Genetic modification of the waxy character in barley under the action of exogenous DNA of the wild variety

Genetic transformation was studied on spring barley mutants carrying the recessive mutant allele of waxy locus.Analysis of the pollen grains of 38 control plants that were not subjected to any treatment showed that in the whole sample there was no mutant grain that stained black with iodine. It is also indicative of the genotypical purity of the original waxy plants.After mechanical damage (puncture in the top and in the side of a grain) there were 5 pollen grains fo wild type among 124000 mutant grains. Injection of grains with 2 μl distilled water led to the emergence of pollen grains that stained black at a frequency similar to that after puncture. The overall frequency of wild barley pollen grains for all control variants was 2.2·10⁻⁵.The frequencies of wild-type pollen grains were practically the same after injections of DNA from E. coli, extensively deproteinized highly polymeric DNA from barley leaves or slightly deproteinized low polymeric DNA from barley endospermal material.There was no marked increase of the wild pollen frequency after the injection of slightly deproteinized low polymeric DNA from the endospernal material (2.2·10⁻⁵ in the control versus 3.7·10⁻⁵ in the experiment).The analysis of the material for the amount of altered pollen grains in invidual plants also unequivocally demonstrated significant differences between the control and the experiment. In the first four variants there was no plant having over these altered pollen grains among the 2500 mutant grains examined. In the variants with injections of barley DNA differing in the extent of deproteinization and in polymerisation only in one case (of low polymeric slightly deproteinized DNA) there were no plants with many altered pollen grains. In all the other variants there were plants having much pollen of wild type.The largest number of plants with a great many affected pollen grains occurred in the variant with highly polymeric DNA from the endospermal material not subjected to deproteinization with chloroform and isoamyl alcohol.     

A comparative study on the allergenicity, structure, and ultrastructure of two Acacia pollen grains in guinea pigs

Acacia saligna and Acacia victoria are native to Australia brought to and grown in Southern Iran. They have since had a widespread distribution and become native in Iran. As people of the region are exposed to the pollen grains from these plants during a 5 months period, this study aimed at investigating the allergenicity of their mature pollen grains. In addition, the structural and ultrastructural as well as the total protein content of the mature pollen grains were analyzed. Pollen grains of A. saligna and A. victoria were collected from the suburbs of Ahvaz, Iran. Pollen extracts (15 % concentration) were prepared in PBS (pH 7.2), and 4- to 6-week-old male guinea pigs (Hartly) were used for allergenicity tests. Skin tests showed a significant increase in flare diameter. Clinical tests also showed a significant change in the levels of eosinophils, neutrophils, and IgE. Comparative analysis of the allergenicity of A. saligna and A. victoria pollen grains revealed a higher IgE level in the latter. Comparative analysis of pollen characteristics was performed using both light and electron microscopy for sporoderm structure and ultrastructure, respectively. Twelve percent PAGE analysis of the total protein content of mature pollen grains showed a greater number of bands in A. victoria, while four bands were common in both species. In conclusion, this study demonstrates that both A. saligna and A. victoria pollen grains are allergenic, with a greater allergenicity of A. victoria pollen grains. In addition, the structural and ultrastructural as well as the total protein content of the mature pollen grains are revealed, and a potential protein allergen is proposed.     

A transient accumulation of poly(A)-containing RNA in the tapetum of Hyoscyamus niger during microsporogenesis

The distribution of poly(A)-containing RNA in the tapetal cells of Hyoscyamus niger during microsporogenesis was followed by in situ hybridization with [³H]poly(U) as a probe. Although no poly(A)-containing RNA accumulated in the premeiotic tapetum, [³H]poly(U) binding sites were detected in the tapetum as meiosis was completed in the microsporocytes. Accumulation of poly(A)-containing RNA in the tapetal cells reached a peak before the first haploid mitosis in the pollen grains. With the onset of tapetal senescence at the late uninucleate stage of the pollen grain, [³H]poly(U) binding sites gradually decreased and they completely disappeared in the tapetum at the binucleate pollen stage. The significance of the results is discussed, particularly with regard to the possible role of tapetum in the synthesis of informational macromolecules during microsporogenesis.     

Consumption of Bt Rice Pollen Containing Cry1C or Cry2A Protein Poses a Low to Negligible Risk to the Silkworm Bombyx mori (Lepidoptera: Bombyxidae)

By consuming mulberry leaves covered with pollen from nearby genetically engineered, insect-resistant rice lines producing Cry proteins derived from Bacillus thuringiensis (Bt), larvae of the domestic silkworm, Bombyx mori (Linnaeus) (Lepidoptera: Bombyxidae), could be exposed to insecticidal proteins. Laboratory experiments were conducted to assess the potential effects of Cry1C- or Cry2A-producing transgenic rice (T1C-19, T2A-1) pollen on B. mori fitness. In a short-term assay, B. mori larvae were fed mulberry leaves covered with different densities of pollen from Bt rice lines or their corresponding near isoline (control) for the first 3 d and then were fed mulberry leaves without pollen. No effect was detected on any life table parameter, even at 1800 pollen grains/cm² leaf, which is much higher than the mean natural density of rice pollen on leaves of mulberry trees near paddy fields. In a long-term assay, the larvae were fed Bt and control pollen in the same way but for their entire larval stage (approximately 27 d). Bt pollen densities ≥150 grains/cm² leaf reduced 14-d larval weight, increased larval development time, and reduced adult eclosion rate. ELISA analyses showed that 72.6% of the Cry protein was still detected in the pollen grains excreted with the feces. The low exposure of silkworm larvae to Cry proteins when feeding Bt rice pollen may be the explanation for the relatively low toxicity detected in the current study. Although the results demonstrate that B. mori larvae are sensitive to Cry1C and Cry2A proteins, the exposure levels that harmed the larvae in the current study are far greater than natural exposure levels. We therefore conclude that consumption of Bt rice pollen will pose a low to negligible risk to B. mori.     

Indoor and outdoor pollen concentrations in private and public spaces during the <Emphasis Type="Italic">Betula</Emphasis> pollen season

Although the number of studies of pollen concentrations inside and outside buildings is increasing, little is known about the efficiency of penetration of pollen from outdoor to indoor air, and further. We studied indoor and outdoor pollen concentrations in the town of Lappeenranta and in the municipality of Rautjärvi in SE Finland from May 3–23, 2004, i.e. throughout the Betula pollen season, and assessed the risk of exposure to pollen grains. Pollen concentrations were measured inside and outside a block of flats, a detached house, and the regional central hospital, using rotorod-type samplers; in the town of Joutseno data were compared with Burkard counts. Outdoor concentrations of Betula pollen grains ranged between low and abundant (0–855 grains m^?3). The corresponding indoor concentrations near the main front doors varied from low to moderate (0–17 grains m^?3) in the central hospital and were low (<10 grains m^?3) in both residential buildings. Indoor concentrations further from the main front door were low (<10 grains m^?3) at all study sites. The concentrations of Betula pollen decreased substantially from outdoors to indoors, and further toward the centre of the building, probably indicating relatively poor penetrating properties of the pollen grains and/or the short-lived presence of pollen grains in indoor air. The concentrations of Betula pollen inside the buildings during the peak flowering period were mostly at a level barely inducing reactions even in the most sensitive persons.     

RADIOAUTOGRAPHIC LOCALIZATION OF DEOXYTHYMIDINE TRIPHOSPHATE IN TRADESCANTIA POLLEN GRAINS DURING DNA SYNTHESIS

Tradescantia pollen grains, isolated during the period of DNA synthesis in the generative cell, accumulate deoxythymidine triphosphate (dTTP)-³H after incubation with thymidine-³H in the presence of millimolar deoxyadenosine. Most of this dTTP-³H was found to resist extraction by the fixative, cold ethanol-acetic acid, and its location was investigated by radioautography with thin, dry emulsion. Substantial binding of dTTP-³H occurred as an artifact; but when nuclei were isolated from the fixed pollen grains by sonication, it was found that they were differentially labeled: generative nuclei contained dTTP-³H, vegetative nuclei did not. This observation is discussed and is interpreted as evidence supporting the idea that thymidine is phosphorylated only in the generative cell of the pollen grain.     

Palynofloras from the upper Barremian-Aptian Nishihiro Formation (Outer Zone of southwest Japan) and the appearance of angiosperms in Japan

Palynomorphs are reported for the first time from the Nishihiro Formation (Wakayama Prefecture, Outer Zone of southwest Japan). The Nishihiro Formation consists of brackish to shallow marine deposits, dated as late Barremian to Aptian from geological correlations. Spores prevail in the assemblage, representing Filicopsida (mainly Cyatheaceae and Anemiaceae), Marchantiopsida and Lycopsida. The pollen assemblage is dominated by Coniferales, whereas Gnetales and Bennettitales/Cycadales are only rarely observed. Moreover, we report angiosperm pollen grains of the genus Retimonocolpites for the first time in the Early Cretaceous sediments of Japan. Pollen grains of the Retimonocolpites Group are typical of early angiosperms and commonly found in assemblages from the early to mid-Cretaceous of all paleofloristic provinces. Until this paper, the oldest angiosperm fossils in Japan were represented by a single seed and a wood reported from the Albian of Hokkaido. The oldest reliable angiosperm pollen grains were reported in Hokkaido from the Cenomanian, and in Honshu from the Coniacian. Thus, Retimonocolpites pollen grains reported in the present study represent the oldest record of angiosperms in Japan. They indicate an appearance of the angiosperms in Japan older than thought until now, which is consistent with that proposed elsewhere in eastern Asia.     

Air pollen dispersal in a tropical area

Volumetric data on airborne pollen have been gathered for two consecutive years at a neotropical location (Caracas). Among the 65 taxa which were identified, pollen from aCupressus species (introduced) and from aCecropia species (indigenous) were dominant. Less numerous but also abundant (daily averages ≥5 grains/m³ air) were pollen from Gramineae, Urticaceae,Alcalypha, Pinus, Piperaceae andMimosa. Pollen grains were recorded daily throughout the year. They increased in numbers during April–May and again during November–December. The first peak was contributed mainly by indigenous species, the second peak mainly by introduced species.     

Systematic importance of pollen morphological features of selected species from the genus Rosa (Rosaceae)

The aim of this study is verification of the taxonomic usefulness of the pollen grain features studied, based on pollen morphology of 32 wild species from all 4 subgenera and all 10 sections of the genus Rosa, mainly for delimitation of subgenera, sections, and species. The measurements and observations were carried out with both light microscopy and scanning electron microscopy. Only correctly formed pollen grains (30 per specimen) were measured, and 960 pollen grains were examined in total. They were analyzed for 14 quantitative features of pollen grains and exine sculpturing and the following qualitative ones: outline, shape, and operculum structure. Our study revealed that the diagnostic features of pollen grains studied were: exine sculpture, length of polar axis, and pollen shape (P/E ratio). On the basis of the above characters, five species were isolated and the remaining ones were included in several groups isolated on the basis of exine sculpture types. The following three exine sculpture types occurred in the species studied: granular-verrucate (in R.?stellata), striate-psilate (in R.?multibracteata and R.?multiflora), and striate (the remaining species). R.?banksiae is characterized by small pollen grains, while R.?setigera has strongly elongated pollen with P/E ratio >1.5. Exine sculpture features considered to be diagnostic should be treated as auxiliary because they fail to differentiate individual species, although they can be helpful in distinguishing groups of species of similar exine sculpture. The arrangement of the species examined on a dendrogram only slightly corroborates division of the Rosa genus into subgenera and sections currently adopted in taxonomy (Rehder 1940). An interesting result was reported for the species studied from the Caninae (R.?agrestis, R.?canina, R.?dumalis, R.?jundzillii, and R.?rubiginosa) section which, despite hybrid nature, with the exception of R.?villosa, grouped in the same, most separated group of species.     

Pollen transport by clothes

Pollen transport into houses via clothing was studied on different types of fabrics after clothing was aired or worn outdoors. After walking through grassland, 68 pollen grains/cm² were found on clothes (tape samples). The amount of grass pollen, and especially pollen from insect-pollinated plants, increased from the shirt towards the shoes. The amount of pollen on clothes aired outdoors in a yard depended on the concentration in the ambient air and the texture of the fabrics. On vacuumed samples, 1.2 grains/cm²/h adhered to the furry fabric of fleece and wool, whereas only 0.3 grains/cm²/h adhered to a tight weave polyamide coat and a denim jacket. A moist cotton shirt gave slightly higher pollen counts in both the tape (8.6 grains/cm²/h) and the vacuumed samples (1.0 grains/cm²/h) compared to a dry shirt (5.6 and 0.6 grains/cm²/h), but the difference was not significant. Tape samples gave tenfold higher pollen numbers compared to vacuumed samples, probably due to the more optimal location of the tape sampling area on top of the shoulders. We conclude that clothing constitutes an important route for carrying allergenic pollen into houses. Pollen transport can be decreased by shaking outdoor clothing before entering a residence. In our case, shaking removed 68% pollen grains from trousers.     

Arabidopsis mutant of AtABCG26, an ABC transporter gene, is defective in pollen maturation

In plants, pollen is the male gametophyte that is generated from microspores, which are haploid cells produced after meiosis of diploid pollen mother cells in floral anthers. In normal maturation, microspores interact with the tapetum, which consists of one layer of metabolically active cells enclosing the locule in anthers. The tapetum plays several important roles in the maturation of microspores. ATP-binding cassette (ABC) transporters are a highly conserved protein super-family that uses the energy released in ATP hydrolysis to transport substrates. The ABC transporter gene family is more diverse in plants than in animals. Previously, we reported that an Arabidopsis half-size type ABC transporter gene, COF1/AtWBC11/AtABCG11, is involved in lipid transport for the construction of cuticle layers and pollen coats in normal organ formation, as compared to CER5/AtWBC12/AtABCG12. However, physiological functions of most other ABCG members are unknown. Here, we identified another family gene, AtABCG26, which is required for pollen development in Arabidopsis. An AtABCG26 mutant developed very few pollen grains, resulting in a male-sterile phenotype. By investigating microspore and pollen development in this mutant, we observed that there was a slight abnormality in tetrad morphology prior to the formation of haploid microspores. At a later stage, we could not detect exine deposition on the microspore surface. During pollen maturation, many grains in the mutant anthers got aborted, and surviving grains were found to be defective in mitosis. Transmission of the mutant allele through male gametophytes appeared to be normal in genetic transmission analysis, supporting the view that the pollen function was disturbed by sporophytic defects in the AtABCG26 mutant. AtABCG26 can be expected to be involved in the transport of substrates such as sporopollenin monomers from tapetum to microspores, which both are plant-specific structures critical to pollen development.     

Fluorescence from abnormally sterile pollen of the Japanese apricot

We observed trees of the Japanese apricot, Prunus mume ‘Nanko’ (Rosaceae), bearing two types of flowers: 34% had blue fluorescent pollen under UV irradiation, and 66% had non-fluorescent pollen. The fluorescent pollen grains were abnormally crushed, sterile, and devoid of intine and pollenkitt. The development of microspores within anthers was investigated: in the abnormally developed anthers, tapetal cells were vacuolated at the unicellular microspore stage, and fluorescent pollen was produced. Compounds responsible for the blue fluorescence of pollen were identified as chlorogenic acid and 1-O-feruloyl-β-D-glucose. The anthers with fluorescent pollen contained 6.7-fold higher and 3.8-fold lower amounts of chlorogenic acid and N¹,N⁵,N¹⁰-tri-p-coumaroylspermidine, respectively, compared to those with non-fluorescent pollen. The tapetal vacuolization, highly accumulated chlorogenic acid, and deficiency of N¹,N⁵,N¹⁰-tri-p-coumaroylspermidine imply that low-temperature stress during the early unicellular microspore stage caused a failure in microsporogenesis. Furthermore, potential effects of the visual difference on the bee behavior were also discussed through the colorimetry. The sterility, likely induced by low-temperature stress, and the preference of honeybees for fluorescence may reduce the pollination efficiency of P. mume.     

Influence of adult diet on the fecundity and survival of the predator,Chrysopa scelestes [Neur.: Chrysopidae]

Studies were conducted in the laboratory to determine the most suitable diet for adults ofChrysopa scelestes Banks that would result in the maximum fecundity and longevity, without adversely affecting hatchability. Out of 6 adult diets tested, the died containing 40% honey and pollen grains of castor,Ricinus communis L. has influenced upon the female for production of more eggs. On an average, 796 eggs were laid in 36.83 reproductive days, this was followed by Protinex^? + fructose + pollen grains and honeydew of mealy bug,Planococcus citri (Risso) + pollen grains. The diet consisting of 40 % honey had little effect either on the per day reproduction or on the effective ovipositional period for total number of egg production. Pre-ovipositional period was observed to be extended in 40% honey followed by honeydew ofP. citri + pollen grains. Hatching of larvae was found to be not affected by various diets.

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Résumé Des études de laboratoire ont été menées dans le but de mettre au point un régime pourChrysopa scelestes Banks assurant une fécondité et une longévité maximales et n'affectant pas l'éclosion des jeunes larves. Parmi les 6 régimes essayés, celui qui contient 40 % de miel et du pollen de ricinRicinus communis L. a donné lieu à la ponte la plus abondante de la part des femelles. En moyenne, chaque femelle dépose alors 796 œufs en 36,8 j de ponte. Viennent ensuite les régimes constitués de Protinex^￡, fructose et pollen, puis du miellat de la cochenille farineusePlanococcus citri (Risso) et de pollen. La nourriture à base de 40% de miel aboutit à une fécondité totale très réduite, tant par une incidence sur la fécondité quotidienne que sur la durée de la ponte. La durée de la période de pré-oviposition subit l'allongement le plus considérable dans le cas de l'alimentation avec 40% de miel, suivi par celui que provoque le miellat deP. citri additionné de pollen. L'éclosion des jeunes larves n'a pas été influencée par les divers régimes imaginaux testés.

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Contribution No. 350/83 of I.I.H.R., Bangalore-89.     

A neotaphonomic experiment in pollen oxidation and its implications for archaeopalynology

Oxidation is considered to be a major taphonomic process involved in differential pollen preservation. An experimental protocol has been developed in the laboratory to test the impact of oxidation on pollen concentrations. Seven modern pollen taxa were selected among common trees, shrubs and herbaceous plants from the European flora, with regard to their typical pollen morphology (Pinus, Alnus, deciduous Quercus, Cichorioideae, Caryophyllaceae, Ericaceae and Poaceae). An aqueous solution of potassium permanganate (KMnO₄) was used to oxidise the pollen grains. The impact of oxidation was measured as a function of increasing oxidation intensity and increasing exposure time. For each taxon, the pollen concentration (grains µl⁻¹) was measured following each oxidation stage. The results show that all pollen taxa are affected by oxidation. Both low oxidant concentrations and short oxidation exposure times led to a fast decrease in pollen concentrations. The thickness of the exine and a specific morphology appear to be the deciding factors controlling the ability to withstand oxidation. A simulation of the impact of oxidation was performed on two model pollen spectra simulating a forested and an open environment. Significant differences were recorded between the initial and final pollen rates. The AP/NAP ratio is modified to a greater extent in the spectrum associated with the open environment. However, over-representation of a specific taxon in a pollen spectrum cannot be attributed to the impact of oxidation alone. For instance, when Cichorioideae are recorded with high frequencies in pollen analyses carried out in an archaeological context, oxidation should not be regarded as the only taphonomic process responsible for this over-representation. The differential conservation of pollen is a complex process in which oxidation represents but one of a variety of interacting taphonomic factors (such as pollen transport, bacterial activity, temperature, pH, hygrometry).     

AN AUTORADIOGRAPHIC STUDY OF RNA SYNTHESIS DURING POLLEN EMBRYOGENESIS IN HYOSCYAMUS NIGER (HENBANE)

RNA synthesis during pollen embryogenesis in cultured anther segments of Hyoscyamus niger (henbane) has been followed by autoradiography of ³H-uridine incorporation. Embryogenic divisions were initiated in binucleate pollen grains in which the generative nucleus or both generative and vegetative nuclei synthesized RNA. When the first haploid mitosis in culture resulted in pollen grains with two nearly identical nuclei, those in which both nuclei synthesized RNA became embryogenic. Binucleate pollen grains in which ³H-uridine incorporation was confined exclusively to the vegetative nucleus gradually became starch-filled and nonembryogenic. Based on the degree of involvement of the vegetative nucleus in embryoid formation, some differences were noted between the counts of autoradiographic silver grains over cells cut off by the generative and vegetative nuclei during progressive embryogenesis. The possible significance of RNA synthesis in the nuclei of binucleate pollen grains in determining the pathway of embryogenic divisions is discussed.     

Effects of exogenous phytohormones on intracellular pH of Petunia hybrida pollen grains

The effects of exogenous phytohormones (IAA, ABA, and GA₃) on the intracellular (cytoplasmic) pH (pH_c) in ungerminating and germinating petunia (Petunia hybrida L.) pollen grains were studied. The pH_c values were measured with fluorescein diacetate. In ungerminating pollen grains, all phytohormones reduced pH_c relatively rapidly; after 10–15 min, initial value was restored. In germinating pollen grains, IAA and ABA induced a relatively rapid cytosol alkalization, which was not reversed during experiment. GA₃ acidified the cytosol, i.e., exerted the effect similar to that in ungerminating pollen grains. Sodium orthovanadate suppressed completely the hormone-induced pH_c shift toward alkaline values in germinating pollen grains, whereas this inhibitor did not affect pH_c in the absence of phytohormones. Sodium orthovanadate also slowed the recovery of pH_c after hormone-induced cytoplasm acidification in ungerminating pollen grains, reduced pH_c in control ungerminating grains, and weakened substantially the effects of all phytohormones on these pollen grains. On the basis of these results, we suggested that physiological activities of phytohormones in this system were mediated by pH_c modulation, namely, a transient disturbance in the cytosolic pH homeostasis, which could trigger further phytohormone-induced cell responses. We concluded that a hormone-induced cytoplasm alkalization in pollen grains was mediated by the activity of their plasma membrane H⁺-ATPase and that this proton pump was involved in the control of pH_c in both germinating and ungerminating pollen grains.     

Vegetation reconstruction on the basis of pollen in Late Pleistocene hyena coprolites from San Teodoro Cave (Sicily, Italy)

Vegetation reconstruction based on pollen from coprolites of extinct spotted hyena (Crocuta crocuta spelaea, Goldfuss 1832) recovered from excavations carried out in 1998 at San Teodoro Cave (Sicily, Italy) supports previous indications of pre-Late Glacial conditions. Eight of the twelve coprolites analysed contained well-preserved pollen grains. There is a general similarity between the pollen contents from the coprolites but they show variability. They suggest a main vegetation type dominated by steppic taxa (Poaceae, Artemisia, Ephedra, Chenopodiaceae and Asteraceae) but also including arboreal taxa (Pinus and Cupressaceae). Low percentages of pollen of mesophilous woody taxa (Quercus, Betula, Abies, Alnus, Pistacia, among others) are noticeable, suggesting the existence of nearby refugia for temperate and Mediterranean vegetation. A reconstruction of the landscape, using the coprolite pollen record and other pollen records from Sicily and south Italy, shows the predominance, during the pre-Late Glacial, of a wooded steppe biome, with elements representing a variety of local environmental conditions.     

Molecular and physiological characterisation of a 14-3-3 protein from lily pollen grains regulating the activity of the plasma membrane H+ ATPase during pollen grain germination and tube growth

A 14-3-3 protein has been cloned and sequenced from a cDNA library constructed from mRNAs of mature pollen grains of Lilium longiflorum Thunb. Monoclonal antibodies (MUP 5 or MUP 15) highly specific against 14-3-3 proteins recognised a 30-kDa protein in the cytoplasmic fraction of many various lily tissues (leaves, bulbs, stems, anther filaments, pollen grains, stigmas) and in other plants (Arabidopsis seedlings, barley recombinant 14-3-3). In addition, 14-3-3 proteins were detected in a microsomal fraction isolated from pollen grains and tubes, and the amount of membrane-bound 14-3-3 proteins as well as the amount of the plasma membrane (PM) H⁺ ATPase increased during germination of pollen grains and tube growth. No change was observed in the cytoplasmic fraction. A further increase in the amount of 14-3-3 proteins in the microsomal fraction was observed when pollen grains were incubated in germination medium containing 1 μM fusicoccin (FC) whereas the number of 14-3-3s in the cytoplasmic fraction decreased. Fusicoccin also protected membrane-bound 14-3-3 proteins from dissociation after washing with the chaotropic salt KI. Furthermore, FC stimulated the PM H⁺ ATPase activity, the germination frequency and the growth rate of pollen tubes, thus indicating that a modulation of the PM H⁺ ATPase activity by interaction with 14-3-3 proteins may regulate germination and tube growth of lily pollen. Received: 20 June 2000 / Accepted: 2 October 2000     

Analysis of airborne pollen fall in Sakarya, Turkey

In this study, pollen grains were identified using Durham sampler in the atmosphere of Sakarya in 2000 and 2001. During these two years, a total of 10 805 pollen grains were recorded. A total of 5 386 pollen grains per cm² were recorded in 2000 and a total of 5 419 pollen grains per cm² in 2001. Pollen fall in the years 2000–2001 comprised grains belonging to 40 taxa and some unidentified pollen grains. Of these taxa, 22 belonged to arboreal and 18 taxa to non arboreal plants. Total pollen grains consisted of 69.45% grains from arboreal plants, 28.11% grains from non-arboreal plants and 2.44% unidentified pollen grains. In the region investigated, Gramineae, Pinus sp., Quercus sp., Cupressaceae/Taxaceae, Salix sp., Platanus sp., Populus sp., Carpinus sp., Fagus sp., Chenopodiaceae/Amaranthaceae, Xanthium sp., Moraceae, Corylus sp., Fraxinus sp., and Urticaceae released the greatest amount of pollen. The season of maximum pollen fall was from March to May, with a prevalence of arboreal pollen in the first months, and of pollen from non-arboreal plants in the last months of the year.