THE INHERITANCE OF 2n POLLEN FORMATION IN DIPLOID ALFALFA MEDICAGO SATIVA

1982 ◽  
Vol 24 (3) ◽  
pp. 315-323 ◽  
Author(s):  
T. J. McCoy
Keyword(s):  
Medicago Sativa ◽  
High Frequency ◽  
Seed Set ◽  
Single Gene ◽  
Recessive Gene ◽  
2N Pollen ◽  
Good Seed ◽  
Ploidy Levels ◽  
Pollen Formation ◽  
Diploid Level

The inheritance of 2n pollen formation was studied in two diploid clones of alfalfa, Medicago sativa L. The two clones consistently produced a high frequency of 2n pollen, and they also porduced good seed set when used as males in 4x-2x crosses due to the functioning of 2n(2x) pollen. For the inheritance study the two clones were crossed with diploid clones of cultivated alfalfa at the diploid level (CADL), and with several clones of diploid M. falcata. In segregating families, plants that produced a high frequency of 2n pollen were identified by good seed set when used as males in 4x-2x crosses, and/or by bimodal pollen sizes. Plants that produced 4% or more 2n pollen generally produced greater than one seed per pollination in 4x-2x crosses, and these plants were considered 2n pollen producers. Analysis of self, F1, F2 and backcross (BC) families indicated 2n pollen formation was controlled by a single recessive gene, designated rp (restitution pollen). An allelism test indicated 2n pollen formation was controlled by the same recessive gene in both clones. Although there was considerable variation in the frequency of 2n pollen in rp/rp plants grown in different environments, all rp/rp plants consistently produced a significant frequency of 2n pollen (greater than 4%). Simple genetic control of 2n pollen formation has important implications in the evolution of the genus Medicago. In addition, 2n pollen formation controlled by a single gene may have potential application in the breeding of highly heterozygous tetraploids and in the efficient transfer of germplasm across ploidy levels.

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 High frequency 2n pollen formation in black poplar (Populus nigra L.) induced by colchicine

2019 ◽  
Vol 47 (3) ◽  
Author(s):  
Wenting XU ◽  
Yan ZHANG ◽  
Liqin GUO ◽  
Jian ZHAO ◽  
Zunzheng WEI ◽  
...  
Keyword(s):  
High Frequency ◽  
Colchicine Treatment ◽  
Tree Breeding ◽  
Populus Nigra ◽  
Digital Object Identifier ◽  
2N Pollen ◽  
Digital Object ◽  
The World ◽  
Pollen Formation ◽  
First Time

Populus nigra L. is one of the most important male genetic donors in populus genetic improvement and tree breeding over the world. Many excellent Populus nigra clones are identified as triploids potentially obtaining by hybridization of 2n pollen and normal oogamete. This study revealed the cytological mechanism of 2n pollen formation in Populus nigra L. for the first time and concluded the best treated combination of colchicine treatment, which obtained 2n pollen with the highest rate reaching at 87.11% (even 100% 2n pollen in some floral buds) which made the polyploid hybridization utilizing 2n pollen in section Aigeiros possible.   ********* In press - Online First. Article has been peer reviewed, accepted for publication and published online without pagination. It will receive pagination when the issue will be ready for publishing as a complete number (Volume 47, Issue 3, 2019). The article is searchable and citable by Digital Object Identifier (DOI). DOI link will become active after the article will be included in the complete issue. *********

Interspecific Crossability of Nine Diploid Fragaria Species

HortScience ◽  
1998 ◽  
Vol 33 (3) ◽  
pp. 483b-483 ◽  
Author(s):  
Bob Bors ◽  
J. Alan Sullivan
Keyword(s):  
Seed Set ◽  
Fragaria Vesca ◽  
Good Seed ◽  
Cotyledon Stage ◽  
Hybrid Plants ◽  
Group A ◽  
Group B ◽  
Diploid Level ◽  
Interspecific Crossability ◽  
Genomic Similarity

As part of a wild species introgression program, Fragaria vesca, F. viridis, F. nubicola, F. nipponica, F. nilgerrensis, F. pentaphylla, F. gracilis, F. daltoniana, and F. iinumae were crossed in most combinations possible, the exceptions being F. daltoniana and F. iinumae, which produced only a few flowers each. Crosses with F. vesca as a female and either F. gracilis, F. nipponica, or F. iinumae as males produced good seed set, but seedlings died in the cotyledon stage in every case. No seed set occurred when F. iinumae was crossed with F. viridis or F. nubicola. F. pentaphylla, F. gracilis, and F. iinumae were observed to be self-incompatible while F. daltoniana was self-compatible. Three overlapping groups based on crossing data have emerged. Within the following groups, hybrid plants were obtained in all species combinations, although not necessarily for reciprocal combinations: Group A: F. vesca, F. viridis, F. nubicola, and F. pentaphylla. Group B: F. vesca, F. nilgerrensis, F. daltoniana, and F. pentaphylla. Group C: F. pentaphylla, F. gracilis, and F. nipponica. Fertile or semifertile diploid hybrids were obtained for all species combinations within group A indicating genomic similarity or that breeding at the diploid level could occur with these species. Fertility has not been determined for hybrids in groups B and C. It is interesting to note the presence of F. pentaphylla in all three groups, perhaps this species plays an important role in Fragaria evolution.

Environmental induction of high frequency 2n pollen formation in diploid Solanum

1983 ◽  
Vol 25 (6) ◽  
pp. 609-615 ◽  
Author(s):  
N. A. McHale
Keyword(s):  
High Frequency ◽  
The Other ◽  
Similar Response ◽  
2N Pollen ◽  
Flowering Period ◽  
Field Site ◽  
Phenotypic Stability ◽  
Mean Frequency ◽  
Environmental Induction ◽  
Pollen Formation

Ten genotypes of Solanum phureja Juz. and Buk. producing 2n pollen via fused (FS) and tripolar (TPS) spindles at the second meiotic division were grown in 2 consecutive years at a cool field site (E1, 8–22 °C) and in a warm greenhouse (E2, 14–40 °C) to examine environmental effects on mean frequency and phenotypic stability of 2n pollen production. Overall frequencies of big pollen (BP) and dyad formation were substantially higher in E1 in both years. The stable standard (154-1) gave almost complete expressions of dyads in E1, with no bud below 99%. Four other genotypes (413, 414, 416, 417) gave a similar response in E1, producing mean dyad frequencies between 93 and 99%, with no bud below 80%. The other four genotypes (420, 424, 427, 429) and the variable standard (127–14) produced higher dyad frequencies in E1 versus E2, but their phenotypes remained variable in E1, showing disparities up to 79% between buds of a single collection. The fidelity of stable and variable phenotypes in E1 was examined by scoring dyad frequencies in putatively stable (413, 414, 415, 416) versus variable (420, 424, 427, 127–14) genotypes at four dates spanning the flowering period in this environment. The four stable genotypes showed consistent expression of high dyad frequency (86–99%) at all four dates. In contrast, dyad frequencies of the variable genotypes were substantially lower and more variable between and within collections.

CYSTIC FIBROSIS OF THE PANCREAS

PEDIATRICS ◽  
1957 ◽  
Vol 19 (6) ◽  
pp. 1136-1138
Author(s):  
Paul A. di Sant'Agnese ◽  
Charles Upton Lowe
Keyword(s):  
Cystic Fibrosis ◽  
Clinical Evidence ◽  
Clinical Effect ◽  
Single Gene ◽  
Pancreatic Insufficiency ◽  
Recessive Gene ◽  
The United States ◽  
Live Births ◽  
Almost All ◽  
Very High

IN THE COURSE of a review of all features of the disease, the following points were particularly noteworthy: Incidence This disease accounts for almost all cases of pancreatic insufficiency in children. The incidence in the population of the United States is between 1 in 600 and 1 in 10,000 live births, with a probable average incidence of 1 in 2,500. There is no sex predominance. There is, however, a difference in racial predilection, being rarely seen in the Negro and never in Mongolians. It is a familial disease, displaying the characteristics of a mendelian recessive gene. This means that in an affected family the disease may occur in approximately 25% of the offspring, that both parents must be carriers of the trait and that two-thirds of the non-affected children are also carriers. Birth order has no effect on the inheritance of this disease. The fact that it is usually a lethal disease indicates that the mutation rate for this gene must be very high; the frequency of the single gene in the population has been calculated to be approximately 1 in 50. Pancreatic Insufficiency Clinical evidence of poor digestion and absorption of protein and fat is seen in the increased quantities of these substances in the feces, which causes the feces to be bulky, foul smelling, foamy and greasy. Another clinical effect of malabsorption is seen in the failure of the newborn infant with cystic fibrosis of the pancreas to regain birth weight in the first 10 days of life. In the absence of other evidence of disease, this is a sign suggestive of pancreatic failure.

scholarly journals Meiotic Chromosome Behavior and Capsule Setting in Doritaenopsis Hybrids

2008 ◽  
Vol 133 (1) ◽  
pp. 107-116 ◽  
Author(s):  
Pablo Bolaños-Villegas ◽  
Shih-Wen Chin ◽  
Fure-Chyi Chen
Keyword(s):  
Cell Division ◽  
Pollen Mother Cell ◽  
Chromosome Pairing ◽  
Chromosomal Aberrations ◽  
High Frequency ◽  
Mother Cell ◽  
Seed Set ◽  
Pollen Viability ◽  
High Pollen ◽  
Mother Cells

The development of new cultivars in Doritaenopsis Guillaum. & Lami orchids is often hindered by factors such as low seed count in hybrids. Cytological study may offer the ability to develop new hybrids by revealing cultivars with good chromosome pairing and high pollen viability, which are somewhat difficult to obtain under current breeding programs. Cross pollination, pollen viability, and chromosomal behavior during meiosis were analyzed to reveal the relation between seed fertility and capsule set in Doritaenopsis hybrids. The number of mature capsules harvested and their relative seed content were used as indices of crossing availability. The results of meiosis were evaluated according to pollen viability detected by fluorescein diacetate and quantification of sporad types by acid fuchsin staining. Chromosome number and pairing at meiosis were observed in root tips or in samples of pollen mother cells. A positive relation was found among high seed set, high frequency of viable tetrads, high degree of chromosome pairing, and low frequency of chromosomal aberrations such as inversions and translocations. On the basis of these factors, three types of hybrids could be distinguished. In type one hybrids, chromosomes paired as bivalents, pollen mother cells divided into tetrads, and capsule setting occurred after pollination of pollen acceptors. In type two hybrids, chromosomes remained mainly as univalents that developed into micromeiocytes, pollen mother cell division was disrupted, and seed recovery was low after pollination. Type three hybrids showed chromosomes paired mostly as multivalents, chromosome bridges, pollen mother cell division with massive failure, and little fertility. In Doritaenopsis orchids, high pollen viability and high fertility depends on a high frequency of normal tetrads, and low seed set in cross-pollination is predicted with micronuclei in the end products of meiosis. The occurrence of chromosomal aberrations may suggest a process of genome differentiation that could compromise breeding efforts if not taken into consideration.

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

SELECTION FOR SEED SET IN NONINBRED AND PARTLY INBRED POPULATIONS OF ALFALFA

1977 ◽  
Vol 57 (3) ◽  
pp. 873-881 ◽  
Author(s):  
R. MICHAUD ◽  
T. H. BUSBICE
Keyword(s):  
Medicago Sativa ◽  
Seed Set ◽  
Exponential Model ◽  
Seed Setting ◽  
Medicago Sativa L ◽  
Selection For ◽  
Inbred Populations ◽  
The Relationship ◽  
Advanced Generation ◽  
Coefficient Of Inbreeding

Alfalfa (Medicago sativa L.) is a highly heterozygous cross-pollinating species, and most breeding efforts have been conducted on noninbred populations. The purpose of this study was to determine whether greater breeding progress could be made by selecting within partly inbred populations rather than within noninbred ones. One hundred and twenty F1 (noninbred) and 120 S1 (partly inbred) plants that were issued from crossing and selfing four alfalfa clones were evaluated for self-fertility. The most self-fertile 10% of the plants from each family were selected in each population. The selected plants within each level of inbreeding were intercrossed to produce an advanced generation in which the effectiveness of the selection was evaluated. Selection increased both self- and cross-fertility in the advanced generation. Selection was more effective at the F1 level than at the S1 level. Fertility was reduced drastically by inbreeding. The average self-fertility of the S1’s was only about 7% of the cross-fertility of their parental clones. An exponential model was proposed to describe the relationship between seed setting and the coefficient of inbreeding in the developing zygote. This model explained 95% of the variation among 11 unselected populations having differing levels of inbreeding.

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