Exploring microscopic pollen morphology in herbaceous Flora: Insights and analysis using scanning electron microscopy.

Microscopic techniques can be applied to solve taxonomic problems in the field of plant systematic and are extremely versatile in nature. This study was focused on the new approaches to visualizing the imaging, tool to cover the micro-structural techniques applied to the pollen study of flowers. The current research was proposed to evaluate microscopic pollen morphological attributes using light and scanning electron microscopy of herbaceous flora from Samarkand, Uzbekistan. A total of 13 herbaceous species, classified into 11 different families were collected, pressed, and identified, and then acetolyzed their pollen to visualize under light and scanning electron microscopy. Herbaceous flora can be characterized by small to very large-sized pollen morphotypes presenting four types of pollen shapes, prolate spheroidal (six species), spheroidal (three species) and prolate and oblate (two species each). The polar diameter and equatorial distance were calculated maximum in Hibiscus syriacus 110.55 and 111.2 µm respectively. Pollen of six different types was found namely tricolporate pollen observed in seven species, tricolpate and pantoporate in two species each, sulcate in Gagea olgae and hexacolpate pollen was examined in Salvia rosmarinus. Exine ornamentation of pollen was examined tectate perforate, verrucate-reticulate, micro-reticulate, reticulate, reticulate-cristatum, gemmate-echinate, echinate-perforate, perforate-striate, rugulate, rugulate-striate, bi-reticulate, reticulate-perforate and perforate-micro-reticulate showing great variations. Exine thickness was noted highest for Rosa canina 2.9 µm and minimum in Punica granatum 0.65 µm. This study of pollen imaging visualization of herbaceous flora contributes to the opportunity for the taxonomic evaluation of and fills knowledge gaps in studies of herbaceous flora identification using classical microscopic taxonomic tools for their accurate identification. RESEARCH HIGHLIGHTS: Pollen in unexplored herbaceous flora of the Samarkand region was studied with light and scanning electron microscopic pollen study. There is a high variation in observed pollen micromorphological characters. Pollen microscopic morphology has important taxonomic value for the identification of herbaceous species.

Pollen morphology of Acanthoideae species from the Shivalik Foothills in Rajaji National Park (Uttarakhand, India).

Apart from its role in plant taxonomy, the understanding of pollen morphology is considered an essential interdisciplinary tool in diverse applied fields, including plant systematics, melissopalynology, aeropalynology, forensic palynology, paleopalynology, and copropalynology. In palynotaxonomy, it is frequently employed to classify and validate natural groups across a range of hierarchical levels, from higher categories down to the infrageneric level. The subfamily Acanthoideae, within the Acanthaceae family, consists of a diverse group of flowering plants that are distributed globally. The present study attempted a comprehensive analysis of the pollen morphology, employing both light microscopy (LM) and scanning electron microscopy (SEM), for a total of 13 Acanthoideae species from the Shivalik Foothills in Rajaji National Park (located in the northern Indian state of Uttarakhand, Western Himalaya). The findings indicated that the Acanthoideae is characterized by eurypalynous features, and the studied species exhibited pollen grains that were monads, radially symmetrical, and varied in size from small to large. The pollen grains were predominantly tricolporate or heteroaperturate, with porate occurrences being rare. The significant variation in exine sculpturing, including reticulate, coarsely reticulate, and bireticulate patterns, holds substantial taxonomic significance. The detailed presentation encompasses pollen morphological characters described with LM and SEM micrographs, along with a species-level identification key. RESEARCH HIGHLIGHTS: This article provides a thorough analysis of the pollen morphology of Acanthoideae taxa using both light microscopy and scanning electron microscopy, covering 13 species across 10 genera and revealing a broad spectrum of pollen characteristics, including size, shape, aperture type, and exine sculpturing. The microscopic investigation of these Acanthoideae species not only enhances our understanding of their pollen morphology but also aids in species identification through the development of a pollen-based key.

Scanning electron microscopic exploration of intricate pollen morphology and antimicrobial potentials of gourd family.

This study employs scanning electron microscopy (SEM) to delve into the intricate pollen morphology of Cucurbitaceae (Gourd Family) species, unraveling the nuanced details of their structural features. Concurrently, the research investigates the antimicrobial potentials encoded within these pollen grains, shedding light on their possible applications in the realm of natural antimicrobial agents. Cucurbitaceae plants showcases significant antibacterial and antifungal potentials, underscoring its potential as a source for novel antimicrobial compounds. This research endeavors to provide a comprehensive analysis of pollen morphometry in 12 Cucurbitaceous species, with the primary goal of identifying pollen morpho-types to enrich the taxonomic understanding of the Cucurbitaceae. Following the Erdtman protocol, the study involved processing, measuring, and capturing pollen grains using SEM techniques. Qualitative data were analyzed to evaluate the variations in pollen types, size, and exine stratified sculptured layering. The pollen grains exhibit characteristics of being monads, ranging in size from medium to very large, with the prevailing shape being prolate-spheroidal in six species. Notably, the maximum polar axis diameter was recorded for Cucurbita pepo (106.3 µm), while the minimum was observed in Zehneria anomala (32.6 µm). The grains of Cucurbitaceae exhibit diverse surface patterns, including reticulate columellae, reticulate, verrucate-scabrate, verrucate-gemmate, echinate baculate, reticulate-perforate, and micro-reticulate. This SEM investigation illuminates the intricacies of Cucurbitaceae pollen morphology while concurrently highlighting their noteworthy antimicrobial potentials. HIGHLIGHTS: High-resolution imaging reveals complex pollen morphology. Identification of unique antimicrobial structures on Cucurbitaceae pollen (gourd family). Exploring medicinal potential: Antimicrobial properties of cucurbitaceae species.

Revealing the intricate microcosm: Advancing invasive species pollen analysis through scanning microscopy of ultra sculpture.

Micromorphological visualization of plant surface peculiarities provides valuable characters for the precise identification of plant species. Invasive alien species, introduced outside their native range, pose significant ecological, and health challenges. This study focuses on micromorphological investigations of selected invasive plant species belonging to the families Amaranthaceae, Asteraceae, Moraceae, Crassulaceae, Cannabaceae, Fabaceae, Commelinaceae, and Oxalidaceae. The study employs scanning electron microscopy (SEM) to analyze the species micromorphology of pollen structure in depth to characterize the sculpturing patterns. Additionally, the study examines the pollen characteristics of these invasive plants, including shape, size, and fertility, along with exine sculpturing. The maximum polar diameter was observed for Senna tora (41.2 µm). The spines in Achillea fragrantissima were measured to have dimensions of approximately 1.91 µm in length and 2.11 µm in width. The findings shed light on the allergy-causing potential of these invasive species, providing crucial information for accurate identification and effective management strategies to safeguard the indigenous flora of the region. The study contributes to the knowledge base for botanists, taxonomists, policy makers, climate experts, and biodiversity specialists. RESEARCH HIGHLIGHTS: Integrating SEM to analyze the pollen of invasive species. Unveiling pollen micromorphology of invasive species. Exploring the microscopic realm of invasive pollen to accurately identify the species.

Unveiling the intricacies of Amaranthaceous pollen diversity: Advancing ultra sculpture analysis through LM and SEM.

Microscopic techniques can be applied to solve taxonomic problems in the field of plant systematic and are extremely versatile in nature. This study was focused on the new approaches to visualizing the imaging, tool to cover the micro-structural techniques applied to the pollen study of Amaranthaceae floral biology. In this detailed study, we used light microscopy and scanning electron microscopy to examine the shape and changes in pollen of 16 types of Amaranthaceae plants from the salty arid zone of Riyadh Saudi Arabia. We observed subtle variations among the studied species through meticulous examination of morpho-palynological features such as symmetry, size, shape, pore ornamentation, and exine characteristics. The pollen grains were round and had rough or prickly outer coverings. They had different numbers of tiny pores; some were slightly sunken. These findings were utilized to develop a pollen taxonomy key, facilitating accurate identification and classification of Amaranthaceous species. Our results shed light on the taxonomic significance of pollen morphology for species differentiation within the Amaranthaceae family. Furthermore, this study provides valuable insights into the influence of geographical and ecological factors on pollen diversity and evolution. This study of pollen imaging visualization of Amaranthaceous species contributes to the opportunity for taxonomic evaluation and fill knowledge gaps in studies of Amaranthaceous flora identification using classical microscopic taxonomic tools for their accurate identification. RESEARCH HIGHLIGHTS: The pollen characters of selected Amaranthaceae species were visualized using scanning electron microscopy to observe sculptural wall pattern. The comprehensive Amaranthaceous pollen examination approach allowed us to accurately identify their micromorphology. This high-resolution imaging technique provided detailed insights into the surface structures and ornamentation of the pollen grains.

Floral micromorphological, palynological, and carpological characteristics of the rare endemic Korean species Peucedanum miroense (Apiaceae).

Peucedanum miroense K. Kim, H.-J. Suh & J.-H. Song, recently reported as a new species endemic to South Korea, is distributed on mountains Duta-san and Swinum-san in Gangwon Province, South Korea. Given its conspicuously limited habitat range and small populations, this species qualifies as an endangered Red List species. In this study, we undertook a detailed investigation of the floral micromorphological, palynological, and carpological characters of P. miroense based on a range of microscopic analyses. Examination of the floral micromorphology of P. miroense revealed that the surface patterns of bractlets have potential utility in taxonomy studies of the genus Peucedanum. In addition, we established that this plant is characterized a papillose conical-tabular rugose pattern of petal epidermal cells and bears sunken nectary slits on the stylopodium. Also identified were simple spherical orbicules bearing psilate surface ornamentation, as well as small tricolporate prolate to perprolate pollen grains characterized by verrucate and gemmate ornamentation. Moreover, we verified pollen wall stratification and presence of pollenkitt. The mericarps had colliculate-striate surface patterns with trichomes and eight or nine vittae, and prismatic crystals were detected in different layers of the pericarp. We believe that the findings of this study will contribute to an evaluation of the taxonomic significance of this species within the genus Peucedanum, and also provide valuable information for the conservation of this rare endemic species. RESEARCH HIGHLIGHTS: We provided the first detailed descriptions of the floral micromorphological, palynological, and carpological characters of the rare endemic Korean species Peucedanum miroense K. Kim, H.-J. Suh & J.-H. Song, based on different microscopic analyses. Our findings provide valuable information regarding the epidermal cell patterns of bractlets, petals, stylopodium, gynoecium, and anthers. We believe our study makes a significant contribution to the literature, as our findings will contribute to enhancing the taxonomical classification of species within the genus Peucedanum, and will provide a basis for the conservation of this rare endemic species. This results will be of value to researchers studying the future biology and taxonomy of species within the family Apiaceae, particularly those using different microscopic techniques, including FE-SEM, digital slide scanning, and TEM.

Single-frame 3D lensless microscopic imaging via deep learning.

Since the pollen of different species varies in shape and size, visualizing the 3-dimensional structure of a pollen grain can aid in its characterization. Lensless sensing is useful for reducing both optics footprint and cost, while the capability to image pollen grains in 3-dimensions using such a technique could be truly disruptive in the palynology, bioaerosol sensing, and ecology sectors. Here, we show the ability to employ deep learning to generate 3-dimensional images of pollen grains using a series of 2-dimensional images created from 2-dimensional scattering patterns. Using a microscope to obtain 3D Z-stack images of a pollen grain and a 520 nm laser to obtain scattering patterns from the pollen, a single scattering pattern per 3D image was obtained for each position of the pollen grain within the laser beam. In order to create a neural network to transform a single scattering pattern into different 2D images from the Z-stack, additional Z-axis information is required to be added to the scattering pattern. Information was therefore encoded into the scattering pattern image channels, such that the scattering pattern occupied the red channel, and a value indicating the position in the Z-axis occupied the green and blue channels. Following neural network training, 3D images were formed from collated generated 2D images. The volumes of the pollen grains were generated with a mean accuracy of ∼84%. The development of airborne-pollen sensors based on this technique could enable the collection of rich data that would be invaluable to scientists for understanding mechanisms of pollen production climate change and effects on the wider public health.

Comparative light and scanning electron microscopic studies of pollen of two marijuana species causing allergies.

Marijuana (Cannabis) belongs to family Cannabaceae. This plant is a great natural source of cannabinoids, which have several medical applications such as it is used for the treatment of anxiety and psychosis, disorders of motility and epilepsy. However, this plant is also notorious for its pollen allergic reactions. Mainly two species, that is, C. sativa L. and C.indica Lam. are involved in allergic reactions. In this study, morpho-palynological studies of both the species were conducted. A number of morphological differences were observed in the both species. C. sativa is tall with narrowed leaves and fibrous stalk plant while C. indica is short, bushier, broad leaves, and having woody stalk plant. Both the species are varied in their pollen characteristics. The polar diameter of C. sativa observed was 7.5 µm and equatorial diameter was 8 µm, and its shape was oblate-spheroidal. C. indica had 7 µm polar diameter, 7.5 µm equatorial diameter but its shape was similar to C. sativa, that is, oblate-spheroidal. About 40%-50% people were affected with both these marijuana species and had symptoms of allergies like dry cough, congestion, itchy eyes, sore throat, nausea, a runny nose, watery eyes, and sneezing. It was concluded that both species' pollen are allergy causing and pollen of both species are different with variations in morphological and allergic symptoms. RESEARCH HIGHLIGHTS: Marijuana has great therapeutic importance but it is also notorious for its pollen allergic reactions. Two species of Marijuana, that is, Cannabis sativa L. and Cannabis indica Lam mainly responsible for these pollen allergies. The present research work focused the morpho palynological analysis of these two Marijuana species through light and scanning electron microscopy.

Microscopic (LM and SEM) visualization of pollen ultrastructure among honeybee flora from lower Margalla Hills and allied areas.

Microscopic visualization of micro-morphological characters were analyzed using a scanning electron microscopic (SEM) tool, which has proven to be very successful to analyze the pollen surface peculiarities. The significant goal of this research was to perform microscopic examination of pollen of some of the most frequently visited honeybee floral species around apiaries. Micro-morphological characterization of frequented honeybees foraged plants were discussed. A total of 15 species, belonging to 11 different families were identified for the foraging activities of honeybees, namely, Lantana camara, Jatropha integerrima, Helianthus annuus, Tecoma stans, Lagerstroemia indica, Duranta erecta, Cosmos sulphureus, Hymenocollis littoralis, Moringa oleifera, Cestrum nocturnum, Parthenium hysterophorus, Volkameria inermis, Catharanthus roseus, Malvastrum coromandelianum, and Citharexylum spinosum. The microscopic slides were prepared using the acetolysis method, and the qualitative and quantitative features were measured and described using microscopic tools. The pollen type sculpture varies from psilate scabrate to echinate and colpi from tricolpate to tetracolpate. Quantitative parameters such as polar diameter, mesocolpium distance, equatorial dimensions, aperture size, spine diameter, and exine thickness were calculated using IBM SPSS Statistics 20. The exine thickness was measured at its maximum in C. roseus (3.85 µm), whereas it was at its minimum of 0.90 µm in L. indica and D. erecta. Pollen fertility was estimated to be highest in H. annus (88%). The current research validates scanning microscopic features of pollen of the honeybee floral species, which is helpful for the accurate identification and commercializing of honey production to generate revenue for beekeepers through the exploration of bee floral diversity. RESEARCH HIGHLIGHTS: Pollen spectrum examination using microscopic imaging techniques. Variations examined through scanning microscopy in pollen ultrastructure. Micro-morphology has taxonomic value for accurate identification of honeybee flora. Authentication of Honeybee floral species for sustainable beekeeping.

Morpho-palynological and anatomical studies in desert cacti (Opuntia dillenii and Opuntia monacantha) using light and scanning electron microscopy.

Opuntia is the most diverse and widely distributed drought resistant promising genus of family Cactaceae. The cladodes were utilized to quantify the chemical composition of these plants helpful in lignocellulose conversion and their application towards biofuel production. The present study was aimed to evaluate and compare the taxonomic relationship based on morphology, stem anatomy and palynology of important desert cacti including Opuntia dillenii and Opuntia monacantha. This study also evaluates the potential usefulness of morphological, anatomical and pollen traits using light and scanning electron microscopy. The obtained microcharacters of stem and flowers are considered diagnostic at the generic and specific levels. Some distinguishing morphological features observed were elliptical to obovate cladodes, 1-7 spines per areole and presence of glochidia in O. dillenii. Pollen and stem anatomical characters of the studied taxa are considered highly diagnostic at the generic and species levels. The epidermis has irregular and wavy cells, with straight to sinuate wall pattern and paracytic stomata. Pollen grains appear as pantoporate and prolate spheroidal having reticulate to perforate-reticulate sculpturing while exine semi-tectate to tectate. The taxonomic features studied could be valuable to elaborate and helpful in correctly identification of Opuntia species. The methods of diverse microscopic examination also providing sufficient evidence about the taxonomy of the Opuntia species. RESEARCH HIGHLIGHTS: Description and illustration of desert cacti Opuntia. Morpho-anatomy and palynology were studied with LM and SEM. Highly variation in taxonomic qualitative and quantitative features. Systematic significance based on taxonomic characters was presented.

Light and scanning electron microscopic characterization of pollen grains of some wetland angiosperms from India.

Pollen grains of 58 wetland species of angiosperms belonging to 17 families, growing in different wetlands of Sub-Himalayan biodiversity hotspots, Northern Bengal and lower Gangetic plains, India were investigated during a 4-year span of 2015-2019. Freshly collected anthers were processed through the acetolysis method and the obtained pollen grains were accurately studied under LM and SEM and properly photographed. Different attributes viz. shape, size, aperture type and exine ornamentation of pollen grains served as consistent features were used for authentic identification of the studied species. To study the phylogeny of pollen grains, characters like polarity, symmetry, aperture and exine sculpturing were found most significant for species segregation. Investigated pollen grains were mostly prolate-spheroidal, spheroidal or triangular, rarely prolate or elongated, exine psilate, granulate, reticulate or microechinate type. Most of the observable aperture of pollen grains of studied species were colporate, colpate and porate, while ulcerate and inaperturate grains were also observed in the studied aquatic members of the families Cyperaceae and Potamogetonaceae. All the gathered data were further statistically analyzed through ANOVA, PCA and Pearson Correlation Matrix to understand the interrelationship among the species. The permanent slides of identified pollen grains were deposited at the herbarium of North Bengal University [NBU] for future references. HIGHLIGHTS: Study of Pollen morphology of 58 wetland species under light & scanning electron microscopy. Unique apertures and exine ornamentation used to understand taxonomic evaluation of studied species. Pollen character supports interrelationship among the studied species. Relationship between exine thickness and the habitat of the wetland plants.

Light and scanning electron microscopic observation of palynological characteristics in spineless Astragalus L. (Fabaceae) and its taxonomic significance.

Palynological characterization is considered to be one of the significant taxonomic tools for the delimitation and identification of morphologically complicated taxa. Hence, the pollen morphology of 12 species of spineless Astragalus L. was examined using light and scanning electron microscopy. Studied pollen were small to medium, monad, prolate to per-prolate and tricolporate type in all studied taxa. The exine sculpturing varied from reticulate to microreticulate whereas colpus ornamentation ranged from scabrate to granulate. Furthermore, maximum polar and equatorial diameter was recorded in Astragalus leucocephalus Bunge. (45.00 µm) and A. pyrrhotrichus Boiss. (22.91 µm) while minimum in A. amherstianus Benth. ex Royle (28.75 µm) and A. amherstianus Benth. ex Royle (15.00 µm), respectively. Similarly, the ratio of polar to equatorial diameter was recorded maximum in A. ophiocarpus Boiss. (2.05). The width of colpi was larger in A. hamosus L. (1.29 µm) and smaller in A. ophiocarpus Boiss. (0.62 µm). We have also found the maximum value of mesocolpium in A. retamocarpus Boiss. (2.08 µm) while minimum in A. oxyglottis Steven ex M.Bieb. (1.87 µm). The quantitative pollen attributes helped in the development of pollen keys for the accurate and quick identification of the studied species. Furthermore, ordination and cluster analysis were performed for the differentiation of the investigated taxa at species level. Based on our results, we conclude that pollen features can be used for the delimitation and identification of the studied taxa. RESEARCH HIGHLIGHTS: Pollen micromorphology is a useful tool for classifying complicated taxa. The pollen micromorphology of 12 spineless species of Astragalus L. was studied using LM and SEM. The observed pollen characteristics aided in Astragalus L. serve for the identification and classification of taxa at specific level.

Micro-morphological diversity of pollen among Asteraceous taxa from Potohar Plateau-Pakistan.

Microscopic pollen characters from 19 species of family Asteraceae collected from different areas of the Potohar Plateau of Pakistan have been investigated using light and scanning electron microscopy. This study uses microscopic techniques to provide detailed information on pollen and its exine structure based on qualitative and quantitative characters. The present study has observed three types of pollen grains based on their apertures, that is, trizonocolporate, tetrazonocolporate, and tricolporate. Exine sculpturing is echinate in all studied taxa. Some species also exhibit Lacunae which differ in their shape and sizes. The size of the spines and the number of spines between the colpi play a vital role in differentiating the species of the same genus. Pollen fertility ranges from 94.3 to 74.19, showing that these species are well established in the study area. For the correct identification of species, a light and scanning electron microscopy was used that provides sufficient information for a taxonomist to distinguish species taxonomically. RESEARCH HIGHLIGHTS: Light and Scanning electron microscope is comparatively used to investigate the pollen characters of some species of the family Asteraceae. A scanning electron microscopy is used to study the micro-morphological characters of pollen grains. Qualitative and quantitative characters of pollen were studied.

Palyno-morphological diversity of Asteraceous and Poaceous allergenic plant using microscopic techniques in lesser Himalaya-Pakistan.

In classification and identification of plant species, palyno morphological character has remain helpful for plant taxonomist. The aim to investigation this study was to identify the characteristic features of Asteraceae and Poaceae family member collected from lower Himalayas of Pakistan. Light microscope and Scanning electron microscope were used for feature study of allergenic pollen. Our study includes 10 species of Asteraceae and Poaceae family. The most dominant shape of pollen was Oblate-spheroidal, Prolate-Spheroidal, Prolate and Suboblate shape of pollen. Quantitative character of pollen includes maximum pollen diameter found in Dichanthium annulatum (46.0 µm) and minimum polar axis pollen diameter found in Parthenium hysterophorous (16.0 µm). Similarly highest value of P/E ratio was noted in Cenchrus echinatus (1.05) and smallest value of P/E ratio was observed in Erigeron bonariensis (0.88). Poaceae family member were monoporate. Character feature of exine sculpturing include Microechinate, granulate, echinate, conical base, lacunae Nanogammate, Aerolate-Scabratre, Verrucate, like variation found in exine of both family member. Highest value of pollen fertility was observed in P. hysterophorous 93%, Similarly maximum value of pollen sterility was noted in E. bonariensis and Brachiaria reptans 24%. This investigation provides the characteristic feature of allergenic pollen species and help to arrange them in define class. RESEARCH HIGHLIGHTS: Pollen has affected many people around the world. Using microscopic techniques, morpho-palynological analysis of Asteraceae and Poaceae families were recognized. LM and SEM study show both qualitative and quantitative character of pollen. Identification of allergenic pollen and microscopic identified character play important role for proper guideline of identification of pollen having allergenic potential.

Pollen morphology and its implication in the taxonomy of some selected taxa of the bi and tri-ovulate Euphorbiaceae of the Hainan Island by using multiple microscopic techniques.

The family Euphorbiaceae is one of the most taxonomically complex and diverse family among the angiosperm. Therefore, this study aims to document the pollen morphology of the Euphorbiaceae taxa collected from different geographical regions of the Hainan Island South China, to strengthen the taxonomy and support the subfamilial classification. The Euphorbiaceae includes 23 species and 10 genera of the bi-ovulate subfamily Phyllanthoideae and tri-ovulate Crotonoideae, Euphorbioideae, and Acalyphoideae were examined under light and scanning electron microscopy. The principal component analysis was performed by using six variables to show variation and relationships between the species. A significant variation was found in the pollen morphology (exine and colpus sculpturing). The croton-type pattern of the pollen was found the diagnostic trait of the Crotonoideae. The Euhphorboideae taxa were mostly homogenous however, variation was found in the muri pattern. The Acalyphoideae, have fossulate scabrate and verrucate exine sculpturing that can delimit from the rest of sub-families. The Phyllanthoideae, showed reticulate exine, tri to tetra-colporate having various colpus morphology. The maximum pollen size was found in Croton hirtus (59.49 × 60.86 µm) and minimum in Acalypha indica (10.86 × 73 µm). Similarly, the maximum colpus width was observed in Euphorbia pulcherrima (8.3 µm). Hence pollen traits have relevance in the taxonomy and phylogenetic of the family to define species boundaries at various taxonomic levels. This study can support and strengthen the taxonomy of subfamilies and fill the palynological gap of these taxa in Hainan Island and will contribute to future systematic studies of the Euphorbiaceae.

Authentication of the therapeutic Lamiaceae taxa by using pollen traits observed under scanning electron microscopy.

Herbal medicines are gaining popularity worldwide for human healthcare because of their therapeutic potential. However, adulteration and use of unauthentic raw herbals as substitutes have become a major issue for the local communities and industry for reasons of safety and efficacy. Therefore, the authentication of medicinal plants before their use in herbal medicines is a need of time. Hence, the present study was designed with an aim, to authenticate the therapeutic Lamiaceous taxa by using pollen traits observed under scanning electron microscopy. Pollen micro-morphological studies solve the problem through discrimination and correct identification of the Lamiaceae species from the adulterants. Based on pollen features, Lamiaceae were further divided into two sub-families Lamioideae (tricolpate) and Nepetoideae (hexa-colpate). The pollen grains of Lamioideae were found as small to medium-sized, tricolpate, radially/bilateral symmetrical, sub-spheroidal and oblate shape. Besides, exine patterns bireticulate, reticulate and micro-reticulate, colpus surface sculpturing as psilate, gemmate, scabrate, and verrucate have also been reported. A significant variation was found in the pattern of the reticulum, thickness, and the number of secondary lumina per primary lumen. Similarly, Nepetoideae has a hexa zono-colpate pollen but tri and tetra zono-colpate pollen have also been observed. Hence, this study contributes to the authentication and correct identification of medicinally important Lamiaceae taxa by using scanning electron microscopic techniques and can help to solve the adulteration problem. Highlights Authentication of medicinally important Lamiceous taxa was carried out through scanning electron microscopic techniques. Chemotaxonomic characterization was used for the accurate identification of the therapeutic taxa. The medicinal, palynological and phytochemical significance of Lamiaceae taxa were evaluated. A significant variation was seen in the palynological traits that help in the determination and authentication of the therapeutic Lamiaceous species. Based on the chemotaxonomic characterization, our study can help to solve the adulteration problem for the reason of safety and efficacy.

Palyno-anatomical microscopic characterization of selected species of Boraginaceae and Fabaceae.

Palyno-anatomical characterization of some selected species of Boraginaceae and Fabaceae using light microscopy (LM) and scanning electron microscopy (SEM) was conducted. Six species of them belongs to four genera of family Boraginaceae and other six species belongs to four genera of Fabaceae. The current study aimed to investigate palyno-anatomical features for correct identification and taxonomic significance. Pollen grains were acetolyzed and observed both qualitatively and quantitatively through light microscopy and scanning electron microscopy. Statistical data was analyzed through cluster analysis which categorized plants into clusters. Principal component analysis (PCA) was carried out to illustrate morphological variation among selected plant species. Studied plant species showed variation in shape, size, aperture type, exine ornamentation of pollen, size and shape of epidermal cells, types of stomata, guard cells, subsidiary cells and trichome types. Exine thickness was recorded maximum 2.30 ± 0.1 µm in Lablab purpureus and minimum 1.05 ± 0.2 in Gastrocotyle hispida. PCA summarized 73.78% of accumulative variance. Trichome index was observed highest 62% on the adaxial surface of Heliotropium europaeum and lowest 21% on adaxial surface of L. purpureus. These findings reinforce the importance of palyno-anatomical features in the characterization and identification of taxa. It was concluded that description of palyno-anatomical characteristics presented in this study, highly contribute to our knowledge for correct identification of plant species.

Scanning electron microscopic imaging of palynological metaphors: A case study of family Poaceae taxa.

This study highlighted the taxonomic utilization of palynological metaphors for selected members (53) of family Poaceae. Multiple microscopic technique light and scanning electrons had been employed for detailed analysis. Results reported monad pollen type in all studied 53 members, which showed its limited taxonomic value up to family level. In relation to shape of pollen both polar and equatorial views strikingly differed from each other. Like semi angular pollen observed in Dactyloctenium aegyptium (L.) Wild. whereas round-minutely irregular pollen in Lolium temulentum L. Polar and equatorial diameter also showed variation, that is, Desmostachya bipinnata (L.) Stapf. can be differentiated from Sorghum bicolor (L.) Moench on diameter variation basis. A pore characteristic does not show much qualitative variation; however pore sizes differ species to species. The most frequently scarbate sculpturing was observed in 28 species followed by verrucate. Hence it can be said that pollen shape, polar, and equatorial diameters, pore size, P/E ratio, pore sculpturing are of good taxonomic value and holds a significant position in identification and delimitation of Poaceae taxa.

Dynamic changes in primexine during the tetrad stage of pollen development.

Formation of pollen wall exine is preceded by the development of several transient layers of extracellular materials deposited on the surface of developing pollen grains. One such layer is primexine (PE), a thin, ephemeral structure that is present only for a short period of time and is difficult to visualize and study. Recent genetic studies suggested that PE is a key factor in the formation of exine, making it critical to understand its composition and the dynamics of its formation. In this study, we used high-pressure frozen/freeze-substituted samples of developing Arabidopsis (Arabidopsis thaliana) pollen for a detailed transmission electron microscopy analysis of the PE ultrastructure throughout the tetrad stage of pollen development. We also analyzed anthers from wild-type Arabidopsis and three mutants defective in PE formation by immunofluorescence, carefully tracing several carbohydrate epitopes in PE and nearby anther tissues during the tetrad and the early free-microspore stages. Our analyses revealed likely sites where these carbohydrates are produced and showed that the distribution of these carbohydrates in PE changes significantly during the tetrad stage. We also identified tools for staging tetrads and demonstrate that components of PE undergo changes resembling phase separation. Our results indicate that PE behaves like a much more dynamic structure than has been previously appreciated and clearly show that Arabidopsis PE creates a scaffolding pattern for formation of reticulate exine.

Morpho-Physiological and Transcriptome Changes in Tomato Anthers of Different Developmental Stages under Drought Stress.

Drought limits the growth and productivity of plants. Reproductive development is sensitive to drought but the underlying physiological and molecular mechanisms remain unclear in tomatoes. Here, we investigated the effect of drought on tomato floral development using morpho-physiological and transcriptome analyses. Drought-induced male sterility through abnormal anther development includes pollen abortion, inadequate pollen starch accumulation and anther indehiscence which caused floral bud and opened flower abortions and reduced fruit set/yield. Under drought stress (DS), pollen mother cell to meiotic (PMC-MEI) anthers survived whereas tetrad to vacuolated uninucleate microspore (TED-VUM) anthers aborted. PMC-MEI anthers had lower ABA increase, reduced IAA and elevated sugar contents under DS relative to well-watered tomato plants. However, TED-VUM anthers had higher ABA increase and IAA levels, and lower accumulation of soluble sugars, indicating abnormal carbohydrate and hormone metabolisms when exposed to drought-stress conditions. Moreover, RNA-Seq analysis identified altogether >15,000 differentially expressed genes that were assigned to multiple pathways, suggesting that tomato anthers utilize complicated mechanisms to cope with drought. In particular, we found that tapetum development and ABA homeostasis genes were drought-induced while sugar utilization and IAA metabolic genes were drought-repressed in PMC-MEI anthers. Our results suggest an important role of phytohormones metabolisms in anther development under DS and provide novel insight into the molecular mechanism underlying drought resistance in tomatoes.