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Oil Palm SSR Resource Interface (OPSRI) . Web-based bioinformatic analysis pipeline for ssr mining
By: DR. ROZANA ROSLI
Publisher: JOPR
Date: 28 Jan 2022

Abstract

Co-dominant simple sequence repeat (SSRs) are popular DNA markers, widely applied in oil palm genetic studies, especially in genetic mapping, marker-trait association, diversity analysis and detecting illegitimacy. A repository having detailed information on SSRs and their inheritance profiles in specific breeding lines is lacking in Malaysia. Such a database enables prioritising polymorphic SSRs for screening, identification of which otherwise can be expensive and time consuming. As such, to facilitate and accelerate development of informative SSRs, oil palm SSR resource interface (OPSRI) was established and currently contains information on 1983 markers that were genotyped successfully across several oil palm breeding lines. OPSRI is a well-structured database that can expedite marker development and reduce redundancy in the on-going efforts at developing DNA markers for genetic analysis of oil palm. The system has been integrated with MISA, Primer3, ORF search script and BLAST to enable SSR identification. This study also characterised a large number of expressed sequence tags (EST)-SSRs using an in-silico approach. The information within the OPSRI database can help accelerate research in oil palm as well as in crops such as coconut and date palm which have a high level of synteny and marker-transferability with oil palm.

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Determination of Reliable Reference Genes for Reverse Transcription Quantitative Real-Time PCR From Oil Palm Transcriptomes
By: MS. NADZIRAH BINTI AMIRUDDIN
Publisher: JOPR
Date: 17 Jan 2022

Abstract

A set of reliable reference genes is essential for accurate quantification and interpretation of gene expression data using reverse transcription quantitative real-time polymerase chain reaction (RT-qPCR). In this study, Roche-454 RNA-seq reads from 27 libraries of various oil palm tissues were systematically analysed to identify a set of potential reference genes. Eleven candidate reference genes were identified from the transcriptome data. These genes, together with three oil palm reference genes previously identified for tissue culture samples (PD000380, PD00569, pOP-EA01332) and five classical housekeeping genes [glyceraldehyde-3-phosphate dehydrogenase (GAPDH), NAD5, TUBULIN, UBIQUITIN, ACTIN] were analysed across samples collected from various tissues from mature oil palm (leaf, root, endosperm, mesocarp, female flowers) and stages of tissue culture (non-embryogenic callus, embryogenic callus, polyembryoids, and shoots from polyembryoids). The expression levels of these genes were compared and evaluated using geNorm. Three genes (EgREF_5, EgREF_7 and EgREF_11) were found to be appropriate reference genes for normalising gene expression data from both mature plant and tissue culture samples.

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Detection of ploidy and chromosomal aberrations in commercial oil palm using high-throughput SNP markers
By: MDM. TING NGOOT CHIN
Publisher: Planta
Date: 5 Jan 2021

Abstract

Oil palm produces a quarter of the world.s total vegetable oil. In line with its global importance, an initiative to sequence the oil palm genome was carried out successfully, producing huge amounts of sequence information, allowing SNP discovery. High-capacity SNP genotyping platforms have been widely used for marker.trait association studies in oil palm. Besides genotyping, a SNP array is also an attractive tool for understanding aberrations in chromosome inheritance. Exploiting this, the present study utilized chromosome-wide SNP allelic distributions to determine the ploidy composition of over 1,000 oil palms from a commercial F1 family, including 197 derived from twin-embryo seeds. Our method consisted of an inspection of the allelic intensity ratio using SNP markers. For palms with a shifted or abnormal distribution ratio, the SNP allelic frequencies were plotted along the pseudo-chromosomes. This method proved to be efficient in identifying whole genome duplication (triploids) and aneuploidy. We also detected several loss of heterozygosity regions which may indicate small chromosomal deletions and/or inheritance of identical by descent regions from both parents. The SNP analysis was validated by flow cytometry and chromosome counts. The triploids were all derived from twin-embryo seeds. This is the first report on the efficiency and reliability of SNP array data for karyotyping oil palm chromosomes, as an alternative to the conventional cytogenetic technique. Information on the ploidy composition and chromosomal structural variation can help to better understand the genetic makeup of samples and lead to a more robust interpretation of the genomic data in marker.trait association analyses.

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Comparison of quantitative trait loci (QTLs) associated with yield components in two commercial Dura x Pisifera breeding crosses
By: MS. SITI HAZIRAH BINTI ZOLKAFLI
Publisher: Euphytica
Date: 9 May 2021

Abstract

The high yielding tenera is the commercial oil palm planting material of choice in Southeast Asia. Notwithstanding this, there is continuous effort to further improve the yield and one way to do this is by addressing the yield components (YCs). Using 4451 SNP and over 600 SSR markers, this study revealed quantitative trait loci (QTL) associated with YCs in two breeding populations, a Deli dura.×Yangambi pisifera (P2) and a Deli dura.×AVROS pisifera (KULIM DxP). Thirteen and 29 QTLs were identified in P2 and KULIM DxP, respectively. They were compared to other YC-linked QTLs reported previously for different genetic backgrounds by mapping the QTL-linked markers to the oil palm genome. The comparison revealed four common chromosomes containing QTLs influencing various YCs. The results reveal the possible presence of closely linked loci or pleiotropic genes influencing YCs in oil palm. Exploiting the genome data has also facilitated the discovery of candidate genes within or near the QTL regions including those related to glycosylation, fatty acid and oil biosynthesis, and development of flower, seed and fruit.

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Identification of oil palm root-specific genes through mining of RNA-seq data and RT-qPCR analysis
By: MDM. SITI MASURA SUBHI
Publisher: JOPR
Date: 30 Aug 2021

Abstract

Identification of novel genes that are specifically expressed in root is essential for isolation and characterisation of root-specific promoters. Mining the transcriptome of various oil palm tissue-specific data generated from ribonucleic acid-sequencing (RNA-Seq) technology has enabled the discovery of rootspecific genes. A total of seven candidates of root-specifically or preferentially expressed genes were selected from RNA-Seq analysis, and the gene expression profiles were validated using real-time quantitative polymerase chain reaction (RT-qPCR). The relative fold change of transcript expression in RT-qPCR was statistically analysed by comparing with root tissues at the in vitro culture stage (RS1). Results showed that the transcript annotated as an oil palm metallothionine (EgMT) gene was significantly upregulated at around 7 to 170-fold across the different developmental stages of root tissues. A proline-rich protein (EgPRP1) transcript was also significantly upregulated by about 7 to 55-fold. Both EgMT and EgPRP1 transcripts had relatively low expressions in the other tissues studied. The high levels of expression of EgMT and EgPRP1 in roots highlighted the genes. promoter.s potential to regulate a strong expression level of transgenes in a root-specific manner.

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Characterisation of oil palm acyl-CoA-binding proteins and correlation of their gene expression with oil synthesis
By: MS. NADZIRAH BINTI AMIRUDDIN
Publisher: Plant and Cell Physiology
Date: 27 Dec 2019

Abstract

Acyl-CoA-binding proteins (ACBPs) are involved in binding and trafficking acyl-CoA esters in eukaryotic cells. ACBPs contain a well-conserved acyl-CoA-binding domain. Their various functions have been characterized in the model plant Arabidopsis and, to a lesser extent, in rice. In this study, genome-wide detection and expression analysis of ACBPs were performed on Elaeis guineensis (oil palm), the most important oil crop in the world. Seven E. guineensis ACBPs were identified and classified into four groups according to their deduced amino acid domain organization. Phylogenetic analysis showed conservation of this family with other higher plants. All seven EgACBPs were expressed in most tissues while their differential expression suggests various functions in specific tissues. For example, EgACBP3 had high expression in inflorescences and stalks while EgACBP1 showed strong expression in leaves. Because of the importance of E. guineensis as an oil crop, expression of EgACBPs was specifically examined during fruit development. EgACBP3 showed high expression throughout mesocarp development, while EgACBP1 had enhanced expression during rapid oil synthesis. In endosperm, both EgACBP1 and EgACBP3 exhibited increased expression during seed development. These results provide important information for further investigations on the biological functions of EgACBPs in various tissues and, in particular, their roles in oil synthesis.

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Transcriptome analysis across various mesocarp developmental stages of MPOB-Angola dura
By: MDM. PRISCILLA ELIZABETH MORRIS
Publisher: JOPR
Date: 30 June 2020

Abstract

Angolan germplasm materials are being evaluated for their potential use in oil palm breeding programmes. Large fruits characteristic of some Angola dura palms have provided breeders with a source of favourable traits for introgression into the current planting materials. With the aim of understanding molecular regulation during mesocarp development, maturation and ripening of Angola dura palms, efforts were initiated to profile the expression of transcripts across nine different developmental stages of mesocarp tissues. A 36 675 total gene set was identified from ribonucleic acid (RNA)-Sequencing with 24 226 transcripts successfully annotated with the Plant Reference Sequence (RefSeq) Database using BLASTX, while 12 449 transcripts had no hit to any known genes. Pairwise T-test was performed using TIGR Multiexperiment Viewer and a total of 21 261 transcripts were identified as significant across all the pairwise comparisons. BLAST2GO analysis resulted in the annotation of 13 996 unigenes with various gene ontology (GO) terms. Transcripts associated with lipid metabolic process were highly expressed during lag phase preceding the lipid biosynthesis [10 to 12 weeks after anthesis (WAA)] and fruit maturation (18 to 20 WAA) stages. Further annotation of the unigenes with Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway resulted in the identification of 279, 757 and 142 transcripts related to lipid metabolism, carbohydrate metabolism and hormone metabolism, respectively. Detailed analysis of the expression data revealed that certain transcripts such as KAS I, FATA, DGAT, WRI1 and bZIP showed unique expression profiles in the MPOB-Angola dura as compared to the published data. The availability of these transcriptome datasets gives an insight into the transcriptional mechanisms controlling the Angolan dura fruit development, maturation and ripening.

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Variation for heterodimerization and nuclear localization among known and novel oil palm SHELL alleles
By: DR. RAJINDER SINGH
Publisher: New Phytol.
Date: 21 Dec 2019

Abstract

Oil palm breeding involves crossing dura and pisifera palms to produce tenera progeny with greatly improved oil yield. Oil yield is controlled by variant alleles of a type II MADS-box gene, SHELL, that impact the presence and thickness of the endocarp, or shell, surrounding the fruit kernel. We identified six novel SHELL alleles in noncommercial African germplasm populations from the Malaysian Palm Oil Board. These populations provide extensive diversity to harness genetic, mechanistic and phenotypic variation associated with oil yield in a globally critical crop. We investigated phenotypes in heteroallelic combinations, as well as SHELL heterodimerization and subcellular localization by yeast two-hybrid, bimolecular fluorescence complementation and gene expression analyses. Four novel SHELL alleles were associated with fruit form phenotype. Candidate heterodimerization partners were identified, and interactions with EgSEP3 and subcellular localization were SHELL allele-specific. Our findings reveal allele-specific mechanisms by which variant SHELL alleles impact yield, as well as speculative insights into the potential role of SHELL in single-gene oil yield heterosis. Future field trials for combinability and introgression may further optimize yield and improve sustainability.

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Candidate genes linked to QTL regions associated with fatty acid composition in oil palm
By: MDM. TING NGOOT CHIN
Publisher: Biologia
Date: 13 July 2020

Abstract

The present study searched for candidate genes in five linkage groups (LGs) - T2, T3, OT4, OT6 and T9 hosting the QTLs associated with iodine value (IV) and fatty acid composition (FAC) in an oil palm interspecific hybrid population. Each of the five LGs was successfully anchored to its corresponding chromosomal segment where, a wider repertoire of candidate genes was identified. This study further revealed a total of 19 candidate genes and four transcription factors involved in biosynthesis of fatty acids, lipids (including triacylglycerol) and acetyl-CoA, glycosylation and degradation of fatty acids. Their possible involvement in regulating the levels of saturation are discussed. In addition, 22 candidate genes located outside the QTL intervals were also identified across the interspecific hybrid genome. A total of 92 SSR markers were developed to tag the presence of these candidate genes and 50 were successfully mapped onto their respective positions on the genome. The data obtained here complements the previous studies, and collectively, these QTL-linked candidate gene markers could help breeders in more precisely selecting palms with the desired FAC.

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High Impact

On the Shelf

PalmXplore: oil palm gene database
Date: 18 September 2018
The oil palm genome revolution
Date: 13 December 2017