Amount Of Pollen Grains Research Articles

Palynological and physicochemical properties of multifloral honey produced in some regions of Algeria

This study aimed to determine the palynological and physicochemical properties of multifloral honey collected from different regions of Algeria. A total of 24 different honey samples have been analysed for various physicochemical parameters (moisture, electrical conductivity, pH, acidity (free, lactone and total), Hydroxymethylfurfural (HMF), proteins, color, total sugars, fructose, glucose, sucrose, and fructose/glucose ratio). The results obtained in the present study show the variability of the chemical composition of the honey samples. The results of the study indicated that most of the honey samples were of good quality, and were found to meet all major international honey specifications. From the palynological point of view, 62.5% of the samples had a moderate amount of pollen grains per 10 gram of honey (class II); seven samples (29.16%) were rich in pollen (class III), and only two samples (8.33%) had a low pollen concentration (class I). A total of 94 pollen types, belonging to 48 botanical families, were identified. The pollen types identified per sample vary from 15 to 37, with an average of 27 types. The best represented families were Fabaceae, Boraginaceae, and Asteraceae, which present in all the samples. The best represented secondary pollen types were Echium sp., Trifolium sp., Peganum harmala, Eucalyptus sp., Olea europaea, Chenopodium sp., Ononis natrix, and Ziziphus lotus. The qualitative pollen analysis demonstrated the important participation of nectarless plants in the makeup of the honeys, especially Chenopodium sp., and Olea europaea.

The late flowering of invasive species contributes to the increase of Artemisia allergenic pollen in autumn: an analysis of 25\xa0years of aerobiological data (1995\u20132019) in Trentino-Alto Adige (Northern Italy)

Artemisia pollen is an important aeroallergen in late summer, especially in central and eastern Europe where distinct anemophilous Artemisia spp. produce high amounts of pollen grains. The study aims at: (i) analyzing the temporal pattern of and changes in the Artemisia spp. pollen season; (ii) identifying the Artemisia species responsible for the local airborne pollen load.Daily pollen concentration of Artemisia spp. was analyzed at two sites (BZ and SM) in Trentino-Alto Adige, North Italy, from 1995 to 2019.The analysis of airborne Artemisia pollen concentrations evidences the presence of a bimodal curve, with two peaks, in August and September, respectively. The magnitude of peak concentrations varies across the studied time span for both sites: the maximum concentration at the September peak increases significantly for both the BZ (p < 0.05) and SM (p < 0.001) site. The first peak in the pollen calendar is attributable to native Artemisia species, with A. vulgaris as the most abundant; the second peak is mostly represented by the invasive species A. annua and A. verlotiorum (in constant proportion along the years), which are causing a considerable increase in pollen concentration in the late pollen season in recent years.. The spread of these species can affect human health, increasing the length and severity of allergenic pollen exposure in autumn, as well as plant biodiversity in both natural and cultivated areas, with negative impacts on, e.g., Natura 2000 protected sites and crops.

Pollen spectrum of honey of Apis mellifera L. and stingless bees (Hymenoptera: Apidae) from the semi-arid region of Bahia State, Brazil

Pollen in honey reflects its botanical origin and melissopalynology is used to identify origin, type, and quantities of pollen grains of the botanical species visited by bees. This study aimed to identify the pollen spectrum of honeys from Apis mellifera and stingless bees produced in the semi-arid region of Bahia, Brazil. We analysed 78 honey samples, which were submitted to the acetolysis process for identification and quantification of pollen types. Fabaceae, Asteraceae and Euphorbiaceae were the most predominant families in pollen types. For Fabaceae, the most representative pollen types were Chamaecrista 1, Mimosa caesalpiniifolia, Mimosa pudica, Mimosa tenuiflora, Prosopis and Senna. The results indicate that the flora explored by the bees to collect nectar is diverse in the semi-arid region of Bahia and the honeys analysed were classified as multifloral.

Pollen content in a II century BC remedy from the Pozzino shipwreck (Tuscany, Italy): its sources and association with the ingredients

Six tablets, probably an ancient collyrium, were discovered in a tin pyxis recovered during the archaeological excavation of the so-called Pozzino shipwreck found in the Baratti gulf, near Piombino (Tuscany, Italy). The tablets were previously studied from a historical point of view; micro-morphological and chemical analyses were then performed to establish their composition. In addition, the tablets were subjected to pollen investigation, which revealed the occurrence of a significant amount of pollen grains. The list of pollen morphotypes is long and suggests multiple sources for the grains. Many of the morphotypes belong to Olea; many others belong to plants which display showy flowers and are commonly visited by bees, confirming the presence of a bee product already detected by the chemical analysis. The present paper focuses on the analysis of the pollen content of the medicine and offers conclusions resulting from its study. We hypothesize that the olive pollen grains were added to the tablets together with one or more ingredients, such as pollen bread and/or oleum acerbum (an oil obtained by pressing unripened drupes and which was used in antiquity for therapeutic applications).

Structure and development of anthers and connective glands in two species of Stigmaphyllon (Malpighiaceae): are heteromorphic anthers related to division of labour?

Heteranthery has been largely associated with a division of labour between anthers. Most species of Stigmaphyllon (Malpighiaceae) present heteromorphic anthers and glandular connectives of different development; yet, the functional meaning of this condition has never been explored in the genus. The aims of this study were to provide a comparative description of the structure and development of anthers and their connective glands in S. bonariense and S. jatrophifolium and to assess the existence of division of functions. Natural populations were selected to collect flowers at different stages. Anthers were subjected to morpho-anatomical, histochemical and pollen viability studies. For both species, abundance of pollen grains and size of anther and their connective glands were estimated. Three types of stamens are recognized: stamen with small, intermediate and large anthers. Anthers of both species exhibit a similar glandular tissue in the connective, and the histochemical analysis revealed that it produce a mucilagous secretion. The pattern of anther wall development, stainability and release of pollen grains was identical among anther types. For both species, we observed a positive relationship between anther size and abundance of pollen grains, but an inverse relationship between area of anthers and size (area and thickness) of connective glands in small anthers vs. intermediate and large ones. Our results evidence a specialization of anthers related to division of labour between heteromorphic stamens in two species of Stigmaphyllon. Thus, one set of anthers produces large amount of pollen grains for pollination and another sets large quantities of mucilage, which would improve pollen transport (better adherence to pollinator body and dampness maintenance). Nevertheless, heteranthery in both Stigmaphyllon species would represent a transitional state towards the division of labour rather than a stable state.

Experimental quantification of pollen with DNA metabarcoding using ITS1 and trnL

Although the use of metabarcoding to identify taxa in DNA mixtures is widely approved, its reliability in quantifying taxon abundance is still the subject of debate. In this study we investigated the relationships between the amount of pollen grains in mock solutions and the abundance of high-throughput sequence reads and how the relationship was affected by the pollen counting methodology, the number of PCR cycles, the type of markers and plant species whose pollen grains have different characteristics. We found a significant positive relationship between the number of DNA sequences and the number of pollen grains in the mock solutions. However, better relationships were obtained with light microscopy as a pollen grain counting method compared with flow cytometry, with the chloroplastic trnL marker compared with ribosomal ITS1 and with 30 when compared with 25 or 35 PCR cycles. We provide a list of recommendations to improve pollen quantification.

Cupressaceae pollen: new data about diffusion, record and preservation

Cupressaceae is one of the most widespread families in the Mediterranean region, widely used as ornamental trees both in cities and extra urban areas. The family is also known to produce a considerable amount of pollen grains. Nevertheless, Cupressaceae pollen is generally scarce in sediments and it is attested to be one of the most underrepresented pollen in ancient spectra. Cupressaceae pollen diffusion was detected by means of two sampling methods: moss cushions, which are able to accumulate pollen grains for several successive years, and volumetric sampler, which records the airborne pollen day by day. The study was conducted in the city of Florence (Italy), repeating moss samplings at the same sites for three times. The comparison between the two sampling methods revealed the low preservation of this pollen type and suggested that even low quantities of this pollen may indicate the local presence of the source plants. In order to test the contribution of the local pollen sources to the background of the airborne pollen, the pollen content of moss cushions was also related to the number of Cupressaceae plants surroundings each sampling site. The results indicate a noticeable influence of the plants growing in a short-range distance.

MiR156b from Soybean CMS Line Modulates Floral Organ Development

The miR156 and plant specific transcription factor SQUAMOSA PROMOTER BINDING PROTEIN-LIKE (SPL) are known for their function regulating plant growth and development. In this study, we identified 20 GmSPLs which are targeted by gma-miR156b via plant small RNA target and degradome analysis. And we found high transcript levels of gma-miR156b and its targeted GmSPLs in the flower of soybean cytoplasmic male sterility (CMS) line and its maintainer. The gma-miR156b direct cleavage of GmSPL2b and GmSPL9b, and have opposite expression levels during early flower buds development. We observed a high expression level of GUS protein in the anthers of the line with pgma-MIR156b::GUS reporter. Over-expression of the gma-miR156b precursor in Arabidopsis inhibited floral organ development, including reduced anther size and the amount of pollen grains per anther etc. Like miR156-targeted SPL genes, non-targeted GmSPL8s were also down-regulated in early flower bud development of soybean CMS line compared with its maintainer line, which might act in concert with miR156-targeted SPL genes to participate in the floral organ development. Quantitative real time PCR (qRT-PCR) suggested that miR156/SPL modulates floral organ development by regulating the expression of LATERAL ORGAN BOUNDARIES DOMAIN22 (LBD22), LBD36, AGAMOUS-LIKE30 (AGL30) and AGL104. Our findings will facilitate understanding of the biological functions of miR156/SPL in floral organ development of soybean CMS.

Aspectos fitotécnicos do cultivo da oliveira no Rio Grande do Sul I: biologia reprodutiva

A oliveira (Olea europaea L.), apesar de apresentar flores hermafroditas e estaminadas, possui mecanismos que favorecem a alogamia, sendo desaconselhável a formação de pomares monovarietais. A polinização da oliveira é anemófila, produzindo grande quantidade de grãos de pólen espalhados no ar durante a floração. A viabilidade econômica da produção de azeite de oliva depende da produção de frutos e vários fatores podem afetar a frutificação. Esse estudo teve como objetivo entender as relações da biologia reprodutiva com a produção de frutos em oliveira, nas condições do sul do Brazil. O estudo foi realizado em 2016 e 2017, em olival comercial localizado em Barra do Ribeiro/RS, em espaçamento de 5x7, com as cultivares Koroneiki, Arbequina e Arbosana. Analisou-se o número de inflorescências por ramo, o número de flores por inflorescência, o número de flores hermafroditas, a qualidade do pólen e o sistema de polinização. ‘Arbosana’ apresentou o maior número de flores/inflorescência. ‘Arbequina’ apresentou o maior percentual de flores hermafroditas que ‘Koroneiki’ nos dois anos avaliados, não diferindo de ‘Arbosana’ em 2017. Houve redução do percentual de flores hermafroditas para as cultivares Koroneiki e Arbequina, no segundo ano avaliado. Houve redução na viabilidade do pólen em 2017, mais expressivo em ‘Koroneiki’. Independente da cultivar, a polinização livre proporcionou maior frutificação. ‘Koroneiki’ fixou mais frutos que ‘Arbequina’; os parâmetros avaliados não foram determinantes para a frutificação das cultivares estudadas.

Rare occurrence of airborne bioparticles in a speleotherapy site: the case study of the Sant’Aloisio disused siderite mine (Brescia, Italy)

Caves and mines have a suitable microclimate in terms of temperature, humidity and air purity that could be exploited for speleotherapy. The aim of this study was to evaluate the current load of allergenic airborne bioparticles of a subterranean environment being considered as a potential site for treating respiratory allergies. Sampling was performed over 12 months (2015–2016) inside and outside the Sant'Aloisio mine by: (i) continuous aerobiological sampling with Hirst-type samplers and (ii) monthly air sampling with an on-plate volumetric sampler using three different selective culture media. The following protocols were applied for the two methodologies: (i) Samples were processed following the European standard (UNI CEN/TS 16868:2015) and analyzed by light microscopy to identify and count pollen grains and fungal spores; (ii) plates were incubated, colony-forming units (CFU) were counted and concentration of CFU was calculated. Spore and pollen load, as evaluated by the continuous monitoring, resulted in very low values inside the mine, with a total of 106 pollen grains and 41 fungal spores from two species (Alternaria and Cladosporium) collected over the entire year; the pollen and spore concentration in the subterranean environment was negligible when compared to the open-air sampling (0.2% for pollen; 0.02% for spores). Viable airborne microorganisms were less represented in the mine than in the open air (median: 7 and 83 CFU*m−3, respectively). The indoor air of the disused mine was confirmed to be suitable for hosting respiratory disease sufferers from an aerobiological point of view. The residual low quantity of pollen grains could be the result of unintentional human transport. The indoor fungal component of the viable airborne microorganisms was mostly derived from non-allergenic wood-decaying fungi.

Pollination and fruit formation in tomato culture in protected ground

Relevance The structure of the flowers of tomatoes is very thin adapted to self-pollination, and any violations of the technology of cultivation in protected ground lead to a significant reduction in the ability of plants to pollinate and fruit set. Violation of growing conditions can lead to changes in the structure of the inflorescences and flowers, which negatively affects pollination and fruit formation, reducing the yield. The article presents a review of literature data and the author’s own research on this topic. It has been established that growing conditions in cultivation structures have a greater effect on the amount of pollen produced in tomato flowers and to a lesser extent, on its quality. In the flowers of the first inflorescence, the least amount of pollen is produced. This is due to the fact that the formation of this inflorescence occurs in the seedling period, while it is experiencing more stress. Basal (the first in the inflorescence) flowers produce low-quality pollen, while its amount is maximum. Additional pollination improves fruit set by increasing the amount of pollen grains falling on the stigma of the pistil. The use of bumblebees for additional pollination increases the yield by increasing the number of ensuing fruits. The formation of polynomial flowers on tomato plants – varietal reaction. More often they are found in multi-chamber largefruited tomato hybrids. Less commonly, polynomial flowers are found in tomato hybrids with plum and pepper fruits, such flowers are not found in cherry tomato hybrids. A polynomial flower - most often the first in the inflorescence. They are formed mainly in the first 4-5 inflorescences and give accreted non-harvest fruits. In order to increase the yield and quality of fruits, polynomials need to be removed in a timely manner.

From field to food II – will pesticide-contaminated pollen diet lead to a contamination of worker jelly?

Residues of pesticides have been found in bee collected pollen and stored beebread. Pollen is the protein source for bees and hence important for nurse bees to produce larval food. However, the fate of pesticides in the pollen used for larval food production is not clarified. We conducted a feeding experiment with free-flying mini-hives of the honey bee, Apis mellifera. A mixture of 13 different substances in high concentrations (156 - 9,021 µg/kg) was offered inside the hive. During the time of feeding, worker larvae of known age were reared. At larval age three to six days, worker jelly (WJ) was harvested and subjected to a multi-pesticide residue analysis. Concentrations of the detected pesticides in the WJ increased with larval age and ranged from 2.9 - 871 µg/kg for three- to six-day-old larvae, depending on the pesticide. The amount of pesticides significantly correlates with the amount of pollen grains in the worker jelly with increasing larval age from 41 - 4,654 pollen/mg WJ. Thus, we hypothesize the addition of pollen to the WJ to be responsible for the pesticide residues in the WJ. For the first time, this study shows the real pesticide exposure of honey bee larvae to pesticides by larval food. Our results should help to better evaluate the concentrations found in the field and to conduct field realistic feeding experiments, which may be used for risk assessments or pesticide approval.

Studies on the Improvement of Date Palm Productivity Using Different Methods of Pollination and Fruit Thinning Levels

Pollination and thinning are basic procedures of date palms in terms of their impact on fruit development, quality and yield, as well as the organization yearly tree bearing. The development of pollination technology, which leads to an acceptable level of fruit set with the use of small amount of pollen grains and without a further need for thinning, is necessary to improve the productivity of date palms, especially under arid conditions. This examination was done on Saidy date palm for both progressive seasons 2017 and 2018 at El-Kharga Oasis, New Valley Governorate, Egypt. The impact of pollen grain suspension at 0.5, 1.0 and 1.5 g blended with starch 5.0 g, dust pollen at 10, 12.5 and 16.7% as well as fruit thinning at 10, 20 and 30% on fruit retained, fruit weight/bunch, yield and fruit quality were examined. The outcomes announced that utilization pollen grains suspension at 1.0 g + 5.0 g starch and dusting at 10% as well as the fruit thinning at 30% had a decrement level of fruit weight/bunch about 9.64, 9.99 and 9.64% compared to the traditional treatment, respectively. The most elevated estimations fruit weight (11.28, 11.44 and 11.22 g) were obtained from spraying pollen grains suspension at 0.5 g + 5.0 g starch, dusting at 10% and removing 30% of fruit, which led to 20.51, 22.22 and 19.87% increment over the traditional treatment as average of the two seasons, respectively. Likewise, utilizing pollen grains suspension at 0.5 g or pollen dusting at 10% and removing 30% of fruit gave the most elevated values of TSS and sugar contents, while, utilizing the traditional pollination gave the least values. We can conclude from that pollination by either pollen grains suspension at 1.0 g or dusting at 10% should be possible to acquire an extensive yield with great quality, increase the efficiency of the pollination process and combine the two methods of pollination and fruit thinning at the same time in their effect on the productivity of date palms.

Physical immobilization of particles inspired by pollination

Biomimetic systems often exhibit striking designs well adapted to specific functions that have been inspiring the development of new technologies. Herein, we explored the remarkable ability of honey bees to catch and release large quantities of pollen grains. Hair spacing and height on bees are crucial for their ability to mechanically fix pollen grains. Inspired by this, we proposed the concept of a micropatterned surface for microparticle entrapment, featuring high-aspect-ratio elastic micropillars spaced to mimic the hairy surface of bees. The hypothesis was validated by investigating the ability of polydimethylsiloxane microfabricated patches to fix microparticles. The geometrical arrangement, spacing, height, and flexibility of the fabricated micropillars, and the diameter of the microparticles, were investigated. Higher entrapment capability was found through the match between particle size and pillar spacing, being consistent with the observations that the diameter of pollen grains is similar to the spacing between hairs on bees' legs. Taller pillars permitted immobilization of higher quantities of particles, consistent with the high aspect ratio of bees' hairs. Our biomimetic surfaces were explored for their ability to fix solid microparticles for drug-release applications, using tetracycline hydrochloride as a model antibiotic. These surfaces allowed fixation of more than 20 mg/cm2 of antibiotic, about five times higher dose than commercialized patches (5.1 mg/cm2). Such bioinspired hairy surfaces could find applications in a variety of fields where dry fixation of high quantities of micrometer-sized objects are needed, including biomedicine, agriculture, biotechnology/chemical industry, and cleaning utensils.

Assessment of the potential real pollen related allergenic load on the atmosphere of Porto city

The knowledge of the allergen content in the atmosphere is a useful tool to stablish the risk allergy warnings for the sensitive people. In Portugal the main airborne allergenic pollen come from trees (such as Betula or Olea), grasses or weeds (mainly Urticaceae). The present study sought the quantification of the Bet v 1, Ole e 1, Lol p1 and Par j1–2 aeroallergen concentration as well as how weather variables influence in the pollen and allergen concentration in Porto city. Aerobiological study was carried out by a Hirst-type volumetric sampler for pollen collection and a Burkard Cyclone sampler for the aeroallergens. A regression analysis between pollen and allergens was conducted for the identification the allergenic risk days. High Pollen Allergen Potency in the atmosphere was observed considering the low levels of airborne pollen detected. A significant and positive correlation has been obtained between pollen and aeroallergen values with the temperatures whereas the correlation was negative with relative humidity, rainfall and wind speed. Back trajectory methodology was applied in order to analyse the discordances between pollen and allergen maximum concentrations. The analysis showed that when the pollen and allergen peaks were registered on the same day, air masses always comes from the continent. However, when the peaks do not coincide, the air mass comes from the continent in the case of the pollen peak and from the sea for the allergen peak. This behaviour can be a consequence of the high humidity in the air masses from the sea, which can benefit the allergen release from pollen grains. In our study it was observed that the available traditional information for allergenic Type I patients, corresponding to the amount of pollen grains in the bioaerosol, do not accurately identify the real allergenic load in the air.

Genome-wide association study for anther length in some elite bread wheat germplasm

The anther is a crucial organ for the development of the spike in bread wheat (Triticum aestivum L.). Long anthers contain large amounts of pollen grains; thus, they are favourable for cross-pollination and increase resilience against adverse environmental conditions. We conducted a genome-wide association study (GWAS) of anther length in 305 elite wheat lines evaluated during 2013–2015 in two locations and two growing seasons. The mapping panel was genotyped using a high-density Illumina iSelect 90K single nucleotide polymorphism (SNP) array. The GWAS used 18763 SNPs and identified 17 markers associated with anther length in wheat. The loci were mainly distributed across the chromosomes 3A, 3B and 7B. Further studies are required to determine if these are candidate genomic regions of anther length. In addition, anther length had high heritability, and positive correlations between anther length and grain weight per spike were observed.

The role of beetles in the pollination of the mangrove palm Nypa fruticans

The flowers of the mangrove palm Nypa fruticans attracts a diverse array of potential pollinators. However, little is known about the pollination mechanism and which functional groups are the key pollinators. Inflorescences of nine nipa palms of different flowering stages were observed three times a day between sunrise and sunset in Thailand. The apparent entomofauna activity was recorded and all inflorescences were collected for extraction and identification of the beetle fauna. Beetles extracted from female inflorescences were measured for pollen load. In addition, thermogenesis was recorded over two days on two separate inflorescences. The most frequent visitors were species of nitidulid (genus Epuraea and the subfamily Cillaeinae) and curculionid beetles. Although they only carried small amounts of pollen grains, these groups of beetles were omnipresent. Thermogenesis peaked around 6.30 am with temperature elevations reaching 6° above ambient. The result obtained in this study are compared with those of previous studies conducted elsewhere in Thailand and in the Philippinies. The combined evidence strongly suggests a pivotal role in pollination of beetle visitors to the inflorescences of Nypa fruticans.

Inheritance of fertility restoration of male-sterility conferred by cytotype Y and identification of instability of male fertility phenotypes in onion (Allium cepa L.)

ABSTRACTA novel onion (Allium cepa L.) cytoplasm, cytotype Y, was found in a previous study. Cytotype Y contained unique stoichiometry of coxI and orf725, a candidate gene responsible for male-sterility induction in onions. A S1 segregating population was produced from a single plant selected from PI273626. Although male-fertility segregated in this population, the ratio significantly deviated from single-gene inheritance. However, genotypes of RF31446 marker perfectly linked to Ms locus-controlling fertility restoration completely matched with male-fertility phenotypes, indicating that male-fertility restoration of male-sterility conferred by cytotype Y might be determined by the Ms locus. One plant derived from the S1 population showed discrepancy between male-fertility phenotype and RF31446 genotype. Although the RF31446 genotype was homozygous recessive, reduced amount of pollen grains were observed in anthers. Many pollen grains of the unstable male-sterile plant were deformed. Analysis of 13 molecular markers flanking the Ms locus showed no crossover between the Ms locus and the RF31446 marker. Ten more unstable male-sterile plants were identified from open-pollinated progenies of the unstable male-sterile plant. Viable seeds were successfully produced from unstable male-sterile plants, indicating that pollen grains of the unstable male-sterile plants were partially viable. In addition, an umbel containing unstable male-fertile flowers was identified from one of maintainer lines, although both male and female organs might be sterile in these flowers.

Trade off between quantity and size of pollen grains in the heterandrous flowers of Senna pendula (Fabaceae)

ABSTRACT Heteranthery, the presence of different types of stamens in a flower, may reduce the conflict between pollinators and plants by ensuring the resource for the pollinator without drastically affecting the availability of viable male gametes for fertilization, according to the division-of-labor hypothesis. We investigated whether the poricidal anthers of Senna pendula, a buzz-pollinated heterantherous species, present morphological and physiological differences among pollen grains from the three sets of stamens. We compared quantity, ornamentation, size and fecundity of pollen from long, medium and short stamens. The short feeding stamens produced larger but fewer pollen grains than the long pollinating stamens, which produced smaller pollen grains but in higher quantity. The total pollen volume of pollinating and feeding stamens per flower, however, was the same. The medium stamen produced less-fertile small pollen grains and seems to play no specific role in bee feeding and pollination. Our results indicate differential allocation of pollen for pollinating and feeding stamens mediated by heteranthery. The differences in volume versus quantity of pollen grains fit the division-of-labor hypothesis well for heterantherous pollen-only flowers with poricidal anthers.

Multivariate Analysis of MALDI Imaging Mass Spectrometry Data of Mixtures of Single Pollen Grains.

Mixtures of pollen grains of three different species (Corylus avellana, Alnus cordata, and Pinus sylvestris) were investigated by matrix-assisted laser desorption/ionization time-of-flight imaging mass spectrometry (MALDI-TOF imaging MS). The amount of pollen grains was reduced stepwise from > 10 to single pollen grains. For sample pretreatment, we modified a previously applied approach, where any additional extraction steps were omitted. Our results show that characteristic pollen MALDI mass spectra can be obtained from a single pollen grain, which is the prerequisite for a reliable pollen classification in practical applications. MALDI imaging of laterally resolved pollen grains provides additional information by reducing the complexity of the MS spectra of mixtures, where frequently peak discrimination is observed. Combined with multivariate statistical analyses, such as principal component analysis (PCA), our approach offers the chance for a fast and reliable identification of individual pollen grains by mass spectrometry. Graphical Abstract ᅟ.