Various organelles change their morphological structure and function during development as male gametophytes. The coexistence of bicellular and tricellular pollen types, a rare feature among angiosperms, positions Mitrephora tomentosa as an intriguing model for studying organelle dynamics during the final stages of pollen development. Using transmission electron microscopy (TEM), we observed the dynamic changes of ultrastructure and number in endoplasmic reticulum, plastids, vacuoles and mitochondria during M. tomentosa pollen development. Striking ultrastructural differences in these organelles, e.g. endoplasmic reticulum, plastids, vacuoles and mitochondria between binucleate and trinucleate pollens suggested that the binucleate pollen in M. tomentosa is shed in a metabolically active and highly hydrated state, representing an intermediate developmental stage during pollen maturation. Asynchrony in pollen development within the anther likely caused the coexistence of binucleate and trinucleate pollen in M. tomentosa. We propose that the year-round stable tropical climate - characterised by high temperature and humidity - provides an accommodative environment for incompletely dehydrated pollen, i.e. bicellular pollen, to undergo a second mitosis post anther dehiscence in M. tomentosa.
Pollen micromorphology relations are provided by previous research in the Ornithogaloideae subfamily. The present research focused on the sporoderm characteristics of Albuca virens (syn: Stellarioides tenuifolia), Ornithogalum arcuatum (syn: Loncomelos arcuatum) and Ornithogalum sintenisii. The pollen ultrastructure of these species was examined using transmission electron microscopy (TEM). The results indicated that the pollen wall thickness of A. virens differed from that of the other taxa in some features such as ectexine, tectum, foot layer and intine layer thickness, the ratio of tectum to foot layer thickness (T/F ratio) and the measurements of the length and width of columellae. All the studied taxa had two intine layers in the sulcus membrane. The endexine state of A. virens was similar to that of O. arcuatum. In conclusion, the sporoderm data from this study support the taxonomical position of A. virens and its close relation to Ornithogalum taxa.
Pollen morphology of ten species and three varieties of the genus Melanoseris Decne. (Cichorieae-Asteraceae) from Western Himalayas, Hindukush and Karakorum ranges was studied. Pollen were examined using light, fluorescent and scanning electron microscopy. Pollen of eight taxa were studied for the first time including four endemic species. Pollen are usually isopolar, spheroidal to oblate-spheroidal, elliptic to rarely circular in equatorial and hexagonal in polar view, trizonocolporate and echinolophate with 15 lacunae. Significant variation has been found mainly in pollen size, number of echinae and ornamentation of the polar area. Pollen ranges from 27 to 56 & micro;m in length and from 30 to 56 & micro;m in diameter. Polar area varies from small to moderately extensive with 2-15 spines. Agglomerative analysis based on 12 pollen character showed the well-defined clustering pattern, explaining total variation and separation of the studied taxa. Two distinct pollen-types: Melanoseris astorensis and Melanoseris macrorhiza were recognised. Keys to pollen-types, and species of each pollen type are provided. An attempt has been made to correlate the results of present palynological studies with that of recent taxonomic treatment and phylogenetic tree of Lactucinae. The pollen morphological data well-support the gross morphological characters at the species and infra-specific level, however, no significant difference was observed in the pollen characters at variety level. The objective of the palynomorphology of Melanoseris is to analyse and describe significant pollen characters across the genus with an aim to delineate species boundaries and also contribute to the positioning of the Melanoseris taxa in future systematic studies.
Fungal spores are important aerosols in the atmosphere, directly affecting many living groups such as plants, humans, and animals. In the present study, the diversity and concentrations of fungal spores in the atmosphere of the megacity & Scedil;anl & imath;urfa Province - a megacity with a population exceeding 2.5 million and the third largest agricultural city in T & uuml;rkiye - were determined over two consecutive years using a Hirst-type seven-day volumetric spore trap. A total of 28 genera, one family, two orders, one class, single-septate ascospores, and fungal fragments were identified. The dominant fungal spores (those representing more than 1% of the annual total) were Agrocybe, Alternaria, Aspergillus/Penicillium type, Botrytis, Cladosporium, Ganoderma, fungal fragments, Leptosphaeria, Pleospora, Pucciniales type, and Ustilaginales type. Daily concentrations of the detected fungal spores and daily meteorological data were statistically evaluated. Results indicated that dry air spores predominated, and that temperature was an important factor in increasing the concentrations of dominant fungal spores overall. Additionally, a fungal spore calendar for the study area was prepared for the first time. This study is expected to serve as a valuable resource for the prevention and treatment of allergenic disorders, as well as for the prevention and control of plant and animal diseases.
Gesnerioideae comprises herbaceous plants, shrubs, or occasionally small trees. It includes 77 genera and more than 1200 species in the New World tropics, divided into five tribes: Titanotricheae, Napeantheae, Beslerieae, Coronanthereae, and Gesnerieae. We investigated the pollen morphology of Titanotricheae (monospecific, Titanotrichum oldhamii), Beslerieae (Besleriinae, four spp.), and Coronanthereae (Coronantherinae, three spp.; Mitrariinae, three spp.) using light microscopy (LM) and scanning electron microscopy (SEM). Pollen grains were described qualitatively and quantitative data were analysed through descriptive and multivariate statistics. The pollen grains of the analysed tribes differ mainly in their size (small, small to medium, medium), type and number of apertures (3[4]-colpate or 3-colporate; endoaperture circular, lalongate or lolongate), exine thickness (very thin, thin or thick), and exine ornamentation (microverrucate, microreticulate or reticulate). The qualitative (pollen description and pollen key) and quantitative data (descriptive and multivariate analysis) allowed us to infer that there is more similarity between the pollen grains of Coronanthera (Coronantherinae, Coronanthereae) and Beslerieae. Concurrently, the monotypic genus Rhabdothamnus (Coronantherinae, Coronanthereae) is more closely related to the monotypic genera Titanotrichum (Titanotricheae), Asteranthera, Mitraria and Sarmienta (Mitrariinae, Coronanthereae). In addition, this study described the pollen morphology of seven of the 11 studied species for the first time, increasing knowledge about the group. The qualitative and quantitative pollen data contribute to a more accurate delimitation of the genera and species within the Gesnerioideae tribes.
The present study aimed to characterise the pollen morphology of 18 native species of Papilionoideae (Fabaceae), analysing and describing the qualitative and quantitative data of pollen grains of native species in remaining forest fragments of the Brazilian Cerrado biome. Using pollen morphological traits may contribute to characterising genera and species and a better understanding of biodiversity. And identify the morphological variation in the pollen grains of these species. The analyses were carried out with herbal materials, with the pollen grains being acetolysed and measured using light microscopy. Details of the exine were investigated using scanning electron microscopy. Qualitative data were described, and quantitative data were subjected to descriptive statistical analysis and multivariate analysis. The Papilionoideae taxa analysed present 3-colporate pollen grains (except Cochliasanthus caracalla). Variations in size, amb, shape, length, and width of the apertures, type of endoaperture, ornamentation, and thickness of the exine layers contribute to the distinction of species and confirm the pollen diversity of the subfamily. Details such as bridge, margo, and fastigium help identify the studied pollen. Pollen grains in 3-colporate monads, with mainly microreticulate or reticulate ornamentation, characterise the palynology of Papilionoideae; however, the pollen has diagnostic characteristics (especially regarding the apertures - bridge, margo and fastigium) that confirm the subfamily as a eurypalynous group.
Chamaecrista is the most diverse genus in the subfamily Caesalpinioideae (Leguminosae), and is one of the richest taxa in terms of species diversity in Brazil. Its monophyly is supported by phylogenetic studies, and associated polyphyletic clades have been identified. Although it is important, its palynological description is limited, and no specific studies on this taxon are available. Thus, the aim of the present study is to characterise the morphology of the pollen grains of some Chamaecrista species to expand the knowledge of the palynology of the group and provide micromorphological data for applied studies. The pollen morphology and ultrastructure of 34 taxa of Chamaecrista, with representatives of the four sections are described based on the results from light, scanning and transmission electron microscopy. The data show that there are morphological differences among the species, making it possible to distinguish them through exine ornamentation and aperture type, including bridge types. The pollen grains are monads, isopolar or apolar, medium to large, and prolate-spheroidal to prolate with a subcircular to triangular shape. There is variation in the apertural type, with 3-colporate, 3-(4)-colporate and 3-(6)-colporate pollen grains, and the 6-colporate pollen grains have a regular tetrahedral shape. The exine is characterised predominantly as perforate, microfossulate, microreticulate, and psilate. Under transmission electron microscopy, the presence of a sexine bridge joining the two edges of the ectoaperture was recorded. The presence of bridge and heteromorphism in the number of apertures and shape of pollen grains are new characteristics for the genus and are described for the first time.
Melipona mandacaia is an endemic stingless bee in the Caatinga, with significant importance for meliponiculture and the pollination of Brazilian species. Thus, identifying the flora associated with honey production contributes to ecological knowledge and meliponicultural management plans for the species. The objective of this study was to identify the pollen types present in the honey provisioned by Melipona mandacaia and characterise the flora associated with the found pollen types. Additionally, it aimed to relate the pollen diversity of honey to the climatic seasonality in an area of the Caatinga biome. Honey samples were collected over one year from six Melipona mandacaia hives located in a Caatinga area in the city of Petrolina (Pernambuco State, Brazil). Honey samples were subjected to acetolysis, and the botanical affinity of the pollen types was identified. A total of 49 pollen types were found in the samples, with the predominant family being Fabaceae, comprising 16 distinct pollen types. The most frequent pollen type in terms of abundance and distribution was Mimosa tenuiflora. Most plants associated with the pollen types were nectariferous, with a shrubby habit, and native to Brazil. The greater richness of pollen types correlated with rainfall and temperature, showing high similarity between samples collected in months with higher precipitation due to the greater diversity of available flora.
Understanding the relationship between present-day pollen rain and natural vegetation provides a valuable analogue for interpreting fossil pollen records. In this study we obtained modern pollen assemblage data from 24 samples, collected from eastern, central and western parts of the Banni Plain, Kachchh Basin (Gujarat), India. The primary objective was to examine the relationship between the modern pollen-rain, extant vegetation and geomorphic surfaces in order to construct a reliable analogue for interpreting fossil pollen records with the aim of understanding the vegetation history and contemporary climate change within a defined area. The results showed over-representation of Rhizophora spp. (cf. Rhizophora mucronata), likely due to its anemophilous nature, whereas Sonneratia spp. (cf. Sonneratia apetala) and Avicennia spp. (cf. Avicennia marinata) are comparatively under-represented, suggesting their local presence. Aegiceras spp., and Bruguiera spp. (core mangrove taxa), as well as Nypa as a peripheral mangrove taxon and mangrove associates, have also comparatively lesser frequencies owing to entomophily. Herbaceous taxa like Poaceae, Cerealia and cultural pollen taxa are more prominent than arboreal taxa, suggesting human activity, soil erosion and grazing supported by cultural pollen and fungal spores (Sordaria, Podospora, and Glomus). These findings highlight the impact of both anthropogenic and ecological factors on western India's landscape facilitating palaeoecological research.
To gain insight into pollen-pollination adaptations, morphometric data of Adansonia digitata was prepared along 26 parameters, including novel and maiden aspects of the ratio of pollen tube emergence site and pollen surface area. The pollen grains were 3-4-zonoporate (primary character) with tenuimarginate granular margins, which provide elasticity for pore expansion and harmomegathy during pollen tube emergence. Pore openings, the sites of pollen-tube emergence, ranged from 18.08 mu m with 29.67 mu m annular ring to almost two times larger 38.46 mu m pores with 138.16 mu m annular ring and complete pore-apparatus, covered 2.45% to 4.59% pollen surface. The exine strata were homo- and hetero-punctitectate, rigid to homo-microreticulate, and elastic with variable spinules. The grains were medium-sized to large, with a circular outline and non-callotted mesocolpium. Pollen morphometry thus showed an affinity for zoophily against anemophily, with adaptations showing favourable pollen transport and landing on a stigmatic surface with proper apertural contact, which is essential for pollen-tube emergence. While serving as a genetically determined auxiliary diagnostic tool, the pollen analogue also substantiated the taxonomic status of the genus Adansonia L. in the tribe Adansonieae Horan., subfamily Bombacoideae (s.l.), family Malvaceae (s.l.). However, the magnitude of morphometric deviations from Bombacoideae, mainly the unique annulate pores bordered by thin, granular elastic margins, against pororate, colporate, and brevicolpate apertures having thick margins, and absence of mesocolpiar calotte, recommend independent subfamily status for the genus Adansonia. The resultant pollen analogue with innovative parameters also paved the way for future correlations of taxonomic traits, fossil counterparts, and evolutionary adaptations in species.
Aerobiology studies bioparticles in the air, encompassing their identification, behaviour, movement, survival, and impacts. Pollen and spores are the most studied particles due to their impact on public health and the economy. The prevalence of pollen allergy is increasing globally, including in Colombia. Preventing its consequences requires identifying airborne pollen, for which atlases are essential. The objective of this study was to develop the first aeropalynological atlas for Colombia and provide a historical account of aeropalynology in the country that allows for the diagnosis of the scenarios in which aerobiology has been developed and with which the research needed for Colombia in this field can be diagnosed. Based on an exhaustive bibliographic review and our own sampling, the most abundant or allergenic pollen types were selected, defined, described, and photographed. In addition, a historical account of aeropalynology in Colombia was compiled. The history of aeropalynology in the country is divided into three stages characterised by the methods used. The first stage comprised pioneering studies, the second stage involved an attempt to revive aerobiological research, and the third stage covers contemporary studies conducted between 2008 and the present. Throughout all studies, 68 pollen types were reported. In this work, we selected, defined, described, and photographed the 32 most abundant or allergenic pollen types. The evident and abundant presence of allergenic pollen in the atmosphere of Colombian cities in the past 80 years, together with its limited research, highlights the need and usefulness of the first aeropalynological atlas for the country.
Analysis of pollen viability and morphological characterisation of 20 coconut varieties (eleven tall, four dwarf, and five hybrids) was carried out to identify distinctive characteristics at the genotype level. Light microscopy (LM) and scanning electron microscopy (SEM) were used to study the morphology of pollen grains. Significant variations were observed in the morphology of pollen grains of different coconut varieties. Pollen from coconut varieties exhibited a monosulcate-elongated structure, ranging in shape from prolate to perprolate. The exine ornamentation was predominantly faveolate across these varieties. Significant differences were noted in polar axis length (P), equatorial axis length (E), P/E ratio, size index, and the number of pores per square micrometres. Hierarchical cluster analysis based on pollen characteristics delineated two major groups among the 20 varieties. The pollen morphology and viability can be considered as supplementary traits to enable fine differentiation of coconut accessions, in addition to other reproductive characteristics specific to palms used in coconut breeding.
This study documents the relationship between modern pollen deposition and vegetation types in the Jaintia Hills of Meghalaya, India. Five characteristic modern pollen assemblages are recognised based on the representation of marker pollen taxa observed in the surface soil samples obtained from different areas based on vegetation types and land use. The Pinus-Alnus-Betula-Quercus-Schima-Impatiens assemblage is associated with subtropical pine forest with a relatively cold and wet climate. The Schima forest is characterised by the Schima-Cinnamomum-Alnus-Quercus-Pandanus-Impatiens pollen assemblage. The evergreen forest is characterised by the Mesua-Syzygium-Duabanga-Ilex-Nepenthes-Dendrophthoe assemblage, indicative of the warm and wet climate in response to the high rainfall activity in this region. The grassland was characterised by the presence of the non-cereal-Cyperaceae-Pandanus-Schima-Asteroideae-Cichorioideae-Impatiens assemblage in the Jaintia Hills. The cropland was represented by cereal-Polygonum-Pinus-Schima-Nepenthes-Impatiens palyno-assemblages. Multivariate principal component analysis (PCA) was applied and showed a close correlation between the recorded pollen assemblage in relation to the different vegetation types in Jaintia Hills. The different forest types, especially evergreen and Schima wallichii (DC.) Korth., forests, along with the consistent recovery of Nepenthes and Pandanus pollen reflect the vicinity of coastal habitats in this part of the Indo-Burma region. This investigation demonstrates that this newly developed modern pollen analogue could be a potential proxy for the interpretation of palaeovegetation and palaeoclimate in the Jaintia Hills and other adjacent regions of the Indo-Burma biodiversity hotspot.
Modern pollen data are indispensable reference tools for reconstructing paleoenvironments and cultural landscapes. However, the importance of understanding the pollen released from Cannabis L. cultivation remains unexplored. Specifically, the role of Cannabis L. cultivation in the past and the current agricultural landscape has not been investigated, hindering efforts to understand its historical context in Morocco. This study assesses the representation of Cannabis L. pollen across land uses and variables. We conducted a pollen analysis on 40 moss samples collected from various altitudinal ranges across the Rif Mountains, a region known for its diverse agroforestry landscape and the cultivation of Cannabis L. The Cannabis pollen representation is highly variable across the variables (distance, land use, tree cover). The samples collected closest to the hemp fields registered Cannabis pollen levels reaching up to 25%, while a decrease (< 10%) was observed in samples collected 200 m away. The findings indicate that increased distance and tree cover harm the quantities of Cannabis pollen, whereas land use exhibited a positive correlation with Cannabis pollen levels. Moreover, other variables such as wind direction, field size, and geographical location of the field and sampling sites may impact the pollen amounts. We concluded that the quantity of Cannabis pollen in the region displays significant variation across various variables, indicating its potential for reconstructing the historical context of hemp in the Rif Mountains and identification of ancient cultivation trends. However, further research is needed to explore the relationship between Cannabis pollen production/dispersal patterns and other factors in more depth.
