scholarly journals Morphological diversity of pollen from selected species of the genus Taraxacum, according to their ploidal level

2012 ◽  
Vol 61 (1) ◽  
pp. 65-69 ◽  
Author(s):  
Jolanta Marciniuk ◽  
Anna Rudzińska-Langwald
Keyword(s):  
Pollen Grains ◽  
Morphological Diversity ◽  
Great Variability ◽  
2N Pollen ◽  
Regular Type ◽  
Unknown Number ◽  
Species Being ◽  
The Way

The study of the morphology of pollen concerned eight species of the genus <i>Taraxacum</i>. Seven types were chosen with a different number of chromosomes belonging to the section <i>Palustria</i>: <i>Taraxacum paucilobum</i> 2n = 3x = 24, <i>T. subdolum</i> 2n = 3x =24, <i>T. subpolonicum</i> 2n =3x = 24, <i>T. vindobonense</i> 2n = 4x = 32, <i>T. trilobifolium</i> 2n = 4x = 32, <i>T. mendax</i> 2n = 5x = 40, <i>T. portentosum</i> 2n =? and one type from the section <i>Obliqua</i> - <i>T. platyglossum</i> 2n =?. Pollen from all the examined species was observed by SEM microscopy. A distinct relation exists between the morphology of pollen and the way of reproduction. Pollen of triploidal species, being compulsory apomicts, is characterized by a great variability of the size and a high percentage of deformed pollen grains. Tetraploids, being optional apomicts, produce regular pollen with a relatively even size. The regular type of pollen in pentaploidal <i>Taraxacum mendax</i> and in species with an unknown number of chromosomes (<i>Taraxacum portentosum</i> and <i>T. platyglossum</i>) suggests that these taxa are optional apomicts.

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.

scholarly journals Pollen morphology of the genera Irlbachia, Tachia, Voyria and Voyriella (Gentianaceae Juss.) found in the Reserva Florestal Adolpho Ducke (Amazonas, Brazil)

2012 ◽  
Vol 26 (4) ◽  
pp. 916-923 ◽  
Author(s):  
Marcos Gonçalves Ferreira ◽  
Maria Lúcia Absy ◽  
Vânia Gonçalves-Esteves
Keyword(s):  
Pollen Morphology ◽  
Pollen Grains ◽  
Great Variability ◽  
Prolate Spheroidal ◽  
Morphology Study ◽  
Size And Shape ◽  
Oblate Spheroidal ◽  
Large Shape

A pollen morphology study of the Gentianaceae Juss. of Reserva Florestal Adolpho Ducke (Manaus, Brazil) was performed. The pollen grains of the studied species varied morphologically in their pollen units (tetrads or monads), size (small, medium and large), shape (oblate, suboblate, oblate spheroidal, spheroidal, prolate spheroidal and prolate), polarity (heteropolar, isopolar or subisopolar), symmetry (bilateral or radial) and number and type of aperture (3-colporate and 1-3porate). In relation to ornamentation, pollen grains had a sexine that was psilate in the Voyria species, microreticulate in Voyriella parviflora and reticulate heterobrochate in Tachia grandiflora and Irlbachia alata. The exine in I. alata showed great variability in the size and shape of the lumina, in addition to clavae of various sizes in the mesocolpium and apocolpium areas. In Tachia grandiflora, besides to long colpi, the heterobrochate exine demonstrated an increase in the lumina in the mesocolpium areas that decreased considerably in the apocolpium areas. In the species of Voyria, the pollen grains showed differences in shape, polarity and the number of apertures, which were spherical, isopolar and 3-porate in Voyria spruceana; prolate/oval, heteropolar and 1-porate in Voyria tenella; and oblate/elliptical (reniform), heteropolar and 2(3)-porate in Voyria aphylla and Voyria caerulea. The variations in pollen morphology and the peculiar characteristics of the genus suggest that Voyria should be treated as a unique taxon within Gentianaceae.

A comparison of progeny from diallel crosses of diploid potato with regard to the frequencies of 2n-pollen grains

Euphytica ◽  
1995 ◽  
Vol 92 (3) ◽  
pp. 313-320
Author(s):  
Qu Dongyu ◽  
Zhu Dewei ◽  
M. S. Ramanna ◽  
E. Jacobsen
Keyword(s):  
Pollen Grains ◽  
Diploid Potato ◽  
2N Pollen ◽  
Diallel Crosses

scholarly journals Colchicine did not affect the viability of induced 2n pollen in Populus tomentosa

Silva Fennica ◽  
2019 ◽  
Vol 53 (2) ◽  
Author(s):  
Yan Liu ◽  
Yuan Zhang ◽  
Qing Zhou ◽  
Jian Wu ◽  
Pingdong Zhang
Keyword(s):  
Pollen Germination ◽  
Pollen Viability ◽  
Pollen Grains ◽  
Populus Tomentosa ◽  
2N Pollen ◽  
Significant Difference ◽  
Diploid Pollen ◽  
Germination Experiments ◽  
Diploid Gametes

Colchicine is widely used as a mutagen to induce production of diploid gametes in plants. However, whether colchicine affects induced pollen viability remains unclear. To clarify whether colchicine affected the viability of induced pollen, we induced production of diploid pollen by colchicine, followed by pollen germination and crossing induced pollen with normal gametes to produce triploid in Carrière. The results showed that the predominant meiotic stages and the number of colchicine injections had significant effects on the occurrence rates of induced 2n pollen. When the colchicine injection was given at diakinesis, a significant decrease in the pollen production per bud was observed ( < 0.001). The morphology of the colchicine-induced 2n pollen was similar to that of the natural 2n pollen in its ectexine structure. The pollen germination experiments revealed that there was also no significant difference in germination rates between the induced diploid pollen and natural 2n pollen grains, and 68 triploids were created by crossing colchicine-induced pollen. Our findings revealed that colchicine injection could induce to produce 2n pollen and will not lead to dysfunction of induced diploid pollen.in vitroPopulus tomentosapP. tomentosa

Rythmes circannuels chez les mammifères hibernants sauvages

1985 ◽  
Vol 63 (3) ◽  
pp. 453-463 ◽  
Author(s):  
B. Canguilhem
Keyword(s):  
Circadian Rhythms ◽  
Great Variability ◽  
External Factors ◽  
Temperature Changes ◽  
Astronomical Time ◽  
Species Being ◽  
Species Ecology

Circannual rhythms have been studied for 25 years. Most information has come from work on hibernators. Like circadian rhythms, circannuals rhythms are endogenous, innate, self sustained, and their spontaneous frequencies (biological period) are always different from astronomical time. They are insensitive to temperature changes. Their mechanisms are not yet known. Circannual rhythms are synchronized by external factors. There is, however, a great variability among these rhythms, some species being better synchronized than others. Differences in species ecology could be involved in this variability. The adaptative value of these rhythms is discussed.

Anther culture of a 2n pollen producing clone of Solanum phureja Juz. &Buk.

1985 ◽  
Vol 27 (5) ◽  
pp. 559-564 ◽  
Author(s):  
R. E. Veilleux ◽  
J. Booze-Daniels ◽  
E. Pehu
Keyword(s):  
Anther Culture ◽  
Polyacrylamide Gel Electrophoresis ◽  
Pollen Grains ◽  
Unreduced Gametes ◽  
Solanum Phureja ◽  
2N Pollen ◽  
Regenerated Plants ◽  
Series Of Experiments ◽  
Pollen Formation ◽  
First And Second Generation

In a series of experiments, a total of 95 plants were regenerated from culture of 1416 anthers of a single genotype (PP5) of Solanum phureja that expressed a variable frequency of 2n pollen by the genetic equivalent of first division restitution. The regenerated plants included 29 monoploids (2n = x = 12), 58 diploids (2n = 2x = 24) and 8 tetraploids (2n = 4x = 48). Monoploids carrying the potential for 2n pollen formation are central to the development of a breeding scheme to construct highly heterozygous diplandroids. Segregation of tuber flesh color and tuber protein bands revealed by polyacrylamide gel electrophoresis in first and second generation anther-derived diploid plants provided evidence for both embryogenesis of 2n pollen as well as doubling of monoploid genomes as sources of anther-derived diploids. Because of variation for the same genetic markers in anther-derived tetraploids, sources other than embryogenesis of doubly restituted (4n) pollen grains were implied. An enhanced response to anther culture was noted in some anther-derived dihaploids.Key words: unreduced gametes, potato, anther culture, diplandroid, monoploid.

Cytological and histological studies on male and female gametophyte of endangered species Amygdalus nana in Slovakia

Biologia ◽  
2011 ◽  
Vol 66 (5) ◽  
Author(s):  
Renáta Chudíková ◽  
Ľuba Ďurišová ◽  
Tibor Baranec ◽  
Ivan Ikrényi
Keyword(s):  
Fruit Set ◽  
Abiotic Factors ◽  
Reproductive Potential ◽  
Pollen Grains ◽  
Reproductive Organs ◽  
Great Variability ◽  
Ornamental Plant ◽  
Natural Habitats ◽  
Male And Female ◽  
Female Reproductive Organs

AbstractAmygdalus nana L. (Dwarf Russian Almond) a well-known ornamental plant is endangered in its natural habitats on the territory of Slovakia. Using methods of cytology and embryology, the stages of reproductive cycle of the species were clarified. Especially the development of the male and female reproductive organs, processes of the fertilization and formation of the embryo were studied. The reduction of reproductive potential was caused by synergic influence of negative biotic and abiotic factors. Despite the presence of degenerated, misshapen pollen grains and a great variability in shape and size, a sufficient amount of normally developed viable pollen grains originated within the species Amygdalus nana. We did not observe serious disturbances during megasporogenesis and megagametogenesis, the reduction in fruit set was caused by the degeneration of ovules after unsuccessful pollination (unfavourable conditions during the flowering period) and after unsuccessful seed development, caused mainly by damages of reproductive organs by pests.

INTER-COMPATIBILITY AND PERFORMANCE OF DIPLOID AND DERIVED TETRAPLOID RAPE (BRASSICA CAMPESTRIS L.)

1962 ◽  
Vol 42 (4) ◽  
pp. 672-680 ◽  
Author(s):  
R. K. Downey ◽  
J. M. Armstrong
Keyword(s):  
Seed Oil ◽  
Brassica Campestris ◽  
Early Stage ◽  
Pollen Grains ◽  
2N Pollen ◽  
Seed Oil Content ◽  
Ploidy Levels ◽  
Good Penetration ◽  
Selection For ◽  
And Performance

Normal diploid and derived tetraploid strains of Brassica campestris were grown in alternate 6-row plots at two locations. Rows of tetraploid rape, spaced 18 inches from diploid rows, were distinctly reduced in yield of seed, oil content and seeds per pod, whereas the seed yield of the diploid was not affected by the proximity of the tetraploid. The yield of the tetraploid increased as the distance from the diploid plots increased.Pollen germination studies and controlled crosses were made within and between ploidy levels. Seven and one-half hours after pollination of 2n and 4n stigmas, n pollen had germinated and made good penetration into stylar tissue whereas pollen tubes were just emerging from 2n pollen grains. It was concluded that pollen from diploid plants had a competitive advantage over pollen from tetraploid plants.No evidence of mature triploid seeds was found on tetraploid plants exposed to n pollen or on diploid plants exposed to 2n pollen. It is suggested that if triploid embryos were formed they aborted at an early stage in development.Comparative yield of seed and oil at 13 locations showed that the derived tetraploid strains yielded less than diploid varieties. This was true despite six to eight generations of selection for seed and oil yield, following synthesis of the tetraploid, and although the strains were isolated in groups according to level of ploidy.

Taxonomy, palynology, and seed morphology of Paepalanthus decumbens, a new species of Eriocaulaceae from Minas Gerais, Brazil

2018 ◽  
Vol 151 (2) ◽  
pp. 252-261
Author(s):  
Marcelo Trovó ◽  
Wellerson L. Picanço ◽  
Vânia Gonçalves-Esteves
Keyword(s):  
New Species ◽  
Pollen Grains ◽  
Morphological Diversity ◽  
Minas Gerais ◽  
Seed Morphology ◽  
Morphological Description ◽  
Campos Rupestres ◽  
Floral Characters ◽  
First Time ◽  
A New Species

Background and aims – Paepalanthus is the largest genus of Neotropical Eriocaulaceae and the largest genus of Brazilian monocots. Much of its taxonomic and morphological diversity remains unknown. A new species is described, with details on pollen and seed morphology.Methods – The morphological description of the vegetative and floral characters was made using a stereoscopic microscope with camera. Pollen and seed samples from the new species and from two related taxa were studied under light microscopy and scanning electron microscopy.Key results – Paepalanthus decumbens is described and illustrated, including details of pollen grains and seeds. The species is restricted to a small area in the campos rupestres of Serra de São José (Minas Gerais, Brazil), and therefore should be considered as critically endangered. The decumbent stem, falciform leaves with long trichomes along the margins, the numerous and sericeous scapes of roughly the same size of the leaves, and the dark castaneous involucral bracts are useful features for the recognition of the new species. Paepalanthus decumbens is placed in P. subsect. Polyactis and compared with P. microphyllus and P. stannardii, which have their pollen grains and seeds also herein described for the first time.

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