Purification and characterization of soluble peroxidase from oil palm (Elaeis guineensis Jacq) leaf

Soluble peroxidase (POD) from oil palm leaf was purified by (NH(4))(2)SO(4) precipitation, anion exchange chromatography and molecular exclusion chromatography. The purification grade obtained was 429 yielding 54% of the enzyme activity. Electrophoresis of purified enzyme under denatured conditions revealed M(r) of 48+/-2 kDa. It has an optimum pH of 5 and it exhibited very high pH and thermal stabilities. K(m) for guaiacol, ABTS and pyrogallol were 3.96, 1 and 0.84 mM, respectively. Immunocytochemical localization studies showed that soluble POD was mainly located in the vascular bundles and epidermis of leaf.     

Cryopreservation of oil palm (Elaeis guineensis Jacq.) somatic embryos involving a desiccation step

Summary The standard cryopreservation process previously developed for oil palm clones using shiny white, finger-like somatic embryos could be applied in some cases to standard cultures. Its efficiency was markedly improved by completing the 7-day pregrowth period on 0.75 M sucrose by an additional dehydration period carried out either by placing the embryos in the air current of the laminar flow cabinet or in an air tight box containing silica gel. This improved process was successfully applied to 7 different clones. It will facilitate the routine uof cryopreservation for oil palm cultures.     

Effects of tissue culture conditions during embryoid multiplication on the incidence of ``mantled' flowering in clonally propagated oil palm

New and established embryoid lines of oil palm (Elaeis guineensis Jacq.) clones, classified with regard to the expected risk of mantled flowering, were included in experiments to determine to what extent culture conditions during 48 weeks of embryoid multiplication could influence the incidence and severity of mantled flowering. Variables tested included clone risk status, duration of transfer interval, and plant growth regulator composition of the culture medium. Clones classified as high risk at the outset gave a significantly higher incidence of mantled flowering in the field than clones classified as low/medium risk, confirming that data on terminal inflorescences produced in vitro allows effective screening of material with regard to the risk of mantled flowering. The incidence of mantled flowering ranged from 0 to 100% depending on risk status of the clones, and the treatments applied. In general, a relatively long transfer interval (8 weeks) and a high auxin/cytokinin ratio resulted in the lowest incidence of mantled flowering with all types of material. Reducing the transfer interval down to 2 or 4 weeks, and/or using media with relatively high concentrations of kinetin (0.25 mg l^–1), and low concentrations of naphthalene acetic acid (0 or 0.1 mg l^–1), resulted in a high incidence of mantled flowering (above 30%), even with low/medium risk clones. Exclusion of plant growth regulators from the embryoid multiplication medium did not prevent some mantled flowering (12%) of new embryoid lines of low/medium risk clones following embryoid multiplication on a 4 week transfer interval, and a much higher incidence of mantling (above 90%) of lines from high risk clones.     

Environmental regulation of sex determination in oil palm: current knowledge and insights from other species

BACKGROUND: The African oil palm (Elaeis guineensis) is a monoecious species of the palm subfamily Arecoideae. It may be qualified as 'temporally dioecious' in that it produces functionally unisexual male and female inflorescences in an alternating cycle on the same plant, resulting in an allogamous mode of reproduction. The 'sex ratio' of an oil palm stand is influenced by both genetic and environmental factors. In particular, the enhancement of male inflorescence production in response to water stress has been well documented. SCOPE: This paper presents a review of our current understanding of the sex determination process in oil palm and discusses possible insights that can be gained from other species. Although some informative phenological studies have been carried out, nothing is as yet known about the genetic basis of sex determination in oil palm, nor the mechanisms by which this process is regulated. Nevertheless new genomics-based techniques, when combined with field studies and biochemical and molecular cytological-based approaches, should provide a new understanding of the complex processes governing oil palm sex determination in the foreseeable future. Current hypotheses and strategies for future research are discussed.     

油棕等热带植物DXS基因的生物信息学分析

油棕等热带植物含有丰富的胡萝卜素和维生素E等类异戊二烯物质,类胡萝卜素和甾醇等类异戊二烯物质在植物生命活动中扮演重要角色,并且对保护人类健康具有重要意义,MEP途径是合成类异戊二烯的重要途径之一。DXS是MEP途径中的第一个限速酶,其功能在油棕等热带植物中极其保守。为了弄清油棕等热带植物DXS的结构和功能特点,该研究利用生物信息学工具和软件对以油棕等热带植物类异戊二烯合成关键基因DXS为对象,进行核酸和氨基酸序列的理化性质、蛋白质结构以及功能结构域等分析,探讨了不同物种间的亲缘关系。结果表明:DXS基因起始密码子均为ATG,终止密码子则分为TAG、TAA和TGA,DXS蛋白质属于不具有信号肽的亲水性蛋白,可能作为转运蛋白在叶绿体基质中发挥作用,未发现明显的跨膜结构域,磷酸化位点有36个,其中丝氨酸、苏氨酸和酪氨酸位点分别为17、11和8个,无规则卷曲和α-螺旋是蛋白质二级结构主要的结构元件,三级结构预测具有DXS酶特征,硫胺素焦磷酸盐结合位点和PLN02582保守结构域,不同植物DXS功能结构域非常保守,可以作为判断不同物种间亲缘关系的重要依据。该研究结果为油棕等热带植物DXS的结构、功能分析和利用提供了进一步的信息,为其品质性状分子机制研究及遗传改良奠定了基础。     

Oil palm (Elaeis guineensis) protoplasts: isolation, culture and microcallus formation

Procedures are deseribed for the efficient isolation of protoplasts from a variety of oil palm (Elaeis guineensis Jacq.) tissues. Various factors including donor source, composition of enzyme mixture and culture medium affected the yield and viability of the protoplasts Polyembryogenic cultures of oil palm were the most suitable starting material in terms of yield, viability and metabolic competence. Pectolyase Y-23 in association with cellulase and hemicellulase was required for the efficient release of protoplasts from the oil palm tissues. Limited cell division to form microcallus was observed at very low frequency (<0.01%) when glutathione and catalase were incorporated in the culture medium.Abbreviations 2,4-d dichlorophenoxyacetic acid - DTT dithiothreitol - MES 2[N-morpholino] ethanesulphonic acid - NAA 1-naphthalene acetic acid - PVP polyvinylpyrrolidone     

Assessment of nuclear,mitochondrial and chloroplast RFLP markers in oil palm (Elaeis guineensis Jacq.)

A variety of DNA probes was used to screen a diverse set of oil palm accessions in order to identify markers with a utility in genotype discrimination. This survey included samples of the commercial oil palm native to Africa (Elaeis guineensis Jacq.), the closely-related South American species [E.oleifera (HBK) Cortes] and inter-specific hybrids of the two. Of 106 major chloroplast bands none showed differences between E. guineensis and E. Oleifera. Mitochondrial and ribosomal probes were more informative inter-specifically (the former allowing identification of the maternal inheritance of mitochondria) and may be useful in hybrid breeding programmes; however, they were unable to identify polymorphism within E. guineensis. In contrast, low-copy nuclear genomic clones were able to identify intra-specific variation, though in most cases they revealed a relatively small number of allelic variants. One DNA probe showed a much larger number of band variants, revealing ten patterns amongst 13 E. guineensis accessions, and should prove useful in genetic fingerprinting and evaluation of oil-palm germplasm collections.     

High density SNP and SSR-based genetic maps of two independent oil palm hybrids

Background

Oil palm is an important perennial oil crop with an extremely long selection cycle of 10 to 12 years. As such, any tool that speeds up its genetic improvement process, such as marker-assisted breeding is invaluable. Previously, genetic linkage maps based on AFLP, RFLP and SSR markers were developed and QTLs for fatty acid composition and yield components identified. High density genetic maps of crosses of different genetic backgrounds are indispensable tools for investigating oil palm genetics. They are also useful for comparative mapping analyses to identify markers closely linked to traits of interest.

Results

A 4.5 K customized oil palm SNP array was developed using the Illumina Infinium platform. The SNPs and 252 SSRs were genotyped on two mapping populations, an intraspecific cross with 87 palms and an interspecific cross with 108 palms. Parental maps with 16 linkage groups (LGs), were constructed for the three fruit forms of E. guineensis (dura, pisifera and tenera). Map resolution was further increased by integrating the dura and pisifera maps into an intraspecific integrated map with 1,331 markers spanning 1,867 cM. We also report the first map of a Colombian E. oleifera, comprising 10 LGs with 65 markers spanning 471 cM. Although not very dense due to the high level of homozygosity in E. oleifera, the LGs were successfully integrated with the LGs of the tenera map. Direct comparison between the parental maps identified 603 transferable markers polymorphic in at least two of the parents. Further analysis revealed a high degree of marker transferability covering 1,075 cM, between the intra- and interspecific integrated maps. The interspecific cross displayed higher segregation distortion than the intraspecific cross. However, inclusion of distorted markers in the genetic maps did not disrupt the marker order and no map expansion was observed.

Conclusions

The high density SNP and SSR-based genetic maps reported in this paper have greatly improved marker density and genome coverage in comparison with the first reference map based on AFLP and SSR markers. Therefore, it is foreseen that they will be more useful for fine mapping of QTLs and whole genome association mapping studies in oil palm.

Electronic supplementary material

The online version of this article (doi:10.1186/1471-2164-15-309) contains supplementary material, which is available to authorized users.     

油棕鲜果穗产量构成因素的相关性和回归分析

为明确油棕鲜果穗产量构成因素之间的关系,利用相关性、回归和通径等分析方法,对58株油棕单株鲜果穗产量与其它性状相关性进行了研究。结果表明:油棕鲜果穗产量与鲜果穗重和每株果穗数的相关性最为密切。另外,在油棕高产品种选育过程中,应着重对平均果穗重、每株果穗数、果实大小和含油量等性状进行选择,并综合权衡这些产量性状之间的相互作用。产量性状变异和相关性分析表明,平均种壳厚度变异程度最大(88.34%),平均果长变异最小(11.99%),鲜果穗产量与鲜果穗重、每株果穗数、平均果重呈极显著正相关关系(0.882**,0.714**,0.439**),与平均果长呈显著正相关关系(0.334*)。多元线性回归和通径分析结果表明,通过比较多元线性回归方程的相关参数,建立了可实用的最优多元线性回归方程x_1=-281.511+2.787x_4+3.455x_5-2.672x_6+0.411x_7+6.690x_8+3.664x_9,平均鲜果穗重和每株果穗数对单株鲜果穗产量的直接作用最大(0.670,0.439),其它性状对单株产量的直接作用较小,平均果重和平均果长对单株鲜果穗产量的间接作用最大(0.335,0.322)。该研究结果为油棕高产品种选育提供了依据。     

The shoot apical meristem of oil palm (Elaeis guineensis; Arecaceae): developmental progression and dynamics

Background and Aims

Oil palm, an unbranched perennial monocotyledon, possesses a single shoot apical meristem (SAM), which is responsible for the initiation of the entire above-ground structure of the plant. To compare the palm SAM structure with those of other monocots and to study variations in its structure throughout the life of the plant, its organization was characterized from the embryonic stage to that of the reproductive plant.

Methods

SAM structure was studied by a combination of stained histological sections, light and confocal microscopy, and serial section-based three-dimensional reconstructions.

Key Results

The oil palm SAM is characterized by two developmental phases: a juvenile phase with a single tunica-corpus structure displaying a gradual increase in size; and a mature phase characterized by a stable size, a modified shape and an established histological zonation pattern. In mature plants, fluctuations in SAM shape and volume occur, mainly as a consequence of changes in the central zone, possibly in relation to leaf initiation.

Conclusions

Development of the oil palm SAM is characterized by a juvenile to mature phase transition accompanied by establishment of a zonal pattern and modified shape. SAM zonation is dynamic during the plastochron period and displays distinct features compared with other monocots.     

Growth and biochemical profiling of artificially associated micropropagated oil palm plantlets with Herbaspirillum seropedicae

The challenges of various biotic and abiotic stresses can imperil the growth of micropropagated plantlets either direct or indirectly. Hence, in this study, a mutual relationship was established between diazotrophs and micropropagated plantlets to enhance plant growth and development. Artificial symbiosis was created for different inoculums of Herbaspirillum seropedicae (Z78), namely sonicated cells, broth culture, and pellet cells with micropropagated oil palm plantlets Elaeis guineensis Jacq. Results reveal significant differences on root volume, total protein content, and Brix value for Z78 broth culture treatment compared with plantlets treated with 25% N. High nitrogenase enzyme activities (6.7?×?10^?4?µmol?C₂H₄ g^?1?h^?1) and indole-3-acetic acid production (205.21?µmol (g?FW)^?1) were also detected on roots of plantlets treated with Z78 broth culture. These beneficial traits reviewed that the application of diazotrophs (Z78) in associative manner for micropropagated plantlets hold vast potential for promoting plant growth and plant’s healthiness.     

BA enhances the germination of oil palm somatic embryos derived from embryogenic suspension cultures

Embryogenic suspension cultures of oil palm ( Elaeis guineensis Jacq.) allow mass propagation of somatic embryos; however regeneration rates are low. Histological observations have revealed that shoot development might be limited by the absence of a caulinary meristem. The addition of 6-benzyladenine during development was found to induce shoot apex differentiation and thus increased germination rates, by up to 70%. However, multiple shoot formation was a consequence of a longer period of cytokinin supply during the development of the embryo. In contrast, a short period of culture on medium with 6-benzyladenine at the begining of embryo development was found to result in single shoot production.     

Characterization of oil palm MADS box genes in relation to the mantled flower abnormality

In vitro propagation of oil palm (Elaeis guineensis Jacq.) frequently induces a somaclonal variant called ‘mantled’ abnormality, in which the stamens of both male and female flowers are transformed into carpels. This leads to a reduced yield or complete loss of the harvest of palm oil. The high frequency of the abnormality in independent lines and the high reversal rate suggest that it is due to an epigenetic change. The type of morphological changes suggest that it involves homeotic MADS box genes that regulate the identity of the flower whorls. We have isolated a number of MADS box genes from oil palm inflorescences by a MADS box-directed mRNA display approach. The isolated partial cDNAs included genes that were likely to function at the initial stages of flowering as well as genes that may function in determination of the inflorescence and the identity of the flower whorls. For four genes that were homologous to genes known to affect the reproductive parts of the flower, full length cDNAs were isolated. These were a B-type MADS box gene which may function in the determination of stamen formation, a C-type gene expected to be involved in stamen and carpel formation, and two putative SEP genes which act in concert with the A-, B- and C-type MADS box gene in determining flower whorl formation. The B-type gene EgMADS16 was functionally characterized as a PISTILLATA orthologue; it was able to complement an Arabidopsis thaliana pi mutant. Whether EgMADS16, or any of the other EgMADS genes, are functionally involved in the mantled condition remains to be established.     

Phenology and growth adjustments of oil palm (Elaeis guineensis) to photoperiod and climate variability

Background and Aims

Oil palm flowering and fruit production show seasonal maxima whose causes are unknown. Drought periods confound these rhythms, making it difficult to analyse or predict dynamics of production. The present work aims to analyse phenological and growth responses of adult oil palms to seasonal and inter-annual climatic variability.

Methods

Two oil palm genotypes planted in a replicated design at two sites in Indonesia underwent monthly observations during 22 months in 2006–2008. Measurements included growth of vegetative and reproductive organs, morphology and phenology. Drought was estimated from climatic water balance (rainfall – potential evapotranspiration) and simulated fraction of transpirable soil water. Production history of the same plants for 2001–2005 was used for inter-annual analyses.

Key Results

Drought was absent at the equatorial Kandista site (0°55′N) but the Batu Mulia site (3°12′S) had a dry season with variable severity. Vegetative growth and leaf appearance rate fluctuated with drought level. Yield of fruit, a function of the number of female inflorescences produced, was negatively correlated with photoperiod at Kandista. Dual annual maxima were observed supporting a recent theory of circadian control. The photoperiod-sensitive phases were estimated at 9 (or 9 + 12 × n) months before bunch maturity for a given phytomer. The main sensitive phase for drought effects was estimated at 29 months before bunch maturity, presumably associated with inflorescence sex determination.

Conclusion

It is assumed that seasonal peaks of flowering in oil palm are controlled even near the equator by photoperiod response within a phytomer. These patterns are confounded with drought effects that affect flowering (yield) with long time-lag. Resulting dynamics are complex, but if the present results are confirmed it will be possible to predict them with models.     

Character interrelationships and path coefficient analysis for oil yield in the oil palm

Path coefficient analysis of eight yield components correlated with yield in 22 oil palm progenies showed that number of bunches per palm had the largest direct effect on oil yield followed single bunch weight and percent oil-to-mesocarp ratio.     

Differential Gene Expression and Characterization of Tissue-specific cDNA Clones in Oil Palm using mRNA Differential Display

The mRNA differential display method was utilized to study the differential expression and regulation of genes in two species of oil palm, the commercially grown variety Elaeis guineensis, var. tenera and the South American species, Elaeis oleifera. We demonstrated the differential expression of genes in the mesocarp and kernel at the week of active oil synthesis (15 week after anthesis) during fruit development as compare to the roots and leaves and the isolation of tissue-specific and species-specific cDNA clones. A total of eight specific cDNA clones were isolated and their specificities were confirmed by Northern hybridization and classified into three groups. Group one contains four clones (KT3, KT4, KT5 and KT6) that are kernel-specific for E. guineensis, tenera and E. oleifera. The second group represents clone FST1, which is mesocarp and kernel-specific for E. guineensis, tenera and E. oleifera. The third group represents clones MLT1, MLT2 and MLO1 that are mesocarp and leaf-specific. Northern analysis showed that their expressions were developmentally regulated. Nucleotide sequencing and homology search in GenBank data revealed that clones KT3 and KT4 encode for the same maturation protein PM3. While clones MLT1 and MLT2 encode for S-ribonuclease binding protein and fibrillin, respectively. The other clones (KT5, KT6, FST1 and MLO1) did not display any significant homology to any known protein.