versatility. Its flexibility for DNA manipulation and the possibility of rapid cell-based assay is desirable in the plant biotechnology field. This study was carried out to improve protoplast isolation from oil palm in vitro leaf and mesocarp tissues. The factors affecting protoplast isolation efficiency were optimized, including the protocols and enzyme composition involved, focusing on the oil palm in vitro leaf first. Incubation of oil palm leaf sample with an enzyme mixture of cellulase R-10, macerozyme R-10, driselase, and pectolyase Y-23, for 14 h has successfully produced up to 2.5 × 106 protoplasts g-1 fresh weight (FW)-1 with 95% viability. Incubation of oil palm mesocarp tissue with the optimized enzyme mixture for 2 h at static condition has also successfully produced 3.98 × 106 protoplasts g-1 FW-1 with 85% viability. Besides, it was found that increasing the sample's surface area in contact with enzyme solution by slicing the samples into narrow strips and thin layers has improved the penetration of enzymes into the tissues and enhanced the isolation efficiency. In addition, a plasmolysis step before enzymatic treatment has also improved the protoplast viability by minimizing the damage incurred during isolation. The successful isolation of protoplast from oil palm leaf and mesocarp has enabled the study of gene function and the characterization of endogenous tissue-specific promoter being carried out in vivo. [ABSTRACT FROM AUTHOR]

CRISPR/Cas9 is a powerful genome editing tool applicable to diverse plant species. However, the application of CRISPR/Cas9-ribonucleoproteins (RNPs) in oil palm (Elaeis guineensis) has not yet been reported. In this paper, the specificity, efficiency, and sensitivity of CRISPR/Cas9-RNPs in oil palm were evaluated by assessing the effect of different amounts of Cas9 and heat stress using E. guineensis phytoene desaturase (EgPDS) as the target gene. Seven gRNAs were designed and combined with Cas9 protein to form three combinations of RNPs complexes; RNP1/RNP2, RNP3/RNP4, and RNP5/RNP6/RNP7. Assessment of optimal amount of Cas9 and heat stress using RNP5/RNP6/RNP7 demonstrated that 40 µg of Cas9 and heat treatment at 39ºC increased the genome editing efficiency up to 95% in oil palm protoplasts. The use of both optimal conditions produced targeted mutations at frequencies of up to 63.6% in protoplasts transformed with RNP1/RNP2 and RNP3/RNP4 and up to 100% with RNP5/RNP6/RNP7 combinations. Multiple site mutagenesis at two to three target sites with fragment removal up to 179 bp, 69 bp, and 816 bp occurred at high frequencies producing editing efficiency and a Knockout Score (KO) of 100%. Altogether, this study demonstrates a promising, highly efficient, and precise transgene-free CRISPR/Cas9-RNPs genome editing platform in oil palm that also holds enormous potential for application in other transformation-recalcitrant species. [Display omitted] • Successful delivery of multiple ribonucleoproteins into oil palm protoplasts. • Optimum amount of Cas9 increases the CRISPR/Cas9-RNPs gene editing efficiency. • Heat stress produces a high CRISPR/Cas9-RNPs mutation rate in oil palm protoplasts. • CRISPR/Cas9-RNPs system produces 100% mutation frequency in oil palm protoplasts. [ABSTRACT FROM AUTHOR]

• First report on the use of Discosoma red fluorescent protein (DsRED) - as visual reporter marker in oil palm cells. • Seven DsRED gene vectors driven by a different promoter were constructed and available for the scientific community. • The expression of DsRED in oil palm cells exhibited better photostability and brightness compared to GFP. Genetic modification of oil palm is being carried out to explore new avenues for improving and expanding the potential of oil palm. Multiple bottlenecks in delivering the DNA into oil palm cells and generating the transgenic oil palm required us to look into an alternative marker which could help us assess the efficiency of the transformation system, moreover at the early stage considering that oil palm is a slow growing plant. In this study, we have constructed seven transformation vectors carrying a gene encoding DsRED, each driven by a different promoter, i.e. plant constitutive promoter, oil palm constitutive promoter or oil palm tissue-specific promoter. The vectors were transformed into oil palm embryogenic calli via microprojectile bombardment and the red fluorescence signals were observed after 48 h. Based on the observation, the construct driven by the CaMV35S promoter produced the highest number of red fluorescent spots. The oil palm calli bombarded with pUbi-DsRED plasmid suffered the most number of red fluorescent spots losses from day three until day 42, as compared to other constructs. The red fluorescent signals of DsRED produced across all transformed samples appeared to be bright and very distinctive as compared to the background. [ABSTRACT FROM AUTHOR]

Modification of lipid composition in the mesocarp tissue of oil palm involves genetic manipulation of multiple genes. More than one mesocarp-preferential promoter is necessary for the expression of individual transgenes in the same plant to obviate transcriptional gene silencing. This study aimed to identify genes that are preferentially expressed in the mesocarp tissue and characterize selected candidate mesocarp-preferential promoters. Ten transcripts that were preferentially expressed in the mesocarp tissue were identified from the analysis of 82 transcriptome datasets of 12 different oil palm tissues. The expression of two candidate genes, MSP-C1 and MSP-C6 , was verified to be preferentially expressed in the mesocarp tissues and shown to have a low expression level in non-mesocarp tissues by reverse transcription quantitative real-time PCR (RT-qPCR). MSP-C6 promoter fragments of different lengths were transformed into tomato plants for further characterization. Both unripe and ripe fruits of transgenic tomato plants transformed with a construct harboring the MSP-C6-F1 (2014 bp) promoter were shown to have high beta-glucuronidase (GUS) activities. The findings of this study suggest the potential applications of the MSP-C6 promoter as a molecular tool for genetic engineering of novel traits in fruit crops. • Ten mesocarp-preferential transcripts were identified from the analysis of 82 oil palm transcriptome datasets. • Two candidate genes were verified to be preferentially expressed in the oil palm mesocarp tissues. • The MSP-C6-F1 (2014 bp) promoter fragment was shown to be able to drive preferential gene expression in tomato fruits. • Characterization of mesocarp-specific promoters contribute to future genetic manipulation of oil synthesis in oil palm. [ABSTRACT FROM AUTHOR]

Oil palm is subjected to various diseases including Basal Stem Rot (BSR) which is mainly caused by the basidiomycetes fungi, Ganoderma. However, studies on the fungal infection mechanism especially at molecular level and the biological processes involved are still very limited. Fungal cyclophilin (CYP) has been reported to be involved in fungal pathogenicity but involvement of CYP in the pathogenicity of Ganoderma boninense has not been revealed yet. The main objective of this study is to isolate cDNAs encoding CYP and to profile the expression level of these transcripts during infection stages of G. boninense. In this study, five full-length cDNAs encoding CYP were successfully isolated from G. boninense . They were classified as different family members of CYP because significant differences could be observed on their coding, 5′ or 3′ un-translated regions (UTRs). The expression of these five CYP transcripts in different type of G. boninense tissues and the infecting mycelia tissues was studied using real time quantitative PCR (qPCR). Based on the expression results and analysis, the potential functions of these CYP transcripts were predicted to be involved in the development of fruiting body (GbCYP201) and fungal stress response or pathogenicity (GbCYP203 and GbCYP205). [ABSTRACT FROM AUTHOR]

Abstract: Basal stem rot (BSR) is a major disease of oil palm caused by a pathogenic fungus, Ganoderma boninense. However, the interaction between the host plant and its pathogen is not well characterized. To better understand the response of oil palm to G. boninense, transcript profiles of eleven putative defence-related genes from oil palm were measured by quantitative reverse-transcription (qRT)-PCR in the roots of oil palms treated with G. boninense from 3 to 12 weeks post infection (wpi). These transcripts encode putative Bowman–Birk serine protease inhibitors (EgBBI1 and 2), defensin (EgDFS), dehydrin (EgDHN), early methionine-labeled polypeptides (EgEMLP1 and 2), glycine-rich RNA binding protein (EgGRRBP), isoflavone reductase (EgIFR), metallothionein-like protein (EgMT), pathogenesis-related-1 protein (EgPRP), and type 2 ribosome-inactivating protein (EgT2RIP). The transcript abundance of EgBBI2 increased in G. boninense-treated roots at 3 and 6wpi compared to those of controls; while the transcript abundance of EgBBI1, EgDFS, EgEMLP1, EgMT, and EgT2RIP increased in G. boninense-treated roots at 6 or 12wpi. Meanwhile, the gene expression of EgDHN was up-regulated at all three time points in G. boninense-treated roots. The expression profiles of the eleven transcripts were also studied in leaf samples upon inoculation of G. boninense and Trichoderma harzianum to identify potential biomarkers for early detection of BSR. Two candidate genes (EgEMLP1 and EgMT) that have different profiles in G. boninense-treated leaves compared to those infected by T. harzianum may have the potential to be developed as biomarkers for early detection of G. boninense infection. [Copyright &y& Elsevier]

Abstract: Glucanases are enzymes that hydrolyze a variety β-d-glucosidic linkages. Plant β-1,3-glucanases are able to degrade fungal cell walls; and promote the release of cell-wall derived fungal elicitors. In this study, three full-length cDNA sequences encoding oil palm (Elaeis guineensis) glucanases were analyzed. Sequence analyses of the cDNA sequences suggested that EgGlc1-1 is a putative β-d-glucan exohydolase belonging to glycosyl hydrolase (GH) family 3 while EgGlc5-1 and EgGlc5-2 are putative glucan endo-1,3-β-glucosidases belonging to GH family 17. The transcript abundance of these genes in the roots and leaves of oil palm seedlings treated with Ganoderma boninense and Trichoderma harzianum was profiled to investigate the involvement of these glucanases in oil palm during fungal infection. The gene expression of EgGlc1-1 in the root of oil palm seedlings was increased by T. harzianum but suppressed by G. boninense; while the gene expression of both EgGlc5-1 and EgGlc5-2 in the roots of oil palm seedlings was suppressed by G. boninense or/and T. harzianum. [Copyright &y& Elsevier]