Composition, Degradation and Utilization of Endosperm During Germination in the Oil Palm (Elaeis guineensis Jacq.)

The insoluble carbohydrate and lipid fractions, and -D-galactosidase,ß-D-mannosidase and isocitrate lyase activities werestudied in the various tissues of oil palm (Elaeis guineensisJacq.) kernels prior to and during germination. In ungerminatedkernels insoluble carbohydrate and lipid constituted 36 and47% of endosperm dry weight respectively. During germinationthe thick endosperm cell walls became markedly thinner, concurrentwith a significant decrease in the percentage of insoluble carbohydrateand an increase in -galactosidase and ß-mannosidaseactivity in both degraded and residual endosperm. The proportionof lipid in degraded endosperm also increased significantly.The insoluble carbohydrate appears to be a galactomannan locatedin the secondary walls of the endosperm. No galactomannan wasdetected in oil palm embryos or haustoria. Isocitrate lyasewas present in, and confined to, tissues of the haustorium ofgerminating kernels. The enzyme was not active in endospermat any stage of germination, nor was it active in embryos beforeor at the end of imbibition. The results suggest that galactomannan is the second largestcomponent of oil palm endosperm and that it is utilized morerapidly than lipid during the early stages of germination. Thefact that isocitrate lyase activity is confined to the haustoriumsuggests that in Elaeis gluconeogenesis, the conversion of triglycerideto carbohydrate, takes place entirely within the cotyledon ofthe seed. Elaeis guineensis, galactomannan, galactosidase, germination, isocitrate lyase, mannosidase, oil palm     

Storage of Pollen Grains in Organic Solvents: Effect of Organic Solvents on Leaching of Phospholipids and its Relationship to Pollen Viability

In vitro germinability and membrane integrity (as revealed bythe fluorochromatic reaction (FCR) test) of pollen grains ofCrotalaria retusa L. stored in various organic solvents forsix months at –20±2 °C were studied and correlatedwith leaching of lipids, phospholipids, sugars and free aminoacids from pollen grains into organic solvents during storage.Pollen grains stored in organic solvents with low dielectricconstants (a measure of their non-polar nature), such as hexane,cyclohexane and diethyl ether, showed high scores for germinationand FCR and very little leaching of phospholipids, sugars andamino acids. Pollen grains stored in solvents with high dielectricconstants (a measure of their polar nature) such as isopropanoland methanol did not show germination or positive FCR scores,but showed extensive leaching of phospholipids, sugars and freeamino acids. The viability of pollen grains stored in organicsolvents seems to be determined largely by the effect of theorganic solvents on pollen phospholipid composition, which inturn affects membrane integrity and consequently pollen viability. Crotalaria retusa, organic solvents, pollen storage, viability, phospholipids     

Morphogenetic Potential of Embryo- and Seedling-Derived Callus of Elaeis guineensis Jacq. var. pisifera Becc.

The oil palm of commerce, Elaeis guineensis (tenera), derivesfrom hybridization of variety dura x pisifera. Germ plasm ofpisifera is limited, however, because of varying degrees offemale sterility. Efforts to increase the range of availablepisifera male germ plasm have thus far been limited to fertilepisiferas but it is anticipated that clonal multiplication ofembryos and explanted organs from less female-fertile, but nonethelessfertile, male, plants could play a significant role in breedingprogrammes. Callus has been produced from mature pisifera embryosand leaf explants from young plantlets using a half-strengthMurashige and Skoog medium supplemented with inositol, caseinhydrolysate, activated charcoal and varying concentrations ofauxins. After sub-culture on media of similar composition, organizedstructures can develop. Those which form in stale nutrient media(e.g. left in the same medium for up to 3 months) give riseto embryonal structures which do not readily develop furtherand can be regarded as neomorphs. If callus once formed is transferredto media with lower auxin concentrations (40–0 mg l^–1)embryonal buds and well-formed shoots are produced; additionof gibberellic acid (GA₃) fosters the production of well-organizedshoots accompanied by roots. Elaeis guineensis var pisifera, oil palm, tissue culture, micropropagation, embryo development, morphogenetic potential, callus     

Vibrating probe measurement of ionic currents around developing embryo of oil palm (Elaeis guineensis Jacq.)

The current patterns around zygotic embryos of the oil palmembryo (Elaeis guineensis Jacq.) were investigated. Ionic currentsaround the embryo were measured at different stages in its developmentusing a two-dimensional vibrating probe system. The averagecurrent density was found to be in the order of 1–µAcm^–2. In the early developmental stage, the current wasfound entering the cotyledon and leaving the radicle. Both themagnitude and direction of this current changed when embryosat different developmental stages were observed. The currentswere found to enter the region in the process of differentiationor elongation, and in some cases this could be the reverse ofthe current direction in the preceding stage. Within one ofthe stages of the embryos, current density was correlated withthe rate of elongation. A very large inward current (up to 20µAcm^–2) was also detected at the point where the shoot wasbreaking through the surface. This was probably caused by theso-called ‘injury current’. Key words: Ionic currents, vibrating probe, oil palm embryo, E. guineensis, injury current     

A Model of the Effect of Temperature and Moisture on Pollen Longevity in Air-dry Storage Environments

Data on the survival of pollen ofTypha latifoliaL. stored forup to 261 d over seven different saturated salt solutions (providing0.5 to 66% relative humidity) and six different constant temperatures(from -5 to +45 °C) were analysed to quantify the effectof air-dry storage environment on pollen longevity. Pollen survivalcurves conformed much more closely to negative cumulative normaldistributions than to negative exponential relations. Estimatesofp₅₀(storage period required to reduce pollen viability to50%), provided by negative cumulative normal distributions,were available from 37 different storage environments in whichpollen viability was reduced below 50%. Once observations at0.5% and 5.5% relative humidity were excluded from analysis,there was a negative logarithmic relation between these estimatesof longevity and pollen moisture content (%, wet basis) anda curvilinear semi-logarithmic relation between longevity andtemperature. When the negative logarithmic relation betweenlongevity and moisture content was replaced by a negative semi-logarithmicrelation between longevity and the relative humidity of thestorage environment the resultant model was less satisfactory,principally because pollen longevity over saturated solutionsof calcium nitrate (43–62% relative humidity) and sodiumnitrite (60–66% relative humidity) were consistently greaterand smaller, respectively, than fitted values. Notwithstandingthese errors, comparison between the fitted relations and observationsat the two lowest relative humidities provided estimates ofthe lower-relative-humidity limits to these relations. Theseprovisional estimates varied with storage temperature beinglowest at 25 °C (<5.5% relative humidity). However, therewas no linear trend to that variation (P>0.25): the meanestimate was 11.9 (s.e.=1.4)%. The considerable similaritiesamong models of pollen longevity in air-dry storage, and theirestimated lower limits, and those developed previously for orthodoxseeds and spores are discussed.Copyright 1999 Annals of BotanyCompany. Typha latifoliaL., pollen, storage, survival, longevity, relative humidity, moisture content, temperature.     

Pollination and Pollen-pistil Interaction in Oil Palm, Elaeis guineensis

Structural and cytochemical aspects of the pistil and detailsof pollination and pollen-pistil interaction were investigatedin the African oil palm (Elaeis guineensis Jacq.), an importantperennial oil crop. The stigma is trilobed, wet and papillate.The branched papillae are confined to a narrow linear zone oneach stigmatic lobe. Each stigmatic lobe harbours a deep stigmaticgroove, which runs adaxially along the surface. The stigmaticgroove is bordered by a well-defined layer of glandular cells,each of which has a pectinaceous cap on the inner tangentialwall. The style is hollow. The canal cells show thickeningson the inner tangential wall. The stigmatic groove and stylarcanal contain an extracellular matrix secreted by the canalcells which is rich in proteins, acidic polysaccharides andpectins. The canal cells at the base of the style are papillateand loosely fill the stylar canal. The stigma becomes receptivewhen the stigmatic lobes separate, and remains so for 24 h.Pollination is mediated by weevils as well as by the wind. Undernatural conditions the pollination efficiency was 100%. Pollinationinduces additional secretion in the stigmatic groove and stylarcanal. During post-pollination secretion, the pectinaceous capsof the cells lining the stigmatic groove are degraded. Pollengrains germinate on the stigmatic papillae and tubes grow onthe surface of the papillae, entering the stigmatic groove andadvancing along it into the stylar canal to eventually gainaccess to the locules. Pollen tubes are seen in the ovules 18–20h after pollination. Copyright 2001 Annals of Botany Company Arecaceae, Elaeis guineensis, African oil palm, pollination, stigmatic grove, stylar canal, Tenera hybrid, weevil     

Identification of p.Methoxyallybenzene in the Pollen of the Oil Palm Elaeis guineensis Jacq.

The lipid extract prepared from the pollen of the West African,oil palm, Elaeis guineensis, was found to contain p-methoxyallylbenzenein substantial amount. The pure substance after isolation bymeans of preparative gas-liquid chromatography and steam distillationwas characterized by using a combination of g.l.c.-mass spectrometry,infrared spectrometry, and chemical reactions. Mass spectrometrygave a spectrum with a parent ion at m/e 148 corresponding tothe molecular weight and fragmentation ions at m/e 133, 121,117, 105, 91, and 77. The structure was further confirmed bymeans of the infrared spectrum which showed major peaks at 1250,920, and 815 cm^–1 corresponding to a CH₃O group, a 1,4-substitutedaromatic ring, and a RCH=CH₂ group respectively. Its chemicaland physical properties (hydrogenation, oxidation, etc.) werefound to be similar to those of its positional isomer, p-methoxy--phenylpropene.The physiological and economic importance of the compound arediscussed.     

The Effects of Soil Water and Atmospheric Vapour Pressure Deficit on Stomatal Behaviour and Photosynthesis in the Oil Palm

The oil palm (Elaeis guineensis Jacq.) maintains a large leafarea throughout the year, but its productivity is limited bya low rate of dry matter production per unit leaf area. Stomatalclosure, at times of low soil water availability and high atmosphericvapour pressure deficit, is an important factor limiting photosynthesisand hence dry matter production. In this paper, laboratory andfield data are used to prepare a model of the relationshipsbetween net photosynthetic rate and stomatal conductance, andbetween stomatal conductance and environmental variables. Resultsshow that high atmospheric vapour pressure deficits may limitproduction even in parts of the world where oil palms are notnormally considered to suffer from water stress. The model canbe used to design and evaluate irrigation systems, and to helpquantify the potential value of oil palm genotypes with lowstomatal sensitivity to either VPD or available soil water foruse where irrigation is impractical. Key words: Elaeis guineensis Jacq., drought, irrigation, plant breeding     

Fertility of Deep-frozen Maize (Zea mays L.) Pollen

On average, 50 per cent of maize pollen grains can be kept viableand almost 30 per cent remain fertile for up to a year whenthe water content on a fresh weight basis is reduced to about30 per cent of the original and the pollen is stored at –76or –196 °C. Over this period no significant differencewas found between storage at either temperature. Zea mays L., maize, pollen, fertility, viability     

Breeding for Short-stemmed Oil Palm in Nigeria: Fatty Acids, their Significance and Characteristics

The fatty acids of the progenies arising from the first back-crossfrom Elaeis guineensis and Elaeis oleifera interspecific hybridsto E. guineensis have been characterized. Fatty-acid patternsshowed striking variability which indicated that factors governingfatty-acid inheritance are polygenic. Although segregation forindividual fatty acids had no relationship with the large numberof morphological characters observed, a definite upward trendin the percentage of unsaturated fatty acids was clearly showncompared to the parent palms. The commercial and domestic advantagesof unsaturated fatty acids are discussed. Elaeis guineensis, oil palm, breeding, fatty acid content     

Effects of Temperature on Pollen Viability in Mango cv. 'Kensington'

The response of pollen development to low or high temperatureregimes was studied to determine the conditions suitable forthe formation of fertile pollen in the mango cv. 'Kensington'.The phase most sensitive to the degree and duration of temperaturestress was that from meiosis to the pre-vacuolate microspore(about 3 d duration at 25/20 °C) though vacuolated microsporeswere also sensitive to low temperature. Night temperatures below10 °C resulted in pollen grains with a low viability (<50%). A temperature between 15 and 33 °C during the phasefrom meiosis to the pre-vacuolate microspore was optimum forpollen development (70-85% pollen viability). Analysis of field records showed a linear negative correlationbetween percentage of pollen viability and number of days whichhad a mean night temperature lower than 10 °C during theperiod from meiosis to early mature stage (y = 77·7-3·4x,r² = 0·60). The temperature sensitive phase was estimatedto begin 155 degree days D = [(T_max + T_min)/2 - 10] before anthesisand to end 78 degree days before anthesis. This equation maybe useful as a means of predicting pollen viability in the fieldfrom temperature records and thus fruit set, date of maturityand yield. It may also aid in the selection of areas for growingmangoes in marginal climates.Copyright 1994, 1999 Academic Press Mangifera indica L. mango, microsporogenesis, pollen development, viability, sterility, temperature     

Ripe pollen carbohydrate changes in Trachycarpus fortunei: the effect of relative humidity

Pollen of the palm Trachycarpus fortunei was kept at 25°C and relative humidities (RH) of 20, 55 and 98%. Changes in viability, water content and carbohydrates were measured over 2–17 days. Water content remained almost constant at 20 and 50% RH and increased dramatically at 98%. Pollen viability and germination rate remained almost constant over 14 days at 20% RH and decreased to about 2% after 7–9 days at 55% and to even less at 98% RH. Although the three experimental conditions were constant, qualitative and quantitative variations in pollen carbohydrates were recorded, even after pollen had lost its viability. The quantities of mono-, di- and polysaccharides varied with the period of pollen storage at the various RH. The greatest changes in glucose, fructose and sucrose content were recorded at 55 and 98% RH. At these relative humidities, maximum glucose and fructose content and minimum sucrose content occurred at maximum water content. Starch was not present in mature pollen but appeared and peaked after 7–9 days of pollen storage at 55 and 98%. Appearance of starch coincided with an increase in pectin content. PAS-positive cytoplasmic polysaccharides showed an increasing trend at 20% RH. A relation was found between pollen viability, water content and monosaccharide content. Pollen viability and germination capacity remained high at 20% RH for 14 days. At this relative humidity, pollen water, glucose and fructose contents remained almost constant, while sucrose reached its maximum value. The fluctuations of more complex carbohydrates (starch, pectins and PAS-positive cytoplasmic polysaccharides) were less easy to interpret. Changes observed under experimental conditions could simulate processes occurring in nature during pollen presentation and dispersal.     

Germination and Storage of Pollen of Phytolacca dodecandra L. (endod)

The effect of sucrose, H₂BO₃, KNO₃, Ca(NO₂)₂.4H₂O and MgSO₄.7H₂O on pollen germination of Phytolacca dodecandra L. (endod)in a liquid medium was investigated. Sucrose and H₃BO₃ werecritical to pollen germination. A concentration of 10% sucroseand 161.8 µm H₂BO₃ gave over 70% germination. The germinationof pollen was not enhanced by Ca(NO₃)₂.4H₂O, KNO₃ and MgSO₄.7H₂O.Endod pollen was dehydrated over CaCl₂ and stored in gelatincapsules in cryogenic vials at –175 °C, 1±1°C and 24±2 °C. The pollen moisture content atcollection was approx. 7.8% (f. wt basis) and dehydration overCaCl₂ reduced it to about 1.4%. Pollen stored at 1±1°C and –175 °C maintained viability for over 6months. Pollen stored at room temperature lost viability within4 weeks of storage. Pollination with cryopreserved pollen resultedin normal fruit set. Phytolacca dodecandra, endod, pollen germination, pollen storage     

Fruit Number in Relation to Pollen Production and Viability in Groundnut Exposed to Short Episodes of Heat Stress

Hot days and warm nights are important environmental factorslimiting fruit yields of groundnuts in the semi-arid tropics.The objective of the present research was to quantify the effectsof short episodes of heat stress on pollen production and viability,and fruit yield. Plants of cultivar ‘ICGV 86015’were grown at a day/night temperature of 28/22 °C from sowinguntil 9 d after flowering. Cohorts of plants were then exposedto a factorial combination of four day (28, 34, 42 and 48 °C)and two night (22 and 28 °C) temperatures for 6 d. Thereafter,all plants were maintained at 28/22 °C until final harvest9 d later. Number of flowers per plant (FN), the proportionof flowers setting pegs (fruit-set), the number of pegs andpods per plant (reproductive number, RN_t), pollen productionper flower and pollen viability were determined during the 6d stress period. There were strong negative linear relationsbetween day temperature over the range of 28 to 48 °C andFN (slope, -1.1 °C^-1), fruit-set (-2.8% °C^-1), RN_t(-0.90°C^-1), and pollen production (-390 °C^-1) and viability(-1.9% °C^-1). Warmer night temperature (28 vs. 22 °C)had no effect on FN, but reduced fruit-set (31 to 19%), RN_t(8to 5), and pollen production (4389 to 2800) and viability (49to 40%). There were no significant interactions between dayand night temperature. Reduced fruit-set was a consequence offewer pollen grains and reduced pollen viability. The thresholdday temperature for pollen production and viability was 34 °Cand there were strong negative linear relations between bothpollen production and pollen viability and accumulated temperature>34 °C. Copyright 1999 Annals of Botany Company Arachis hypogaea L., fruit-set, groundnut, heat-stress, peanut, pollen viability, pollen production, temperature.     

Water as a Storage Medium for Elaeis guineensis (pisifera) Seeds under Aseptic Conditions

Over 50 per cent germination has been obtained from Elaeis guineensisform pisifera seeds stored in unaerated sterile distilled waterfor 6 months. The moisture levels of the seeds and excised embryoswere of the same order (20–30 and 60–70 per cent,respectively) as those of fully imbibed fresh seeds. The implicationsof an apparent lower oxygen requirement by seeds stored underwater as against germinating seeds are discussed in the contextof the successful storage. Elaeis guineensis, pisifera, germination, seed dormancy, embryo     

Purification and characterization of 31-kDa palm pollen glycoprotein (Ela g Bd 31 K), which is recognized by IgE from palm pollinosis patients

A basic glycoprotein, which was recognized by IgE from oil palm pollinosis patients, has been purified from oil palm pollen (Elaeis guineensis Jacq.), which is a strong allergen and causes severe pollinosis in Malaysia and Singapore. Soluble proteins were extracted from defatted palm pollen with both Tris-HCl buffer (pH 7.8) and Na-acetate buffer (pH 4.0). The allergenic glycoprotein was purified from the total extract to homogeneity with 0.4% yield by a combination of DEAE- and CM-cellulose, SP-HPLC, and gel filtration. The purified oil palm pollen glycoprotein with molecular mass of 31 kDa was recognized by the beta1-2 xylose specific antibody, suggesting this basic glycoprotein bears plant complex type N-glycan(s). The palm pollen basic glycoprotein, designated Ela g Bd 31 K, was recognized by IgE of palm pollinosis patients, suggesting Ela g Bd 31 K should be one of the palm pollen allergens. The preliminary structural analysis of N-glycans linked to glycoproteins of palm pollens showed that the antigenic N-glycans having alpha1-3 fucose and alpha1-2 xylose residues (GlcNAc(2 to approximately 0)Man3Xyl1Fuc(1 to approximately 0)GlcNAc2) actually occur on the palm pollen glycoproteins, in addition to the high-mannose type structures (Man(9 to approximately 5)GlcNAc2).     

The significance of the oil palm (Elaeis guineensis Jacq.) in the late Holocene environments of west and west central Africa: A further consideration

Abundant archaeological evidence of the occurrence of the endocarp of the oil palm,Elaeis guineensis, in the rain forest and woodland savanna zones of west and central Africa from about 5000 B.P. has shown the tree to be an important element in the subsistence economy of the region; its pollen also has been recorded in most of the regional terrestrial sediments studied so far. The distinct and consistently sudden and more marked increases in this pollen during the late Holocene when compared with the late Tertiary and late Pleistocene frequencies strongly indicate that the late Holocene upsurges were due to both natural and human factors favourable for the expansion of this heliophytic tree. Reasons are given for suggesting that upsurges in oil palm pollen during the late Holocene period in this region can be used as indices of plant cultivation. While the oil palm is known from early Tertiary deposits in west Africa, its earliest palynological record from terrestrial sediments in the west central part dates back only to the early Holocene. More palynological studies of Tertiary and Quaternary terrestrial cores are required to establish with more certainty the antiquity ofE. guineensis in west central Africa.     

Lipid Composition and the Role of the Haustorium in the Young Seedling of the West African Oil Palm, Elaeis guineensis Jacq.

The lipid and fatty acid composition of the haustorium of thedeveloping seedling of the West African oil palm, Elaeis guineensisJacq. has been studied using the combined techniques of thin-layerand gas-liquid chromatography. In addition to triglycerides,which represented over 75 per cent of the total lipids, therewere present small quantities of free fatty acids, diglyceridesand polar lipids. The two glycolipids, monogalactosyl and digalactosyldiglycerides, formed the bulk of the polar lipids with smallamounts of phosphatidyl choline and phosphatidyl inositol. In general, the fatty acid pattern of the haustorium was intermediatebetween that of the palm kernel oil and the palm fruit mesocarp,and resembled to a great extent the fatty acids of the kerneltesta. It is suggested, from the presence of the biological membranelipids and lipolytic enzymes, that the main function of thehaustorium is that of food mobilization and transport for theyoung plant.     

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     

Cell Separation and Anatomy of Abscission in the Oil Palm, Elaeis guineensis Jacq.

Shedding of the fruit of the oil palm takes place in two co-ordinatedstages. The first, a cell separation event at a pre-defined,positionally differentiated abscission zone at the base of thefruit, is followed by further cell separation in peripheraltissue at the junction with the rudimentary androecial ringand the tepals. The position of the second separation is determinedby the age and ripeness of the fruit and the degree of pressureto which it is subjected; it is also dependent upon completionof the first stage. Implications of this unusual two stage separationprocess are discussed. Key words: Abscission, cell separation, anatomy, oil palm, Elaeis guineensis