scholarly journals Ultrastructural study of the relationship between generative and vegetative cells inMagnolia �soulangeana Soul.-Bod. pollen grains

PROTOPLASMA ◽  
1999 ◽  
Vol 206 (1-3) ◽  
pp. 87-96 ◽  
Author(s):  
A. M. Dinis ◽  
J. F. Mesquita
Keyword(s):  
Ultrastructural Study ◽  
Pollen Grains ◽  
Vegetative Cells ◽  
The Relationship

scholarly journals On the Relationship between Pollen Size and Genome Size

2010 ◽  
Vol 2010 ◽  
pp. 1-7 ◽  
Author(s):  
Charles A. Knight ◽  
Rachel B. Clancy ◽  
Lars Götzenberger ◽  
Leighton Dann ◽  
Jeremy M. Beaulieu
Keyword(s):  
Genome Size ◽  
Pollen Grains ◽  
Positive Contrast ◽  
Pollen Size ◽  
Positive Trend ◽  
Independent Contrasts ◽  
Regression Analyses ◽  
Significant Positive Trend ◽  
The Relationship ◽  
Published Research

Here we test whether genome size is a predictor of pollen size. If it were, inferences of ancient genome size would be possible using the abundant paleo-palynolgical record. We performed regression analyses across 464 species of pollen width and genome size. We found a significant positive trend. However, regression analysis using phylogentically independent contrasts did not support the correlated evolution of these traits. Instead, a large split between angiosperms and gymnosperms for both pollen width and genome size was revealed. Sister taxa were not more likely to show a positive contrast when compared to deeper nodes. However, significantly more congeneric species had a positive trend than expected by chance. These results may reflect the strong selection pressure for pollen to be small. Also, because pollen grains are not metabolically active when measured, their biology is different than other cells which have been shown to be strongly related to genome size, such as guard cells. Our findings contrast with previously published research. It was our hope that pollen size could be used as a proxy for inferring the genome size of ancient species. However, our results suggest pollen is not a good candidate for such endeavors.

Electrorotation of Isolated Generative and Vegetative Cells, and of Intact Pollen Grains of Lilium longiflorum

1998 ◽  
Vol 161 (1) ◽  
pp. 21-32 ◽  
Author(s):  
V.L. Sukhorukov ◽  
R. Benkert ◽  
G. Obermeyer ◽  
F.-W. Bentrup ◽  
U. Zimmermann
Keyword(s):  
Pollen Grains ◽  
Lilium Longiflorum ◽  
Vegetative Cells

scholarly journals Sensitivity of commercial pumpkin yield to potential decline among different groups of pollinating bees

2017 ◽  
Vol 4 (5) ◽  
pp. 170102 ◽  
Author(s):  
Sonja C. Pfister ◽  
Philipp W. Eckerter ◽  
Jens Schirmel ◽  
James E. Cresswell ◽  
Martin H. Entling
Keyword(s):  
Crop Yield ◽  
Fruit Set ◽  
Pollen Grains ◽  
Pollen Deposition ◽  
Insect Pollination ◽  
Study Region ◽  
Flower Visitation ◽  
Pollen Receipt ◽  
The Relationship ◽  
Pollinator Fauna

The yield of animal-pollinated crops is threatened by bee declines, but its precise sensitivity is poorly known. We therefore determined the yield dependence of Hokkaido pumpkin in Germany on insect pollination by quantifying: (i) the relationship between pollen receipt and fruit set and (ii) the cumulative pollen deposition of each pollinator group. We found that approximately 2500 pollen grains per flower were needed to maximize fruit set. At the measured rates of flower visitation, we estimated that bumblebees (21 visits/flower lifetime, 864 grains/visit) or honeybees (123 visits, 260 grains) could individually achieve maximum crop yield, whereas halictid bees are ineffective (11 visits, 16 grains). The pollinator fauna was capable of delivering 20 times the necessary amount of pollen. We therefore estimate that pumpkin yield was not pollination-limited in our study region and that it is currently fairly resilient to single declines of honeybees or wild bumblebees.

scholarly journals Subpollen particles (SPP) of birch as carriers of ice nucleating macromolecules

2021 ◽  
Author(s):  
Julia Burkart ◽  
Jürgen Gratzl ◽  
Teresa M. Seifried ◽  
Paul Bieber ◽  
Hinrich Grothe
Keyword(s):  
Protein Concentration ◽  
Birch Pollen ◽  
Pollen Grains ◽  
Ice Nucleation ◽  
Cloud Formation ◽  
Ultrapure Water ◽  
Fluorescence Excitation ◽  
Nucleation Activity ◽  
Ice Nucleation Activity ◽  
The Relationship

Abstract. Within the last years pollen grains have gained increasing attention due to their cloud forming potential. Especially the discovery that ice nucleating macromolecules (INM) or subpollen particles (SPP) obtained from pollen grains are able to initiate freezing has stirred up interest in pollen. INM or SPP are much smaller and potentially more numerous than pollen grains and could significantly affect cloud formation in the atmosphere. However, INM and SPP are not clearly distinguished and explanations on how these materials could distribute in the atmosphere are missing. In this study we focus on birch pollen and investigate the relationship between pollen grains, INM and SPP. According to the usage of the term SPP in the medical fields we define SPP as the starch granules contained in pollen grains. We develop an extraction method to generate large quantities of SPP and show that INM are loosley attached to SPP. Further, we find that purified SPP are not ice nucleation active: after several times of washing SPP with ultrapure water the ice nucleation activity completely disappears. To our knowledge this is the first study to investigate the ice nucleation activity of isolated SPP. To study the chemical nature of the INM we use fluorescence spectroscopy. Fluorescence excitation-emission maps indicate a strong signal in the protein range (maximum around λex = 280 nm and λem = 330 nm) that correlates with the ice nucleation activity. In contrast, with purified SPP this signal is lost. We also quantify the protein concentration with the Bradford assay. The protein concentration ranges from 77.4 μg mL−1 (Highly concentrated INM) to below 2.5 μg mL−1 (purified SPP). The results indicate a linkage between ice nucleation activity and protein concentration. Even though purified SPP are not ice nucleation active they could act as carriers of INM and distribute those in the atmosphere.

scholarly journals Palynological analysis of genus Geranium (Geraniaceae) and its systematic implications using scanning electron microscopy

Caryologia ◽  
2021 ◽  
Vol 74 (3) ◽  
pp. 31-43
Author(s):  
Jun Wang ◽  
Qiang Ye ◽  
Tong Zhang ◽  
Xusheng Shi ◽  
Majid Khayatnezhad ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Pollen Grains ◽  
Prolate Spheroid ◽  
Multivariate Statistical ◽  
Pollen Characters ◽  
Pollen Types ◽  
Ward Clustering ◽  
The Relationship ◽  
Scanning Electron

Pollen morphology of 23 species belonging to Geranium have been studied in details, which represent eight sections of two subgenera i.e., G. sect. Dissecta, Geranium, and Tuberosa of subgen. Geranium, Divaricata, Lucida, Ruberta and Trilopha of subgen. Robertium. These plant species were collected from different phytogeographical regions of Iran. The palynological investigation was done using scanning electron microscopy (SEM) techniques. Different palyno-morphological features have been observed, and the closely related species were distinguished. We used different multivariate statistical methods to reveal the species relationships. Ward clustering analyses have been done to check out the relationship among the species. The shapes of pollen grains were monad, radially symmetric, isopolar, apertures were tricolporate, and of spheroid, prolate-spheroid or sub-prolate classes. Three pollen types were recognized on the basis of differences in exine sculpturing pattern: reticulate-clavate, striate-rugulate, reticulum cristatum with clavae. Observed differences were not of diagnostic importance in subgenera and sections level. The main objective of this study is to find distinguish pollen characters in the species of the genus Geranium and to elucidate their systematics importance.

scholarly journals Pollen Release Dynamics and Daily Patterns of Pollen-Collecting Activity of Honeybee Apis mellifera and Bumblebee Bombus lantschouensis in Solar Greenhouse

Insects ◽  
2019 ◽  
Vol 10 (7) ◽  
pp. 216 ◽  
Author(s):  
Hong Zhang ◽  
Zhiyong Zhou ◽  
Jiandong An
Keyword(s):  
Apis Mellifera ◽  
Foraging Behaviour ◽  
Pollen Grains ◽  
Colony Development ◽  
Anther Dehiscence ◽  
Solar Greenhouse ◽  
Bee Foraging ◽  
Pollen Release ◽  
Increasing Temperature ◽  
The Relationship

Pollen is important not only for pollination and fertilization of plants, but also for colony development of bee pollinators. Anther dehiscence determines the available pollen that can be collected by foragers. In China, honeybees and bumblebees are widely used as pollinators in solar greenhouse agriculture. To better understand the effect of solar greenhouse microclimates on pollen release and pollen-foraging behaviour, we observed the anther dehiscence dynamics and daily pollen-collecting activity of Apis mellifera and Bombus lantschouensis during peach anthesis in a solar greenhouse in Beijing. Microclimate factors had a significant effect on anther dehiscence and bee foraging behaviour. The proportion of dehisced anthers increased with increasing temperature and decreasing relative humidity and peaked from 11:00 h to 14:00 h, coinciding with the peak pollen-collecting activity of bees. On sunny days, most pollen grains were collected by the two pollinators within two hours after anther dehiscence, at which time the viability of pollen had not yet significantly decreased. Our study helps us to better understand the relationship between food resources and pollinator foraging behaviour and to make better use of bees for pollination in Chinese solar greenhouses.

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