scholarly journals CYTOHISTOLOGY OF A 2–2–4 TYPE SPORT IN BARTLETT PEAR (Pyrus Communis)

HortScience ◽  
1992 ◽  
Vol 27 (6) ◽  
pp. 626c-626
Author(s):  
Qiangsheng Wang ◽  
Yinping Shi ◽  
Qingrong Sun ◽  
Yongsheng Yin
Keyword(s):  
Shoot Apex ◽  
Pollen Development ◽  
Pollen Grains ◽  
Pyrus Communis ◽  
Mother Plant ◽  
Sporogenous Tissue ◽  
Pollen Types ◽  
Tissue Cells

In the 1980' s, a Bartlett pear giant fruit sport was found in Pingdu, Shandong. The characteristics of mutation are larger fruit, thicker branch, shorter internode and much more spur. By grafting propagation, the clones began to bear fruit in 1990, and maintain the characteristics of variable mother plant. From microspore formation to blossom and spreading pollen, the cytohistological observation of sport flowering organs indicates: in every phase of pollen development, the size of florets, anthers and pollen grains are similar to CK; their pollen types both belong to tricolporat, pollen grains are nearly equal in size. This indicates that sport sporogenous tissue do not mutate. The observation of shoot apex sections showes: for CK, the cells of three histogenic layers range regularly; the size of cells, nuclei, and nucleoli among LI, LII, LIII are similar. For sport, the cells of LI, LII are no difference from CK, but in LIII and inner tissue, cells, nuclei, nucleoli all become larger clearly. This indicates LIII had mutated. So this sport is a 2–2–4 type chimera.

Resolution of Channels in the Exine by Translocation of Colloidal Iron

1971 ◽  
Vol 29 ◽  
pp. 352-353
Author(s):  
John R. Rowley
Keyword(s):  
Phosphate Buffer ◽  
Pollen Development ◽  
Osmium Tetroxide ◽  
Pollen Grains ◽  
Deionized Water ◽  
Colloidal Iron ◽  
Fixed Material ◽  
Epilobium Angustifolium ◽  
Untreated Material ◽  
Microspore Mitosis

The morphology of the exine of many pollen grains, at the time of flowering, is such that one can suppose that transport of substances through the exine occurred during pollen development. Holes or channels, microscopic to submicroscopic, are described for a large number of grains. An inner part of the exine of Epilobium angustifolium L. and E. montanum L., which may be referred to as the endexine, has irregularly shaped channels early in pollen development although by microspore mitosis there is no indication of such channeling in chemically fixed material. The nucleus in microspores used in the experiment reported here was in prophase of microspore mitosis and the endexine, while lamellated in untreated grains, did not contain irregularly shaped channels. Untreated material from the same part of the inflorescence as iron treated stamens was examined following fixation with 0.1M glutaraldehyde in cacodylate-HCl buffer at pH 6.9 (315 milliosmoles) for 24 hrs, 4% formaldehyde in phosphate buffer at pH 7.2 (1,300 milliosmoles) for 12 hrs, 1% glutaraldehyde mixed with 0.1% osmium tetroxide for 20 min, osmium tetroxide in deionized water for 2 hrs and 1% glutaraldehyde mixed with 4% formaldehyde in 0.1M cacodylate-HCl buffer at pH 6.9 for two hrs.

Pollen Taphonomy in a Canyon Stream

1987 ◽  
Vol 28 (3) ◽  
pp. 393-406 ◽  
Author(s):  
Patricia L. Fall
Keyword(s):  
Surface Soil ◽  
Pollen Grains ◽  
Close Correlation ◽  
Soil Samples ◽  
Alluvial Deposits ◽  
Modern Pollen ◽  
Pollen Types ◽  
Pollen Rain ◽  
Arid Steppe ◽  
Turbulent Water

AbstractSurface soil samples from the forested Chuska Mountains to the arid steppe of the Chinle Valley, Northeastern Arizona, show close correlation between modern pollen rain and vegetation. In contrast, modern alluvium is dominated by Pinus pollen throughout the canyon; it reflects neither the surrounding floodplain nor plateau vegetation. Pollen in surface soils is deposited by wind; pollen grains in alluvium are deposited by a stream as sedimentary particles. Clay-size particles correlate significantly with Pinus, Quercus, and Populus pollen. These pollen types settle, as clay does, in slack water. Chenopodiaceae-Amaranthus, Artemisia, other Tubuliflorae, and indeterminate pollen types correlate with sand-size particles, and are deposited by more turbulent water. Fluctuating pollen frequencies in alluvial deposits are related to sedimentology and do not reflect the local or regional vegetation where the sediments were deposited. Alluvial pollen is unreliable for reconstruction of paleoenvironments.

Pollen development in maize plants subjected to molybdenum deficiency

1979 ◽  
Vol 57 (18) ◽  
pp. 1946-1950 ◽  
Author(s):  
S. C. Agarwala ◽  
C. Chatterjee ◽  
P. N. Sharma ◽  
C. P. Sharma ◽  
N. Nautiyal
Keyword(s):  
Acid Phosphatase ◽  
Pollen Development ◽  
Pollen Grains ◽  
Starch Phosphorylase ◽  
Maize Plants ◽  
Male Flowers

A reduction in the size of tassels, male flowers, and anthers resulted from molybdenum deficiency in maize. In molybdenum-deficient plants, anthesis was suppressed or delayed and the anthers had fewer and smaller pollen grains that lacked dense cytoplasmic contents, appeared shrivelled, and had poor viability. Because of molybdenum deficiency, there was a decrease in the activity of starch phosphorylase in mature and freshly shed pollen grains and decreases in the activities of invertase and acid phosphatase at all the five stages at which pollen grains were assayed for the enzymes. The activities of catalase and peroxidase were increased by molybdenum deficiency at all five stages and that of ribonuclease at four out of the five stages of pollen development.

scholarly journals Airborne pollen observations using a multi-wavelength Raman polarization lidar in Finland: characterization of pure pollen types

2020 ◽  
Author(s):  
Xiaoxia Shang ◽  
Elina Giannakaki ◽  
Stephanie Bohlmann ◽  
Maria Filioglou ◽  
Annika Saarto ◽  
...  
Keyword(s):  
Optical Properties ◽  
Airborne Pollen ◽  
Pollen Grains ◽  
Wavelength Dependence ◽  
Depolarization Ratio ◽  
Mean Values ◽  
Pollen Types ◽  
Pine Pollen ◽  
Significant Wavelength ◽  
532 Nm

Abstract. We present a novel algorithm for characterizing the optical properties of pure pollen particles, based on the depolarization values obtained in lidar measurements. The algorithm was first tested and validated through a simulator, and then applied to the lidar observations during a four-month pollen campaign from May to August 2016 at the European Aerosol Research Lidar Network (EARLINET) station in Kuopio (62°44′ N, 27°33′ E), in Eastern Finland. Twenty types of pollen were observed and identified from concurrent measurements with Burkard sampler; Birch (Betula), pine (Pinus), spruce (Picea) and nettle (Urtica) pollen were most abundant, contributing more than 90 % of total pollen load, regarding number concentrations. Mean values of lidar-derived optical properties in the pollen layer were retrieved for four intense pollination periods (IPPs). Lidar ratios at both 355 and 532 nm ranged from 55 to 70 sr for all pollen types, without significant wavelength-dependence. Enhanced depolarization ratio was found when there were pollen grains in the atmosphere, and even higher depolarization ratio (with mean values of 25 % or 14 %) was observed with presence of the more non-spherical spruce or pine pollen. The depolarization ratio at 532 nm of pure pollen particles was assessed, resulting to 24 ± 3 % and 36 ± 5 % for birch and pine pollen, respectively. Pollen optical properties at 1064 nm and 355 nm were also estimated. The backscatter-related Ångström exponent between 532 and 1064 nm was assessed as ~ 0.8 (~ 0.5) for pure birch (pine) pollen, thus the longer wavelength would be better choice to trace pollen in the air. The pollen depolarization ratio at 355 nm of 17 % and 30 % were found for birch and pine pollen, respectively. The depolarization values show a wavelength dependence for pollen. This can be the key parameter for pollen detection and characterization.

scholarly journals snRNP: Rich Nuclear Bodies inHyacinthus orientalisL. Microspores and Developing Pollen Cells

2009 ◽  
Vol 2009 ◽  
pp. 1-12 ◽  
Author(s):  
K. Zienkiewicz ◽  
E. Bednarska
Keyword(s):  
Pollen Development ◽  
Rna Synthesis ◽  
Generative Cell ◽  
Pollen Grains ◽  
Strong Relationship ◽  
Nuclear Bodies ◽  
Cajal Body ◽  
Sm Proteins ◽  
Hyacinthus Orientalis

The aim of the present work was the characterization of nuclear bodies in the microspore and developing pollen cells ofHyacinthus orientalisL.. The combination of Ag-NOR, immunofluorescence and immunogold techniques was used in this study. The obtained results showed the presence of highly agyrophylic extranucleolar bodies in microspore and developing pollen cells, which were finally identified as Cajal bodies. In all cases, a strong accumulation of snRNP-indicating molecules including TMG cap, Sm proteins and U2 snRNA, was observed in the examined nuclear bodies. In contrast to their number the size of the identified structures did not change significantly during pollen development. In the microspore and the vegetative cell of pollen grains CBs were more numerous than in the generative cell. At later stages of pollen development, a drastic decrease in CB number was observed and, just before anthesis, a complete lack of these structures was indicated in both pollen nuclei. On the basis of these results, as well as our previous studies, we postulate a strong relationship between Cajal body numbers and the levels of RNA synthesis and splicing machinery elements in microspore and developing pollen cells.

A study on the pollen morphology of the genus Combretum Loefl. and its taxonomic significance

2016 ◽  
Vol 6 (4) ◽  
pp. 131-142
Author(s):  
Gamal E. B. E.B. El Ghazali
Keyword(s):  
Pollen Grains ◽  
Polar View ◽  
Taxonomic Revision ◽  
Molecular Classification ◽  
Ecological Indicator ◽  
Wide Range ◽  
Pollen Types ◽  
Specific Variation ◽  
Palynological Study

Pollen grains of 92 species (from 99 collections) belonging to the genus Com-bretum (Combretaceae) were examined by Light Microscope (LM) and Scan-ning Electron Microscope (SEM). These species are representatives of vari-ous taxa outlined in the latest taxonomic revision of the genus. The genus belongs to a tropical or subtropical family, frequently encountered in various Quaternary deposits and acts as ecological indicator in various habitats. Pol-len grains of all members of the genus Combretum examined are hetero-colpate (with three simple apertures alternating with three composite ones) and exhibited wide range of inter-specific variation with respect to polar axes (P), Equatorial diameters (E), P/E ratios, shape classes, shape in polar view, costae pori, vestibula, protrusion of endoapertures and exine sculptur-ings. Species delimitation in these nine characters is tabulated. Four shape classes, eight exine sculpturings and seven pollen types were recognized. A key for identification to these pollen types is presented and the species in-cluded in each of these types are also outlined. Previous macro-morphological and molecular classification of the genus were discussed in the light of the present palynological study.

Sporoderm morphogenesis in Euphorbia obesa and Croton gratissimus

Bothalia ◽  
1983 ◽  
Vol 14 (3/4) ◽  
pp. 849-856 ◽  
Author(s):  
M. L. Frean
Keyword(s):  
Pollen Morphology ◽  
Pollen Grains ◽  
Physiological Adaptation ◽  
Structure Characteristic ◽  
Pollen Type ◽  
Electron Microscope Level ◽  
Pollen Characters ◽  
Pollen Types ◽  
Unisexual Flowers ◽  
Taxonomic Grouping

Pollen grains of the Euphorbiaceae show a number of pollen types which can be clearly distinguished. Generally different genera are characterized by a specific pollen type.  Euphorbia obesa Hook. f. and Croton gratissimus Burch, subsp.  subgratissimus (Prain) Burtt Davy, represent two genera within the Crotonoideae with different morphology, each type characteristic for the respective genus. Taxonomically, the genus Euphorbia with apetalous flowers consisting of a naked pistil surrounded by several staminate flowers within a cyathium, is considered more advanced than the genus  Croton. In  Croton the inflorescence is a raceme with unisexual flowers. The floral whorls of the male show numerous anthers and both calyx and a showy corolla are present. Both genera are insect pollinated. In both  Euphorbia obesa and  Croton gratissimus the pollen wall in section shows columellae, a structure characteristic of angiosperms. However the present ontogenetic studies show that the formation of the columellae differs entirely in the two pollen types. The final stratification of the wall as well as the morphology of the grains differ and evaluation of the exine structure indicates that phylogenetically Croton pollen shows more advanced characters than  Euphorbia — contradicting the floral phylogeny. This study conducted at light and electron microscope level compares the two pollen types morphologically and ontogenetically, concentrating mainly on the formation of the exine which is tectate-perforate in the prolate tricolpate grain of Euphorbia obesa and semi-tectate in the anaperturate, spheroidal grain of Croton gratissimus. The aim of the study was to evaluate the significance of pollen characters in taxonomic and phylogenetic relationships within the Euphorbiaceae. The differing pollen morphology which is related to the taxonomic grouping of tribes within the subfamily (Crotonoideae) emphasizes diversity, which may result from physiological adaptation. The study shows that the same functional end may well be achieved in different ways and this may be a factor underlying the diversity in the heterogeneous family Euphorbiaceae.

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.

scholarly journals Overexpression of Two CCCH-type Zinc-Finger Protein Genes Leads to Pollen Abortion in Brassica campestris ssp. chinensis

Genes ◽  
2020 ◽  
Vol 11 (11) ◽  
pp. 1287
Author(s):  
Liai Xu ◽  
Tingting Liu ◽  
Xingpeng Xiong ◽  
Weimiao Liu ◽  
Youjian Yu ◽  
...  
Keyword(s):  
Transgenic Plants ◽  
Zinc Finger ◽  
Pollen Development ◽  
Brassica Campestris ◽  
Zinc Finger Protein ◽  
Function Analysis ◽  
Pollen Grains ◽  
Functional Redundancy ◽  
Pollen Abortion ◽  
Finger Protein

The pollen grains produced by flowering plants are vital for sexual reproduction. Previous studies have shown that two CCCH-type zinc-finger protein genes in Brassica campestris, BcMF30a and BcMF30c, are involved in pollen development. Due to their possible functional redundancy, gain-of-function analysis is helpful to reveal their respective biological functions. Here, we found that the phenotypes of BcMF30a and BcMF30c overexpression transgenic plants driven by their native promoters were similar, suggesting their functional redundancy. The results showed that the vegetative growth was not affected in both transgenic plants, but male fertility was reduced. Further analysis found that the abortion of transgenic pollen was caused by the degradation of pollen contents from the late uninucleate microspore stage. Subcellular localization analysis demonstrated that BcMF30a and BcMF30c could localize in cytoplasmic foci. Combined with the studies of other CCCH-type genes, we speculated that the overexpression of these genes can induce the continuous assembly of abnormal cytoplasmic foci, thus resulting in defective plant growth and development, which, in this study, led to pollen abortion. Both the overexpression and knockout of BcMF30a and BcMF30c lead to abnormal pollen development, indicating that the appropriate expression levels of these two genes are critical for the maintenance of normal pollen development.

scholarly journals Promoted ABA Hydroxylation by Capsicum annuum CYP707As Overexpression Suppresses Pollen Maturation in Nicotiana tabacum

2020 ◽  
Vol 11 ◽  
Author(s):  
Hyun Min Kim ◽  
Se Hee Park ◽  
Sang Hoon Ma ◽  
Seo Young Park ◽  
Chul-Ho Yun ◽  
...  
Keyword(s):  
Capsicum Annuum ◽  
Pollen Development ◽  
Pollen Grains ◽  
Phenotypic Analysis ◽  
Seed Formation ◽  
Pollen Maturation ◽  
Aba Metabolism ◽  
Cytochrome P450 Genes ◽  
Response To Stress ◽  
Aba Biosynthesis

Abscisic acid (ABA) is a key signaling molecule that mediates plant response to stress. Increasing evidence indicates that ABA also regulates many aspects of plant development, such as seed germination, leaf development, and ripening. ABA metabolism, including ABA biosynthesis and degradation, is an essential aspect of ABA response in plants. In this study, we identified four cytochrome P450 genes (CaCYP707A1, 2, 3, and 4) that mediate ABA hydroxylation, which is required for ABA degradation in Capsicum annuum. We observed that CaCYP707A-mediated ABA hydroxylation promotes ABA degradation, leading to low levels of ABA and a dehydration phenotype in 35S:CaCYP707A plants. Importantly, seed formation was strongly inhibited in 35S:CaCYP707A plants, and a cross-pollination test suggested that the defect in seed formation is caused by improper pollen development. Phenotypic analysis showed that pollen maturation is suppressed in 35S:CaCYP707A1 plants. Consequently, most 35S:CaCYP707A1 pollen grains degenerated, unlike non-transgenic (NT) pollen, which developed into mature pollen grains. Together our results indicate that CaCYP707A mediates ABA hydroxylation and thereby influences pollen development, helping to elucidate the mechanism underlying ABA-regulated pollen development.

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