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.     

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.     

Analysis of the genetic effects for several traits in oil palm (Elaeis guineensis Jacq.) populations. I. Population means

An oil palm experiment was set up in the Ivory Coast to compare the effects of crossing and selfing within two origins, Deli and La Mé, on the mean and the variability of Deli x Mé between-origin hybrids. The originality of the experiment lay in the crossing plan, which provided access to genetic parameters related to additivity, dominance and different components of epistasis. This first part covers the analysis of the components of the mean. The parents used were obtained from four palms, two from each origin. Those of La Mé origin were half-sibs. The common parent came from a wild stand in the Ivory Coast. Those of Deli origin were from two different populations bred in Southeast Asia for several generations from a narrow genetic base. These four parents gave rise to nine Deli x La Mé hybrid populations with double-cousintype links. The additive component is more important within the Deli origin than within the La Mé origin. This may be explained by the large genetic divergence between the two Deli parent palms. On the other hand, the additive^* additive epistasis is more substantial within the La Mé origin, probably because of inbreeding. The discussion concentrates on how this information should be used when choosing parents to be crossed and tested and to produce improved populations. The crossing plan proposed can be of general use and is suitable for other species in a reciprocal recurrent selection programme.     

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     

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.     

Application of X-ray microanalysis to cell suspensions of oil palm (Elaeis guineensis Jacq.)

X-ray microanalysis has been used to determine the elemental composition of oil-palm (Elaeis guineesis) cell suspensions without the use of cryoprotectants. Results based on individual cells were gathered over a typical growth cycle of 14 d. During the log phase (5–7 d) there is an increase in the number of cells containing high concentrations of both K (400 mmol kg^-1 dry weight) and P (400 mmol kg^-1 dry weight). Morphologically these cells had thin cell walls and were frequently joined to other cells (two to five cells per clump).     

RAPD linkage mapping of the shell thickness locus in oil palm (Elaeis guineensis Jacq.)

Shell thickness is an important trait in oil palm breeding programs and is the basis for the classification of the varieties of oil palm into the types dura, tenera and pisifera. This trait seems to be controlled by a single locus, with two alleles (sh ⁺ and sh ⁻) showing codominant expression. Two single-tree linkage maps were constructed for a maternal tenera (sh ⁺ sh ⁻) palm and for a paternal pisifera (sh ⁻ sh ⁻) palm using the pseudo-testcross mapping strategy in combination with RAPD markers through the analysis of an F₁ tenera×pisifera progeny. A total of 308 arbitrary primers were screened in a sample of eight F₁ plants and 121 markers were detected in a testcross configuration. An average of 1.66 polymorphic marker per selected primer were identified in this cross. At LOD 5.0 (with some few exceptions) and θ=0.25 the maternal tenera map included a total of 48 markers distributed in 12 linkage groups or pairs of markers (449.3 cM) while the paternal pisifera map included 42 markers distributed in 15 linkage groups or pairs of markers (399.7 cM). We used RAPD and bulked segregant analysis (BSA) to identify markers more tightly linked to the sh ⁺ locus. A total of 174 new primers not previously used in the linkage analysis were screened using bulks of DNA extracted from plants selected for the contrasting shell-thickness phenotypes. Two RAPD markers (R11–1282 and T19–1046) were identified to be linked on both sides of the sh ⁺ locus on linkage group 4. The estimated map distances from sh ⁺ to R11–1282 and to T19–1046 were 17.5 cM and 23.9 cM, respectively. The results demonstrate the usefulness of RAPD markers and the pseudo-testcross mapping strategy for developing genetic linkage information, and constitute an important step towards early marker-assisted selection for shell thickness in oil palm. Received: 21 February 1999 / Accepted: 29 April 1999     

Heritability of fresh fruit bunch yield and its components in the oil palm (Elaeis guineensis,Jacq.)

Summary Single-plant heritability estimates of 38.9%, 31.5% and 42.3% were obtained for number of bunches (NB), fresh fruit bunch yield (FFB) and mean bunch weight (MBW) respectively. Hybrid (family) mean heritability estimates for these traits were 88.9%, 90.5% and 96% respectively. Repeatability estimates for these traits were 33%, 11% and 8% for NB, FFB and MBW respectively. Evaluation of hybrid family mean for yield components appears feasible at the third or fourth year of data collection. Phenotypic and genotypic correlations between NB and FFB were 0.80 and 0.61 respectively; between NB and MBW, –0.41 and –0.16 respectively; and between FFB and MBW, 0.66 and 0.60 respectively. The hypothesis that increased FFB can be obtained by hybridization between parents with high NB and heavy MBW is supported by this correlation set.     

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.     

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.     

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。     

A new aspect of genetic diversity of Indonesian oil palm (Elaeis guineensis Jacq.) revealed by isoenzyme and AFLP markers and its consequences for breeding

Oil palm (Elaeis guineensis Jacq.) plays an important economic role in some countries of Southeast Asia like Indonesia, which is the world’s second producer of palm and palm kernel oil. The quality improvement of planting material needs a better understanding of the genetic relationships between genotypes from different populations used in the breeding programmes. In this study, 48 parents, representative of four populations used in Indonesian Oil Palm Research Institute (IOPRI) breeding programmes, were analysed with five selected AFLP primer pairs and four isoenzymatic systems. One hundred and fifty eight scorable band levels were generated of which 96 (61%) were polymorphic. AFLP allowed us to identify off–type descendants which were excluded from analysis. The use of unbiased Rogers distance clearly separated the four studied populations. The Neighbor-Joining method re-groups two African populations which are known as originating from different regions. Nevertheless, the variability revealed is in accordance with oil palm breeders’ knowledge. The results obtained with AFLP showed that the crosses among the African sub-population, which is excluded in oil palm reciprocal recurrent selection (RRS) breeding programmes, may be more interesting than the crosses between the African and the Deli populations. Received: 9 August 1999 / Accepted: 28 February 2000     

A modeling approach of the in vitro conversion of oil palm (Elaeis guineensis) somatic embryos

A mathematical model for the growth and conversion of somatic embryos was developed with the aim of monitoring the large scale production of oil palm microplants. The predicted biomass of somatic embryos obtained and subcultured (B _n ), together with the number of harvested shoots (Sh _n ) – two key parameters for production forecasts – have been modeled for seven different shoot harvesting procedures. For the four different clonal lines studied, observed differences between experimental B _n values at the end of each culture cycle and their theoretical counterpart generated by mathematical models were found to range between −30% to +14% at the end of the first 6-weeks culture cycle, then from −50% to +70% after the 6th subculturing operation (36 weeks). Concerning the predicted number of shoots harvested after conversion of somatic embryos (Sh _n ), average variations between experimental and theoretical values ranged between −45% and +41%. Predicted values for biomass (B _n ) between two culture cycles were found to vary slightly (+6% to +10%) indicating that the production of embryo biomass, as predicted by the model, was rather stable, for a given clonal line, from one 6-week cycle to another. The established model could thus be regarded as valid and the variations observed for B _n and Sh _n were found to be acceptable when compared to the those described by other models. Taken as a whole, predicted values for the two studied production parameters were in agreement with the corresponding experimental data (correlation=0.98).     

The histodifferentiation events involved during the acquisition and development of somatic embryogenesis in oil palm (Elaeis guineensis Jacq.)

Understanding the fate and dynamics of cells during callus formation is essential to understanding totipotency and the somatic embryogenesis (SE) mechanisms. In the present study, the histodifferentiation events involved during the acquisition and development of somatic embryogenesis in oil palm (Elaeis guineensis Jacq.) was investigated. Zygotic embryos were inoculated on SE induction medium, and at 14 days the first divisions of the procambial and perivascular cells were observed. This region progressed to the formation of meristematic masses at 21 days, indicating their procambial and perivascular origin. Primary calli emerged at 45 days of culture, followed by progression to embryogenic calli at 90 days. The formation of proembryos (PE) from the meristematic cells occurred at 135 days of cultivation. The PE were isolated from the tissue of origin by the slight thickening of the cell wall, indicating their unicellular origin. When transferred to the maturation phase, differentiation of the somatic embryos at different developmental stages (globular and torpedo) was observed. The differentiated somatic embryos presented protoderm, procambial strands and plumules. Afterwards, they were transferred to culture medium without growth regulators in which conversion of the somatic embryos from torpedo stage into plants was observed. These results enable a greater understanding of the SE process and plantlet formation in E. guineensis.     

Investigations into the late Pleistocene and Holocene history of vegetation and climate in Santa Catarina (S Brazil)

Palynological studies have been carried out on three highland peat bogs, and one situated on the Atlantic coastal plain. In the highlands, the late Pleistocene (14,000 - 10,000 uncal B.P.) vegetation was dominated by campos (grassland). Scattered stands of Araucaria forests were preserved in deep valleys. In the region of the sites at Morro da Igreja and Serra do Rio Rastro, the dominance of campos vegetation continued until about 1000 B.P. while at the Serra da Boa Vista site there was an expansion of Atlantic pluvial forest elements followed by Araucaria forests at the beginning of the Holocene. A general expansion of A. angustifolia, clearly related to a change towards an increasingly moist climate, can be dated to the present millenium. On the coastal plains, the late Pleistocene vegetation was dominated by Myrtaceae which were replaced by tropical taxa in the Holocene. The lowland profile (Poço Grande) also covers part of the upper Holocene, where the rich flora of the Atlantic pluvial forests can be characterized by taxa including Alchornea, Urticales and Rapanea. Close to the coring site, there was a repeated alternation between two different dune communities (4840 - 4590 B.P.), followed by a lake stage with aquatic plant succession (4590 - 4265 B.P.), plant communities dominated by Rapanea (4265 - 4230 B.P.) and the spread of Alchornea (4230 - 3525 B.P.). Late Pleistocene climate conditions (14,000 - 10,000 B.P.) can be described as cold and relatively dry, possibly including an equivalent of the Younger Dryas period. In the Holocene, there were changes from a warm and drier climate (10,000 -3000 B.P.) to a cool and more moist regime (ca. 3000 -ca. 1000 B.P.) and finally to a cool and very moist period (from around 1000 B.P.).     

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。     

Evidence for an interaction effect during <Emphasis Type="Italic">in vitro</Emphasis> rooting of oil palm (<Emphasis Type="Italic">Elaeis guineensis</Emphasis> Jacq.) somatic embryo-derived plantlets

In vitro rooting of oil palm shoots derived from somatic embryos was achieved through a single-phase protocol in which three shoots are cultured in the same culture tube on an α-naphtaleacetic acid-enriched culture medium. Rooting performance was dependent on both the genetic origin and initial size of the shoot explants. All shoots from a given tube showed a tendency to give roots of the same type, independent of the original size of the explant. Whatever the clonal line, longer-size shoots (L-type: >9 cm) showed higher rooting rates than medium-size (M-type: 7–9 cm) and short-size ones (S-type: 5–7 cm). When groups of three shoots from the same clonal line were rooted together in the same culture tube, the combination of plant size within the group impacted overall quality of rooting. Within triplets of shoots containing more than one short individual, the probability of obtaining adequate rooting was low. Similarly, when more than one long shoot was included in the triplet rooting, quality was also poor. By avoiding such combinations, the rate of well-rooted plantlets increased by 25%, with a maximum of 66% when triplets of S/M/L combination were used. Smaller shoots, which usually showed poor rooting performance, were therefore found to benefit from the presence of their neighbors. This interaction between the sizes of individuals in a given tube was found to be associated with a within-tube correlation effect, a phenomenon previously described as “event coupling,” which was estimated using a distorted binomial-type distribution of probabilities. The resulting calculation of a coupling factor (average r = 0.60) explains the behavior of shoots within the same culture tube and their average rooting performance. Modeling of the interactions that occurred during in vitro rooting is described here and is recommended for improvement of this critical step in micropropagation.     

The emission of mugwort pollen (Artemisia vulgaris L.) and its flight in the air

Summary Mugwort pollen flight and pollen emission are characterized by a distinct biological rhythm with emission in the early morning hours (6:00–11:00 a.m. CEST). Pollen traps at roof level monitor the daily and yearly variation of mugwort pollen flight later and in lower quantities than those installed at ground level because of the different daily variation of convection at various air levels. The daily variation of mugwort pollen flight can be described by mathematical functions. Because of these significant differences between the catch at different levels, the supposed high allergic potential of mugwort has to be discussed.