Microstrobilate Morphology, Microsporogenesis, and Pollen Formation in Western Hemlock

1974 ◽  
Vol 4 (4) ◽  
pp. 509-517 ◽  
Author(s):  
Rong H. Ho ◽  
John N. Owens
Keyword(s):  
Low Temperatures ◽  
Pollen Development ◽  
Pollen Grains ◽  
Western Hemlock ◽  
Abaxial Surface ◽  
Chromosome Behavior ◽  
The Common ◽  
Pollen Formation ◽  
Prothallial Cell

In western hemlock (Tsugaheterophylla (Raf.) Sarg.), the number of microstrobili per shoot averages 4.2. Each microstrobilus averages 13.9 bud scales and 17.2 microsporophylls. Microsporangia have a transverse dehiscence layer on the abaxial surface. There are an average of 1476 pollen grains per microsporangium and 17.4 million pollen grains per gram.Meiosis begins in the fall but stops at pachytene in November; it resumes in the middle of February and is completed in 1 week. Three weeks after the completion of meiosis the first prothallial cell forms and two weeks later the pollen grains reach maturity. Pollen shedding occurs 1.5 months after the resumption of meiosis and lasts for 2 weeks. Chromosome behavior and pollen formation are normal in 98.4% of the cells and in 99.7% of the pollen grains. The common abnormalities encountered are chiasma bridges, precocious disjunction, lagging chromosomes, and undersized pollen grains. The abnormalities may be attributed to the low temperatures occurring during meiosis and pollen development.

Microsporogenesis and pollen formation in lodgepole pine

1974 ◽  
Vol 52 (7) ◽  
pp. 1669-1674 ◽  
Author(s):  
Rong H. Ho ◽  
John N. Owens
Keyword(s):  
Cell Wall ◽  
Low Temperatures ◽  
Pinus Contorta ◽  
Lodgepole Pine ◽  
Pollen Grains ◽  
Chromosome Movement ◽  
Cell Wall Formation ◽  
Chromosome Behavior ◽  
Pollen Formation ◽  
Mother Cells

Microsporogenesis and pollen formation of three coastal and two interior lodgepole pine (Pinus contorta Dougl.) trees, and microstrobili of the interior trees were studied. Microspore mother cells were at pachytene when first observed and they remained at pachytene until the end of March in the interior trees and until mid-April in the coastal trees. The stages from pachytene to pollen shedding took 1 month in the coastal and interior trees. Several abnormalities were found in chromosome behavior, cell wall formation, and pollen grains. The percentage of abnormalities was higher in the interior trees than in the coastal trees. Abnormalities in chromosome movement seem to be genetically influenced and may be attributed to the large chromosomes, and to the prolonged low temperatures during meiosis and pollen formation. For interior lodgepole pine, the average number of microstrobili per shoot is 19.6 with 8.3 bud scales per microstrobilus, 93.3 microsporophylls per microstrobilus, and 2491 pollen grains per microsporangium. It is estimated that each microstrobilus produces about 465 000 pollen grains and each shoot produces about 9 million. There are about 33.5 million pollen grains per gram of dry pollen in lodgepole pine.

Tapetum character states: analytical keys for tapetum types and activities

1997 ◽  
Vol 75 (9) ◽  
pp. 1448-1459 ◽  
Author(s):  
E. Pacini
Keyword(s):  
Pollen Development ◽  
Cell Walls ◽  
Pollen Grains ◽  
Cell Types ◽  
Plastid Differentiation ◽  
Pollen Coat ◽  
Tapetal Cells ◽  
Different Types ◽  
Compound Pollen ◽  
Pollen Formation

The different types of tapetum found in the spermatophyta are described, along with associated characters. The characters (taken singly, pairwise, or in multiple combinations) are (i) tapetum types; (ii) cell walls, tapetum types, and loculus; (iii) tapetal cells individually, tapetum types, and loculus; (iv) number of pollen grains enveloped by tapetal cells and type of pollen dispersing unit; (v) cell types and tapetum types; (vi) number of nuclei per cell and tapetum type; (vii) cycles of hyperactivity; (viii) exine formation; (ix) orbicles; (x) peritapetal membrane; (xi) plastid differentiation; (xii) stage of pollen development in which tapetal cells degenerate and type of pollen coat; (xiii) storage vacuoles; (xiv) sporophytic proteins; and (xv) devices of tapetal origin responsible for compound pollen formation and pollination. Examples are given and an analytical key of structural and functional diversity is provided as a helpful approach to the study of the tapetum. Key words: tapetum types, activities, pollen dispersing units.

scholarly journals A Novel R2R3-MYB Gene LoMYB33 From Lily Is Specifically Expressed in Anthers and Plays a Role in Pollen Development

2021 ◽  
Vol 12 ◽  
Author(s):  
Xinyue Liu ◽  
Ze Wu ◽  
Jingxian Feng ◽  
Guozhen Yuan ◽  
Ling He ◽  
...  
Keyword(s):  
Amino Acids ◽  
Transcriptional Activation ◽  
Pollen Development ◽  
Biotic Resistance ◽  
Pollen Grains ◽  
Anther Development ◽  
Transactivation Domain ◽  
Reading Frame ◽  
Pollen Formation ◽  
R2r3 Myb

Lily (Lilium spp.) is an important commercial flower crop, but its market popularity and applications are adversely affected by severe pollen pollution. Many studies have examined pollen development in model plants, but few studies have been conducted on flower crops such as lily. GAMYBs are a class of R2R3-MYB transcription factors and play important roles in plant development and biotic resistance; their functions vary in different pathways, and many of them are involved in anther development. However, their function and regulatory role in lily remain unclear. Here, the GAMYB homolog LoMYB33 was isolated and identified from lily. The open reading frame of LoMYB33 was 1620 bp and encoded a protein with 539 amino acids localized in the nucleus and cytoplasm. Protein sequence alignment showed that LoMYB33 contained a conserved R2R3 domain and three BOX motifs (BOX1, BOX2, and BOX3), which were unique to the GAMYB family. LoMYB33 had transcriptional activation activity, and its transactivation domain was located within 90 amino acids of the C-terminal. LoMYB33 was highly expressed during the late stages of anther development, especially in pollen. Analysis of the promoter activity of LoMYB33 in transgenic Arabidopsis revealed that the LoMYB33 promoter was highly activated in the pollen of stage 12 to 13 flowers. Overexpression of LoMYB33 in Arabidopsis significantly retarded growth; the excess accumulation of LoMYB33 also negatively affected normal anther development, which generated fewer pollen grains and resulted in partial male sterility in transgenic plants. Silencing of LoMYB33 in lily also greatly decreased the amount of pollen. Overall, our results suggested that LoMYB33 might play an important role in the anther development and pollen formation of lily.

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.

CYTOLOGY OF 2n POLLEN FORMATION IN DIPLOID ALFALFA, MEDICAGO SATIVA

1979 ◽  
Vol 21 (4) ◽  
pp. 525-530 ◽  
Author(s):  
Nicholi Vorsa ◽  
E. T. Bingham
Keyword(s):  
Medicago Sativa ◽  
Seed Set ◽  
Pollen Grains ◽  
Genetic Constitution ◽  
2N Pollen ◽  
Diploid Parent ◽  
2N Gamete ◽  
Medicago Sativa L ◽  
Pollen Formation ◽  
Mother Cells

Four diploid (2x) clones of alfalfa, Medicago sativa L., which produced good seed set when used as male parents in 4x-2x crosses were selected for study. The 2x clones descended from 2x haploids of cultivated 4x alfalfa. Fertility in the 4x-2x cross was due to the production of pollen with the unreduced chromosome number (2n pollen) from the 2x parent. The cytological mechanism of 2n pollen formation was found to be disorientation of spindles at metaphase II in up to 38% of the pollen mother cells. Thus, both n and 2n pollen were produced by all four diploids examined. Normal spindles at metaphase II were oriented such that they defined the poles of a tetrahedron and resulted in normal tetrads in a tetrahedral arrangement. Disoriented spindles were basically parallel to each other and resulted in formation of dyads and occasionally a triad. Dyads developed into two 2n pollen grains; triads developed into one 2n and two n pollen grains. Since both n and 2n pollen grains are produced by the diploids, they can be maintained as diploids or they can be used as male parents in crosses to tetraploids. The genetic constitution of 2n pollen resulting from parallel spindles is similar to that expected after first division restitution of meiosis and much of the heterozygosity of the diploid parent is conserved in the gametes. The 2n gamete mechanism has potential application in germplasm transfer and in maximizing heterozygosity in tetraploid hybrids.

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 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.

Perspectives of the advanced functional using of some ornamental bushy crops

2021 ◽  
pp. 212-222
Author(s):  
V.M. Yezhov ◽  
◽  
V.I. Dubrovskyi ◽  
O.Yu. Ansieiev ◽  
O.A. Olenich ◽  
...  
Keyword(s):  
Low Temperatures ◽  
Left Bank ◽  
New Variety ◽  
Common Lilac ◽  
Significant Yield ◽  
The Common ◽  
Ornamental Shrubs ◽  
The Rose ◽  
Selection Of

The authors present the results of the collection’s formation of some ornamental shrubs, long-term phenological observations of them and the selection of the best forms and breeding hybrids in the Left-Bank Lisosteppe of Ukraine. In particular, the characteristic of the vegetation of 20 varieties of common lilac collection is given. The estimation of the terms and duration of the crop flowering enable to divide its varieties into groups of early, average and late flowering. The high decorative value of most of the strains has been described as well as their resistance to low temperatures and pests. The additional analysis of the latest literature data has shown the significant yield of aromatic substances in the common lilac plant, with the predominance of alkanes and lilac alcohol. The results have been presented of 70 rose cultivars of adaptation to the growing zone conditions. There are 20 promise varieties of the crop, which are characterized by high decorative value, resistance to pathogens and low temperatures and duration of flowering. The characteristics of the new variety of roses of the floribunda group – Olexandra has been given created by the authors. Along side with the high decorative value, different types of the rose plant provide the significant yield of aromatic substances with the domination of alkanes, monoterpenes and 2-phenylethanol. The analysis of the literature data also has shown the presence of aromatic substances in the jasmine and mock-orange plants. The first is characterized with esters based on benzene, cis-jasmon and isophytol, the second – with some sesquiterpenes and epi-13-manol. The further research included the phenological evaluation of the of white cedar and juniper collection. The best selected forms were characterized with decorativeness, resistance to frost, pests and pathogens. The literature data have shown, that the aromatic complex of the crops cultures includes mainly monoterpenes and their derivatives – alcohols and ketones. As a result, it was concluded that it is necessary to expand research with ornamental bushy crops in the direction of evaluating of their aromatic properties.

scholarly journals Flowering dynamics and pollen production of Laburnum anagyroides Med. under the conditions of south-eastern Poland

2013 ◽  
Vol 57 (2) ◽  
pp. 103-115 ◽  
Author(s):  
Ernest Stawiarz ◽  
Anna Wróblewska
Keyword(s):  
Pollen Grains ◽  
Average Weight ◽  
Pollen Production ◽  
Full Bloom ◽  
Flowering Duration ◽  
The Third ◽  
Laburnum Anagyroides ◽  
Golden Yellow ◽  
Single Flower ◽  
The Common

Abstract A study on the flowering biology and pollen production of the common laburnum (Laburnum anagyroides Med.) was conducted under the conditions of Lublin during the period 2004 - 2006. The flowering of this species began in the second 10-day period of May and lasted for 2.5 - 4 weeks. The flowers of common laburnum are borne in showy golden-yellow pendulous racemes. They develop successively, starting from the base and moving to the tip of an inflorescence. During the growing season, one shrub produces 800 to 3200 racemes, with 14 to 35 flowers in a single raceme. On average, the flowering duration for a raceme was 12.8 days and 8.7 days for a single flower. Throughout the study years, the shrubs proved to be most attractive in the third 10-day period of May when they reached full bloom. The average weight of pollen produced was 6.08 mg per 10 flowers of Laburnum anagyroides, 14.02 mg per raceme, and 26.0 g per shrub. Pollen grains reached average dimensions of 24.01 μm × 24.26 μm.

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.

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