scholarly journals Pollen morphological variability correlates with a large-scale gradient of aridity

Web Ecology ◽  
2020 ◽  
Vol 20 (1) ◽  
pp. 19-32 ◽  
Author(s):  
Hindel Fatmi ◽  
Souhaïl Mâalem ◽  
Bouchra Harsa ◽  
Ahmed Dekak ◽  
Haroun Chenchouni
Keyword(s):  
Large Scale ◽  
Morphological Variability ◽  
Pollen Grains ◽  
Dry Season ◽  
Pollen Grain ◽  
Climatic Zones ◽  
Atriplex Halimus ◽  
Climate Gradients ◽  
Trade Offs ◽  
Pollen Types

Abstract. The study of the morphology of living organisms is essential to understand their evolution and diversity. This study aims to determine the importance of climatic gradients in the diversity of pollen morphotypes using Atriplex halimus L. (Amaranthaceae) as a model species. Atriplex halimus is a perennial shrubby plant, polymorphic and very resistant to severe environmental conditions. In seven bioclimatic zones, ranging from mesic conditions in the north to hot–hyperarid in the south, pollen samples were collected from 49 sites, with seven accessions per bioclimate. Under a light microscope, pollen grains were selected and analyzed from three anthers of different flowers. Besides the usual pollen grain types, some previously unknown morphotypes, such as sulcate, triangular, and ovoid, were observed and described at the different climatic zones. A total of 10 pollen grain shapes were quantified and discussed following their specific occurrences within different climatic zones. Occurrence frequencies of different pollen shapes ranged between 0 % and 85.7 %, where the pantoporate spheroidal was the most widespread in all climatic zones, especially in the desert climate (85.7 %). Five pollen types occurred exclusively once per climate zone. The pantoporate prolate spheroidal in mesomediterranean climate with a long dry season (28.6 %), sulcate in the xerothermomediterranean climate (14.3%), pantoporate subtriangular in the subdesert climate with a short dry season (14.3 %), and pantoporate subprolate and boat-shaped in a subdesert climate with a long dry season with 14.3 % for each. Our findings help to understand the evolutionary effects of climate gradients on pollen morphology and variability in arid and desert areas and point towards a high degree of specialization in order to maximize trade-offs between pollination efficiency and protection of pollen grains from dehydration.

scholarly journals Precise Pollen Grain Detection in Bright Field Microscopy Using Deep Learning Techniques

Sensors ◽  
2019 ◽  
Vol 19 (16) ◽  
pp. 3583 ◽  
Author(s):  
Ramón Gallardo-Caballero ◽  
Carlos J. García-Orellana ◽  
Antonio García-Manso ◽  
Horacio M. González-Velasco ◽  
Rafael Tormo-Molina ◽  
...  
Keyword(s):  
Network Architecture ◽  
Detection System ◽  
Pollen Grains ◽  
Pollen Grain ◽  
Average Value ◽  
Pollen Types ◽  
Pollen Concentrations ◽  
Pollen Counting ◽  
Estimation System ◽  
3D Information

The determination of daily concentrations of atmospheric pollen is important in the medical and biological fields. Obtaining pollen concentrations is a complex and time-consuming task for specialized personnel. The automatic location of pollen grains is a handicap due to the high complexity of the images to be processed, with polymorphic and clumped pollen grains, dust, or debris. The purpose of this study is to analyze the feasibility of implementing a reliable pollen grain detection system based on a convolutional neural network architecture, which will be used later as a critical part of an automated pollen concentration estimation system. We used a training set of 251 videos to train our system. As the videos record the process of focusing the samples, this system makes use of the 3D information presented by several focal planes. Besides, a separate set of 135 videos (containing 1234 pollen grains of 11 pollen types) was used to evaluate detection performance. The results are promising in detection (98.54% of recall and 99.75% of precision) and location accuracy (0.89 IoU as the average value). These results suggest that this technique can provide a reliable basis for the development of an automated pollen counting system.

The importance of being the first pollen in the strobili of Scots pine

2008 ◽  
Vol 38 (12) ◽  
pp. 2976-2980 ◽  
Author(s):  
Saila Varis ◽  
Arja Santanen ◽  
Anne Pakkanen ◽  
Pertti Pulkkinen
Keyword(s):  
Pinus Sylvestris ◽  
Scots Pine ◽  
Pollen Grains ◽  
Seed Orchard ◽  
Pollen Grain ◽  
Seed Orchards ◽  
Pollination Experiments ◽  
Seed Crop ◽  
Pollen Types ◽  
Pine Pollen

Timing of pollen arrival may affect the level of seeds fertilized by pollen from outside seed orchards, especially in seed orchards of Scots pine ( Pinus sylvestris L.) established in southern Finland with stock from northern populations. We performed sequential pollination experiments with Scots pine pollen collected from seed orchard clones originating from southern and northern Finland and recipient strobili in clones originating from southern Finland. When southern pollen was introduced first, seeds were sired equally by northern and southern genotypes. When northern pollen was introduced first, northern genotypes were found in 75% of the resulting seeds. When both pollen types were introduced at the same time, the resulting seed crop was split almost equally between northern and southern genotypes. These results do not unconditionally support the idea that the first pollen grain in the pollen chamber always fertilizes the ovum; instead, they suggest a more complex way of competition between pollen grains.

scholarly journals SCANNING ELECTRON MICROSCOPY STUDIES ON PLECTRANTHUS- AN IMPORTANT BEE FORAGE PLANT OF HIMACHAL PRADESH, INDIA

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Radhika Jamwal
Keyword(s):  
Electron Microscopy ◽  
Pollen Grains ◽  
Himachal Pradesh ◽  
Pollen Grain ◽  
Surface Pattern ◽  
Climatic Zones ◽  
Forage Plants ◽  
Shape Class ◽  
Symmetry Surface ◽  
Scanning Electron

The present investigations were conducted on two important nectar and pollen yielding plants viz. Plecranthus coesta and Plecranthus rugosus from different agro-climatic zones of Himachal Pradesh. The bee forage plants were collected, identified, classified and diffentiating characters of two species were noted. Apart from this, pollen grains of P. coesta and P. rugosus were also studied using light and scanning electron microscope. The pollen grains were observed in terms of aggregation, shape, shape class, size, aperture, polarity, symmetry, surface pattern/exine complexity. Both P. coesta and P. rugosus had solitary medium sized, hexacolpate, isopolar and radially symmetric grains. However, the pollen grain of two species varies in shape and exine complexity. P. coesta pollens were round/ circular and were prolate, whereas in P. rugosus pollens were round/oval and subprolate-prolate. Variation was also found in the exine complexity of the two species. Exine was tectate, tectum was nearly reticulate / scabrate in P. coesta. But in P. rugosus and exine was either tectate or semitectate, tectum was reticulate, microreticulate.

scholarly journals EL POLEN DE HELICTERES (STERCULIACEAE) y SU COMPARACIÓN CON GÉNEROS VECINOS

Bonplandia ◽  
2001 ◽  
Vol 11 (1-4) ◽  
pp. 207 ◽  
Author(s):  
Stella M. Piré ◽  
Carmen L. Cristóbal
Keyword(s):  
Pollen Grains ◽  
Pollen Grain ◽  
The Other ◽  
Type I ◽  
Evolutionary Trend ◽  
Equatorial Zone ◽  
Pollen Type ◽  
Type Viii ◽  
Exine Sculpture ◽  
Pollen Types

<p>Pollen grains of 41 species representing all seven sections of Helicteres were studied with light and scanning electron microscopy and described. In order to establish palynological affinities Neoregnellia cubensis, Kleinhovia hospita, Reevesia thyrsoidea, Veeresia clarkii, Ungeria floribunda and Pterospermum acerifolium were also examined. Helicteres is palynologically rather uniform with respect to the shape and size of the grains as well as the type and number of the apertures. The pollen grains are usually triporate, oblate or suboblate, amb triangular and medium sized. Nevertheless the exine surface shows great variability. Nine pollen types are recognized on the basis of the sculpture of the exine: Type 1, tectate-perforate, baculate, in sect. Helicteres; Type 11, tectate-perforate, psilate to weakly verrucate, in 4 species of sect. Orthocarpaea; Type 111, tectate-perforate, with the equatorial zone verrucate and the poles psilate, in sect. Stegogamos; Type IV, microreticulate, verrucate, in sect. Polyandria; Type V, tectate, scabrate, verrucate, in sect. Alicteres; Type VI, tectate-perforate, verrucate, in 2 species of sect. Orthocarpaeaand 4 species of sect. Orthothecium; Type VII, tectate-perforatefossulate, verrucate, the verrucae large, irregular in outline, often anastomosed, in 3 species of sect. Orthothecium; Type VIII, tectate to tectate-perforate-fossulate, perforations and fossulae as well as micro-verrugae and micro-echinae densely concentrated at the poles, the equatorial zone psilate or scabrate, in 3 species of sect. Orthothecium; Type IX, tectateperforate- fossulate, microechinate, the perforations and fossulae densely concentrated at the poles, the micro-echinae distributed throughout the surface but hardly differentiated on the poles, in 16 species of sect. Sacarolha and 5 species of sect. Orthothecium. The pollen types are ordered according to the complexity of the exine; with the types with uniform sculpture considered simpler and the types with polar and equatorial zones differentiated considered complex. Keys to identify the nine pollen types of Helicteres and the pollen types of related genera are presented. According to pollen morphology Neoregnellia is closely connected with Helicteres; this genus shares the same pollen type, IX, with sect. Sacarolha and some species of sect. Orthothecium. The pollens of Kleinhovia and Helicteres have many characters in common (shape, size, apertures), the only difference being the microreticulate surface of the former; they are rather close to each other. Reevesia thyrsoidea, Veeresia clarkii and Ungeria floribunda stand apart from Helicteres in having 3-5 brevi-colp(or)ate and suprareticulate grains. The very distinctive pollen of Pterospermum acerifolium (Iarge size, spheroidal, echinate) supports its segregation from the tribe Helictereae. In Helicteres the different patterns of exine sculpture have taxonomic and phylogenetic value. In the first place, they allow the recognition of the 4 monospecific sections (Helicteres, Stegogamos, Alicteres and Polyandria) and at the same time they reveal the coherence of the genus, since the other 3 sections which have many species (Orthocarpaea, Orthothecium and Sacarolha) are connected with each other not only by exomorphological characters but also by pollen characters. In the second place, they provide bases for interpreting infra-generic relationships and the possible origin of the genus.Two possible evolutionary trends of exine sculpture, which are representated in two diagrams, are proposed. The first possibility starts with the Type VI; from this pollen type the evolutionary trend would have diverged in several directions. On one side, a line would lead toward increasing complexity of the exine that would end in Type VIII. This kind of pollen grain would have given rise to Type IX. On the other side, several divergent lines might have taken place; modifications in the exine sculpture would have led toward a progressive simplicity that would culminate in the absence of sculptural elements of Type 11. From this kind of pollen grain Type I might have evolved. The second possibility starts from Type 11; in this case the evolutionary trend of the exine would have gone in only one direction; the exine would have acquired more and more complexity, giving rise to pollen types connected with each other by transitional forms.</p>

scholarly journals Pollen grain size associated with pollinator feeding strategy

2020 ◽  
Vol 287 (1933) ◽  
pp. 20201191 ◽  
Author(s):  
Kai Hao ◽  
Zhi-Xi Tian ◽  
Zi-Chen Wang ◽  
Shuang-Quan Huang
Keyword(s):  
Grain Size ◽  
Feeding Strategy ◽  
Pollen Grains ◽  
Field Studies ◽  
Interspecific Variation ◽  
Pollen Grain ◽  
Pollen Foraging ◽  
Pollinator Behaviour ◽  
Trade Offs ◽  
Pollen Grain Size

Angiosperm pollen grain diameter varies greatly from a few microns to over 100, but the selective forces driving the interspecific variation in pollen size remain unclear. Although both pre- and post-pollination hypotheses have been proposed, empirical evidence remains scarce. Here we propose that visits by pollen-foraging pollinators have selected against large pollen grains. An association between pollinator behaviour and pollen grain size was confirmed by field studies of 80 flowering species in natural communities, showing that pollinators positively collected pollen in those species with relatively smaller pollen grains but rarely did so in species with larger ones. Allowing for the confounding effects of pollinator type, flower size or style length and pollen grain number, we found a significant effect of pollen-foraging behaviour on variation in pollen grain size, particularly in bee-pollinated plants. While these results suggest that many plant species whose pollen is collected or consumed by pollinators produce small pollen grains, it remains unclear whether pollen grain size is directly affected by pollinator foraging habit or indirectly mediated by pollen number trade-offs.

scholarly journals COLOUR IMAGE IN 2D AND 3D MICROSCOPY FOR THE AUTOMATION OF POLLEN RATE MEASUREMENT

2011 ◽  
Vol 21 (1) ◽  
pp. 25 ◽  
Author(s):  
Pierre Bonton ◽  
Alain Boucher ◽  
Monique Thonnat ◽  
Regis Tomczak ◽  
Pablo J Hidalgo ◽  
...  
Keyword(s):  
Pollen Grains ◽  
Pollen Grain ◽  
Pollen Monitoring ◽  
3D Images ◽  
Pollen Dispersion ◽  
Colour Image ◽  
Pollen Types ◽  
2D And 3D ◽  
Prevention Of Allergy ◽  
Original Device

Pollen monitoring is of great importance for the prevention of allergy. As this activity is still largely carried out by humans, there is an increasing interest in the automation of pollen monitoring. The goal is to reduce monitoring time in order to plan more efficient treatments. In this context, an original device based on computer vision is developed. The goal of such a system is to provide accurate measurement of pollen concentration. This information can be used as well by palynologists, clinicians or by a forecast system to predict pollen dispersion. The system is composed of two modules: pollen grain extraction and pollen grain recognition. In the first module, the pollen grains are observed in light microscopy and are extracted automatically from a microscopic slide dyed with fuchsin and digitised in 3D. The colour segmentation techniques implemented on a hardware architecture are presented. In the second module, the pollen grains are analysed for recognition. To accomplish recognition, it is necessary to work on 3D images and to use deep palynological knowledge. This knowledge describes the pollen types according to their main visible characteristerics and to those which are important for recognition. Some pollen structures are identified, like the pore with annulus in Poaceae, the reticulum in Olea and similar pollen types or the cytoplasm in Cupressaceae. Preliminary results show correct recognition of some pollen types, like Urticaceae or Poaceae, and some groups of pollen types, like reticulate group.

Some observations on methods of estimating the proportions of morphologically similar pollen types in fossil samples

1982 ◽  
Vol 60 (10) ◽  
pp. 1888-1894 ◽  
Author(s):  
A. D. Gordon
Keyword(s):  
Maximum Likelihood ◽  
Numerical Methods ◽  
Late Quaternary ◽  
Pollen Grains ◽  
Morphological Characters ◽  
Pollen Grain ◽  
Eastern North America ◽  
Maximum Likelihood Approach ◽  
Pollen Types ◽  
Likelihood Approach

For pollen types whose morphological characters overlap markedly, it is often helpful to be able to estimate the proportions of each type present in a sample of pollen grains. Several numerical methods of estimation have been proposed in recent years. This paper criticizes some procedures that are based on the identification of each pollen grain, rather than the direct estimation of proportions. A class of maximum likelihood models is described and illustrated by the analysis of eight samples of Picea pollen from late Quaternary profiles in eastern North America. The maximum likelihood approach provides an indication of the precision of the estimates, a point considered to be important.

scholarly journals Image analysis in automatic system of pollen recognition

2012 ◽  
Vol 59 (1) ◽  
pp. 385-393 ◽  
Author(s):  
Piotr Rapiejko ◽  
Zbigniew M. Wawrzyniak ◽  
Ryszard S. Jachowicz ◽  
Dariusz Jurkiewicz
Keyword(s):  
Feature Vector ◽  
Pollen Grains ◽  
Ccd Camera ◽  
Feature Space ◽  
Pollen Grain ◽  
Low Level ◽  
Estimated Parameters ◽  
Fast Recognition ◽  
Pollen Types ◽  
Dimension Space

In allergology practice and research, it would be convenient to receive pollen identification and monitoring results in much shorter time than it comes from human identification. Image based analysis is one of the approaches to an automated identification scheme for pollen grain and pattern recognition on such images is widely used as a powerful tool. The goal of such attempt is to provide accurate, fast recognition and classification and counting of pollen grains by computer system for monitoring. The isolated pollen grain are objects extracted from microscopic image by CCD camera and PC computer under proper conditions for further analysis. The algorithms are based on the knowledge from feature vector analysis of estimated parameters calculated from grain characteristics, including morphological features, surface features and other applicable estimated characteristics. Segmentation algorithms specially tailored to pollen object characteristics provide exact descriptions of pollen characteristics (border and internal features) already used by human expert. The specific characteristics and its measures are statistically estimated for each object. Some low level statistics for estimated local and global measures of the features establish the feature space. Some special care should be paid on choosing these feature and on constructing the feature space to optimize the number of subspaces for higher recognition rates in low-level classification for type differentiation of pollen grains.The results of estimated parameters of feature vector in low dimension space for some typical pollen types are presented, as well as some effective and fast recognition results of performed experiments for different pollens. The findings show the ewidence of using proper chosen estimators of central and invariant moments (M21, NM2, NM3, NM8 NM9), of tailored characteristics for good enough classification measures (efficiency > 95%), even for low dimensional classifiers (≥ 3) for type differentiation of pollens grain.

scholarly journals Mapping the adaptive landscape of a major agricultural pathogen reveals evolutionary constraints across heterogeneous environments

2021 ◽  
Author(s):  
Anik Dutta ◽  
Fanny E. Hartmann ◽  
Carolina Sardinha Francisco ◽  
Bruce A. McDonald ◽  
Daniel Croll
Keyword(s):  
Life History ◽  
Large Scale ◽  
Life History Traits ◽  
Genetic Correlations ◽  
Stress Factors ◽  
Life History Trait ◽  
Adaptive Landscape ◽  
Heterogeneous Environments ◽  
Growth Responses ◽  
Trade Offs

AbstractThe adaptive potential of pathogens in novel or heterogeneous environments underpins the risk of disease epidemics. Antagonistic pleiotropy or differential resource allocation among life-history traits can constrain pathogen adaptation. However, we lack understanding of how the genetic architecture of individual traits can generate trade-offs. Here, we report a large-scale study based on 145 global strains of the fungal wheat pathogen Zymoseptoria tritici from four continents. We measured 50 life-history traits, including virulence and reproduction on 12 different wheat hosts and growth responses to several abiotic stressors. To elucidate the genetic basis of adaptation, we used genome-wide association mapping coupled with genetic correlation analyses. We show that most traits are governed by polygenic architectures and are highly heritable suggesting that adaptation proceeds mainly through allele frequency shifts at many loci. We identified negative genetic correlations among traits related to host colonization and survival in stressful environments. Such genetic constraints indicate that pleiotropic effects could limit the pathogen’s ability to cause host damage. In contrast, adaptation to abiotic stress factors was likely facilitated by synergistic pleiotropy. Our study illustrates how comprehensive mapping of life-history trait architectures across diverse environments allows to predict evolutionary trajectories of pathogens confronted with environmental perturbations.

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