Polymorphisme pollinique et polymorphisme génétique

1989 ◽  
Vol 67 (2) ◽  
pp. 538-543 ◽  
Author(s):  
I. Till ◽  
G. Valdeyron ◽  
P. H. Gouyon
Keyword(s):  
Key Words ◽  
Pollen Grains ◽  
Genetic Component ◽  
Key Words Polymorphism ◽  
Polymorphisme Génétique ◽  
Pollen Evolution ◽  
Pollen Polymorphism

The polymorphism of the exine of pollen grains was studied in different species to determine if it has a genetic component at the intraspecific level. For some species, the results show that significant differences exist between individuals and that the composition of populations can also vary. The authors conclude that the study of pollen polymorphism could increase our understanding of pollen evolution and the mechanisms of pollen – stigma interactions. Key words: polymorphism, pollen, ash, Rumex, iris.

scholarly journals Comparison of pollen morphological structures of some taxa belonging to Asparagus L. and Fritillaria L. (Liliaceae) from Turkey

1970 ◽  
Vol 36 (2) ◽  
pp. 111-120 ◽  
Author(s):  
H Ozler ◽  
S Pehlivan
Keyword(s):  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Key Words ◽  
Transmission Electron Microscope ◽  
Light Microscope ◽  
Pollen Morphology ◽  
Pollen Grains ◽  
Exine Sculpture ◽  
Transmission Electron ◽  
Scanning Electron

Pollen grains of 20 taxa from two genera of the Liliaceae were examined and compared by LM (light microscope), SEM (scanning electron microscope) and pollens of four taxa were also examined with TEM (transmission electron microscope). Pollen grains shed as monads. They are monosulcate and ellipsoidal. Fritillaria crassifolia subsp. crassifolia Freyn & Smt. sometimes sheds the pollen as dyads. Exine is semitectate and the tectum is perforate. Columellae are simplicolumellate. Ectexine is thicker than endexine. Exine sculpture (ornamentation) is reticulate, reticulate-rugulate, rugulate and retipilate in Asparagus pollens and reticulate, suprareticulate, rugulate-reticulate and striate-reticulate in Fritillaria pollens. Sulcus extends from distal to proximal in some pollens of Asparagus and Fritillaria.   Key words: Asparagus, Fritillaria, Liliaceae, Pollen morphology DOI = 10.3329/bjb.v36i2.1498 Bangladesh J. Bot. 36(2): 111-120, 2007 (December)

Genetic trends for weaning weight during development of a multibreed population of beef cattle in two contrasting environments

2000 ◽  
Vol 80 (1) ◽  
pp. 191-193
Author(s):  
J. J. Tosh ◽  
R. A. Kemp
Keyword(s):  
Natural Selection ◽  
Beef Cattle ◽  
Key Words ◽  
Genetic Component ◽  
Weaning Weight ◽  
Common Base ◽  
The Difference ◽  
Selection Differentials ◽  
Genetic Trends

Genetic trends for weaning weight were determined in two herds of multibreed beef cattle that originated from a common base and were subject to mutual breeding policies in separate environments. The herds diverged for the direct though not the maternal genetic component of weaning weight within the 13-yr period examined; in the final year, the difference (P < 0.001) between the herds was almost 3 kg. This could have been partly due to unequal selection differentials and generation intervals. Results suggested the extent of natural selection also differed between the two environments. Key words: Beef cattle, crossbreeding, genetic trends, selection, weaning weight

Development of wheat (Triticum aestivum) pollen wall before and after effect of a gametocide

1990 ◽  
Vol 68 (11) ◽  
pp. 2509-2516 ◽  
Author(s):  
Gamal A. El-Ghazaly ◽  
William A. Jensen
Keyword(s):  
Electron Microscopy ◽  
Triticum Aestivum ◽  
Key Words ◽  
Light And Electron Microscopy ◽  
Pollen Grains ◽  
Pollen Wall ◽  
Seed Plants ◽  
Before And After ◽  
After Effect

Light and electron microscopy studies show that pollen wall development in plants treated with the gametocide RH0007 and untreated plants was similar until the stage at which sporopollenin is normally deposited on the wall. At this stage, the pollen wall of treated plants is 80% thinner than that of the control. Shortly after this stage, the pollen grains in the treated plants collapse and abort. We conclude that the gametocide clearly acts through the inhibition of sporopollenin formation, which results in pollen death. As sporopollenin is found only in the pollen wall of seed plants and the spores of nonseed plants, harm to other parts of the plant is not expected to occur. Key words: pollen wall development, Triticum aestivum, gametocide.

scholarly journals Pollen morphology of some Turkish Campanula spp. and their taxonomic value

1970 ◽  
Vol 37 (1) ◽  
pp. 33-42 ◽  
Author(s):  
Ismuhan Potoglu Erkara ◽  
Atila Ocak ◽  
Sevil Pehlivan
Keyword(s):  
Key Words ◽  
Pollen Morphology ◽  
Pollen Grains ◽  
Exine Sculpture ◽  
Electron Microscopes ◽  
Scanning Electron Microscopes ◽  
First Time ◽  
Scanning Electron

Detailed pollen morphological structures of 12 Turkish species of Campanula L., e.g. C. argaea, C. cymbalaria, C. glomerata subsp. hispida, C. latiloba subsp. latiloba, C. lyrata subsp. lyrata, C. olympica, C. persicifolia, C. pterocaula, C. rapunculoides subsp. cordifolia, C. rapunculus var. rapunculus, C. stricta var. stricta, C. pamphylica subsp. tokurii have been studied under light (LM) and scanning electron microscopes (SEM) for the first time. LM and SEM investigations show that the pollen grains of 12 taxa are more or less oblato-sphaeroidal, triporate (and/or tetraporate), tectum-scabrate, or with circular amb. The exine sculpture is granulate-scabrate in C. argaea, C. lyrata subsp. lyrata, C. stricta var. stricta, C. glomerata subsp. hispida and C. pamphylica subsp. tokurii; but those of C. cymbalaria, C. latiloba subsp. latiloba, C. olympica, C. persicifolia, C. pterocaula, C. rapunculoides subsp. cordifolia and C. rapunculus var. rapunculus are rugulate-scabrate.   Key words: Campanula, Pollen grains, Pollen morphology doi:10.3329/bjb.v37i1.1561 Bangladesh J. Bot. 37(1): 33-42, 2008 (June)

scholarly journals Pollen morphology of some Allium L. (Lilliaceae) taxa in turkey

1970 ◽  
Vol 39 (1) ◽  
pp. 37-46 ◽  
Author(s):  
H Özler ◽  
S Pehlivan
Keyword(s):  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Key Words ◽  
Transmission Electron Microscope ◽  
Pollen Morphology ◽  
Pollen Grains ◽  
Exine Sculpture ◽  
Transmission Electron ◽  
Scanning Electron

Pollen grains of 16 taxa of Allium L. belonging to sections Rhizirideum G. Don ex Koch., Codonoprasum Reichb. and Allium L. were investigated using light and scanning electron microscope, and pollens of four taxa were also examined with transmission electron microscope. Pollens were monosulcate and ellipsoidal. It was observed that the sulcus extends from distal to proximal in all taxa. The exine was semitectate and the tectum was perforate. Columellae were simplicolumellate. Exine sculpture was striate-perforate, striate-rugulate-perforate and rugulate-perforate. A. albidum Fischer ex Bieb. subsp. caucasicum (Regel) Stearn, A. rupicola Boiss ex Mouterde and A. asperiflorum Miscz. were seen to have an operculum. Key words: Allium; Codonoprasum; Rhizirideum; Alliaceae; Pollen morphology; Turkey DOI: 10.3329/bjb.v39i1.5524Bangladesh J. Bot. 39(1): 37-36, 2010 (June)

Pollen morphology of Lagotis (Scrophulariaceae)

1995 ◽  
Vol 73 (5) ◽  
pp. 701-709 ◽  
Author(s):  
Charles L. Argue
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Light Microscopy ◽  
Key Words ◽  
Pollen Morphology ◽  
Pollen Grains ◽  
As Species ◽  
Close Relationship ◽  
Scanning Electron

The pollen grains of 18 species of Lagotis have been examined using light microscopy and scanning electron microscopy of whole and fractured pollen. The grains are characterized by tricolporate apertures with smooth to sparsely granular ectocolpus membranes; lolongate endoapertures with unthickened margins included within the ectocolpi; relatively large exinous processes over the endoaperture; and columellate, semitectate, reticulate to microreticulate exines with or without supramurial processes. Lumina are reduced in size toward the colpus, but the transition is gradual, and a sharply bounded, differentially sculptured colpus border is absent. Lagotis pollen is distinct from that of the Selagineae and Globularia and indistinct from that of some Veroniceae; however, the characters shared with the latter are of wide occurrence in the Scrophulariaceae. Pollen morphology supports the distinction between L. brachystachya and L. stolonifera. It is consistent with the postulated close relationship between L. micrantha and L. integra, and provides no evidence to support the reestablishment of L. cashmeriana, L. minor, L. pallasii, or L. kunawurensis as species distinct from L. glauca. Key words: pollen morphology, Lagotis, Globularia, Selagineae, Veroniceae.

Induction of bicellular pollen by trifluralin treatment and occurrence of triploids and aneuploids after fertilization in maize

Genome ◽  
1999 ◽  
Vol 42 (1) ◽  
pp. 154-157 ◽  
Author(s):  
Akio Kato
Keyword(s):  
Zea Mays ◽  
Effective Treatment ◽  
Key Words ◽  
Zea Mays L ◽  
Generative Cell ◽  
Pollen Grains ◽  
Aluminum Foil ◽  
Central Cell ◽  
Vegetative Nucleus ◽  
Chromosome Counts

By spraying tassels of maize (Zea mays L.) with a trifluralin solution before flowering, viable bicellular pollen grains (with one vegetative nucleus and one mitotically arrested diploid generative cell) were produced. Fertilization between a central cell (2n) of diploid plants and the mitotically arrested generative cell (2n) of the bicellular pollen induced by trifluralin treatment was detected by the presence of shriveled kernels on pollinated ears. A covered method (tassels covered with aluminum foil for 24 h after spraying) and a non-covered method were compared, and the non-covered treatment with 0.2-0.4% trefanocide solutions was the most effective treatment in producing viable bicellular pollen. About 40-50% of the kernels were shriveled on pollinated ears from the treatments. Chromosome counts on seedlings obtained from 0.3% non-covered treatment revealed 24% were triploid and 4% were aneuploid (2n = 19, 21, and 22).Key words: aneuploid, bicellular pollen, trifluralin, triploid, Zea mays L.

scholarly journals Airborne pollen grains at Chittagong University Campus, Bangladesh

1970 ◽  
Vol 38 (1) ◽  
pp. 39-46 ◽  
Author(s):  
MK Pasha ◽  
Mohammad Sohrab Hossain
Keyword(s):  
Key Words ◽  
Airborne Pollen ◽  
Cocos Nucifera ◽  
Pollen Grains ◽  
Pollen Concentration ◽  
University Campus ◽  
Artocarpus Heterophyllus ◽  
Maximum Contribution

A total of 4,549 airborne pollen grains were recorded and classified into 34 pollen morpho-types in an airborne pollen survey at Chittagong University campus, during October, 2006 to September 2007. Maximum contribution was made by Poaceae type (32.89%), followed by Cyperaceae (5.94%), Mesua nagassarium (3.98%), Amaranthaceae (3.72%), Mimosaceae (3.58%), Artocarpus heterophyllus (2.75%), Cocos nucifera (2.73%), Asteraceae (2.95%) and some other types specific to this region. The unidentified pollen contributed to an average of 16.90%. Maximum pollen concentration was observed in the month of March (20.27%) and minimum in July (2.70%). Key words: Airborne; Pollen grains; Palynology; Chittagong Univ. Campus; Bangladesh DOI: 10.3329/bjb.v38i1.5117 Bangladesh J. Bot. 38(1): 39-46, 2009 (June)

Ectopic formation of trichomes and stomata in floral organs of Arabidopsis thaliana induced by thidiazuron

1994 ◽  
Vol 72 (5) ◽  
pp. 671-677 ◽  
Author(s):  
S. P. Venglat ◽  
V. K. Sawhney
Keyword(s):  
Arabidopsis Thaliana ◽  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Key Words ◽  
Flower Development ◽  
Pollen Grains ◽  
Urea Derivative ◽  
Stages Of Development ◽  
Floral Organs ◽  
Scanning Electron

Thidiazuron (TDZ), a urea derivative, was applied to the inflorescences of Arabidopsis thaliana at early stages of development to study its effect on flower development. Scanning electron microscope observations revealed that TDZ induced the formation of branched trichomes on sepals and carpels and stomata on petals that are not normally produced on these organs. Concurrently, TDZ also suppressed the development of pollen grains in the anthers and ovules in the ovaries. In addition, TDZ induced an increase in the size of all the floral organs except stamens. These observations suggest that thidiazuron alters the differentiation processes in floral organs by inducing the production of traits that are characteristic of cauline leaves, i.e., trichomes and stomata. Key words: Arabidopsis thaliana, flower development, stomata, thidiazuron, trichomes.

The morphology and ultrastructure of Caytonanthus

1994 ◽  
Vol 72 (10) ◽  
pp. 1519-1527 ◽  
Author(s):  
Jeffrey M. Osborn
Keyword(s):  
Key Words ◽  
Middle Jurassic ◽  
Pollen Grains ◽  
Late Paleozoic ◽  
Character State ◽  
Phylogenetic Implications ◽  
Exine Ornamentation

The morphology and ultrastructure of Caytonanthus arberi pollen organs and pollen, collected from the Middle Jurassic, Cayton Bay locality of England, are described. Pollen organs consist of flattened rachises with suboppositely branched pinnae, which bear terminal synangia. The synangium is covered with a two-zoned (fibrillar and amorphous) cuticle. The locule of each pollen sac is lined with a lamellated tapetal membrane and contains numerous pollen grains and orbicules. Grains are small, monosulcate, and bisaccate. Exine ornamentation of the proximal wall is psilate, while distally the apertural membrane is scabrate. The exine is composed of a thick, lightly staining sexine and a thin, darkly staining nexine. The sexine is tectate-alveolate laterally, becoming nearly homogeneous medially. The infratectal alveolae are robust and are continuous with the endoreticular units of the sacci. Sacci are eusaccate, with endoreticulations attached only to the outer walls. Several immature grains have also been identified and indicate that the nexine is lamellate throughout and that infratectal alveolae and nexine lamellae are well developed prior to complete tectum synthesis. Saccus size and ultrastructure of Caytonanthus pollen are compared with those of other Late Paleozoic and Mesozoic seed ferns that produced saccate pollen (Callistophytales, Glossopteridales, Corystospermales) and found to be smaller and more extensively filled with thicker endoreticulations. Documentation of the eusaccate character state in Caytonanthus is also discussed regarding its phylogenetic implications. Key words: Caytonanthus, Caytoniales, Mesozoic, pollen, seed fern, ultrastructure.

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