2n pollen formation via parallel spindles in the potato cultivar sebago

1980 ◽  
Vol 57 (9) ◽  
pp. 449-455 ◽  
Author(s):  
E. W. Souter ◽  
J. C. Dawe ◽  
S. J. Peloquin
Keyword(s):  
Potato Cultivar ◽  
2N Pollen ◽  
Parallel Spindles ◽  
Pollen Formation

THREE MECHANISMS OF 2n POLLEN FORMATION IN DIPLOID POTATOES

1975 ◽  
Vol 17 (2) ◽  
pp. 217-225 ◽  
Author(s):  
D. W. S. Mok ◽  
S. J. Peloquin
Keyword(s):  
Meiotic Division ◽  
Genetic Data ◽  
The Other ◽  
Cleavage Furrow ◽  
2N Pollen ◽  
Parallel Spindles ◽  
Solatium Tuberosum ◽  
Pollen Formation ◽  
Group Tuberosum

Three mechanisms of 2n pollen formation observed in diploid hybrids between Solatium tuberosum Group Phureja (2x) and haploids of S. tuberosum Group Tuberosum (4x) are termed parallel spindles (ps), premature cytokinesis 1 (pc 1) and premature cytokinesis 2 (pc 2). A II spindles are parallel to each other in many cells of clones producing 2n pollen by ps. A single cleavage furrow follows and forms a dyad which generates two 2n microspores. The other two mechanisms, pc 1 and pc 2, produce 2n pollen by omission of the second meiotic division. Premature cytokinesis 1 (pc 1) involves asynchronized movement of bivalents to and from the M I plate and falling apart of chromatids at T I. A cleavage furrow follows the first meiotic division, no second division occurs and products of meiosis are dyads. Premature cytokinesis 2 (pc 2) exhibits no abnormalities at the first meiotic division. However, cytokinesis occurs prematurely at P II, no second division occurs, and only dyads are formed. Genetic data suggested that these three mechanisms may be controlled by single loci, and are inherited independently as simple recessives.

Cytological basis of 2n pollen formation in a wide range of 2x, 4x, and 6x taxa from tuber-bearing Solanum species

Genome ◽  
1993 ◽  
Vol 36 (1) ◽  
pp. 8-13 ◽  
Author(s):  
Kazuo Watanabe ◽  
Stanley J. Peloquin
Keyword(s):  
South America ◽  
Solanum Species ◽  
2N Pollen ◽  
Parallel Spindles ◽  
Wide Range ◽  
Pollen Formation

Cytological mechanisms of 2n pollen formation were investigated in microsporogenesis and sporad development in 2x, 4x, and 6x taxa of tuber-bearing Solanum species that were originally collected from Mexico, and Central and South America. Parallel spindles and tripoles were seen at anaphase II in the majority of genotypes observed. The occurrence of parallel spindles and tripoles were well correlated with the occurrence of dyads and triads at the sporad stage. Further, the frequency of 2n pollen predicted by frequencies of parallel spindles and tripoles and by frequencies of dyads and triads were also well correlated with observed 2n pollen frequencies. Premature cytokinesis at telophase I to prophase II was seen only in 2x and 4x species from series Conicibaccata. The frequency of premature cytokinesis corresponded well with the frequency of dyads leading to 2n pollen formation. It was concluded that the major mechanisms of 2n pollen formation in tuber-bearing Solanum species is parallel spindles.Key words: cytological mechanisms, parallel spindles, ploidy series, tuber-bearing Solanum species, 2n pollen.

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.

Cytological mechanisms of 2n pollen formation in the wild potato Solanum okadae and pollen-pistil relations with the cultivated potato, Solanum tuberosum

2007 ◽  
Vol 55 (3) ◽  
pp. 471-477 ◽  
Author(s):  
Elsa Lucila Camadro ◽  
Sandra Karina Saffarano ◽  
Juan Carlos Espinillo ◽  
Mateo Castro ◽  
Phillip W. Simon
Keyword(s):  
Solanum Tuberosum ◽  
Wild Potato ◽  
2N Pollen ◽  
Cultivated Potato ◽  
In The Wild ◽  
Pollen Formation

Cytological mechanism of 2n pollen formation and unilateral sexual polyploidization in Lolium

Euphytica ◽  
1989 ◽  
Vol 43 (1-2) ◽  
pp. 1-6 ◽  
Author(s):  
C. A. Sala ◽  
E. L. Camadro ◽  
M. T. Salaberry ◽  
A. O. Mendiburu
Keyword(s):  
2N Pollen ◽  
Sexual Polyploidization ◽  
Unilateral Sexual Polyploidization ◽  
Pollen Formation ◽  
Cytological Mechanism

Meiotic aberrations during 2n pollen formation in Begonia

Heredity ◽  
2009 ◽  
Vol 104 (2) ◽  
pp. 215-223 ◽  
Author(s):  
A Dewitte ◽  
T Eeckhaut ◽  
J Van Huylenbroeck ◽  
E Van Bockstaele
Keyword(s):  
2N Pollen ◽  
Pollen Formation ◽  
Meiotic Aberrations

scholarly journals Complete asynapsis resulting in 2n pollen formation in Paspalum jesuiticum Parodi (Poaceae)

2014 ◽  
Vol 13 (1) ◽  
pp. 255-261 ◽  
Author(s):  
R.A. Bernardo Filho ◽  
A.C.C. Santos ◽  
F.H.D. Souza ◽  
J.F.M. Valls ◽  
M.S. Pagliarini
Keyword(s):  
2N Pollen ◽  
Pollen Formation

Gene-centromere mapping in potato by half-tetrad analysis: map distances of H1, Rx, and Ry and their possible use for ascertaining the mode of 2n-pollen formation

Genome ◽  
1992 ◽  
Vol 35 (1) ◽  
pp. 1-7 ◽  
Author(s):  
Marinus Wagenvoort ◽  
Ewa Zimnoch-Guzowska
Keyword(s):  
Potato Virus ◽  
Potato Virus Y ◽  
Potato Virus X ◽  
2N Pollen ◽  
Tetrad Analysis ◽  
Extreme Resistance ◽  
Second Division Restitution ◽  
Pollen Formation ◽  
Tetraploid Progeny ◽  
Map Distance

Diploids from the tetraploid potato varieties 'Alcmaria' and 'Pansta' and from the tetraploid CPRO genotypes Y66-13-610 and Y66-13-636 were used in half-tetrad analyses to estimate the gene-centromere map distances of the genes Rx, Ry, and H1. Employing tetraploid progeny from 2x (second division restitution) – 4x testcrosses the gene-centromere map distance of H1, conferring resistance to pathotype Ro1 of Globodera rostochiensis, was estimated to be 16.3 centimorgans (cM). For Rχ, conferring extreme resistance to potato virus X (PVX), a map distance of 33.9 cM was estimated. The gene Ry, conferring extreme resistance to potato virus Y (PVY), was estimated to be located 14.2 cM from the centromere. Using the estimated map distance for Rx, it was attempted to determine the mode of 2n-pollen formation in four diploid interspecific hybrids, including the species Solanum tuberosum, Solanum chacoense, Solanum yungasense, and Solanum phureja, by half-tetrad analysis in tetraploid progeny from 4x-2x testcrosses. The mean frequency of 8.7% nulliplex plants for Rx was outside the range of the 95% confidence intervals, for both first division restitution and second division restitution 2n pollen.Key words: nematode resistance, potato virus X resistance, potato virus Y resistance, 2n eggs, gene-centromere mapping, Solanum.

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