INTERSPECIFIC CROSSES INVOLVING ALFALFA. IV. Medicago glomerata × M. sativa with reference to M. prostrata

1968 ◽  
Vol 10 (3) ◽  
pp. 536-544 ◽  
Author(s):  
K. Lesins
Keyword(s):  
Chromosome Pairing ◽  
Seed Set ◽  
Interspecific Crosses ◽  
Good Seed ◽  
Chromosome Behavior ◽  
Separate Species ◽  
Meiotic Irregularities ◽  
Preferential Chromosome Pairing ◽  
Morphological Differences ◽  
Anthocyanin Production

A good seed set was obtained from crosses of Medicago glomerata Balb. with M. sativa L. There was no evidence of a preferential chromosome pairing effect on segregation for floral anthocyanin. From an analysis of different M. glomerata × M. sativa crosses four factors were found to be involved in anthocyanin production. About 90% of the cells showed normal chromosome behavior during meiosis. Taxonomically, M. glomerata stands somewhat apart from the M. sativa — falcata complex, as indicated by a lower seed set from intercrossed F1's, and by somewhat higher numbers of meiotic irregularities in the F1 plants. With these and other morphological differences M. glomerata is considered as a separate species. When hybridized with M. prostrata Jacq., M. glomerata responded in a similar manner to that of M. sativa. The weight of seeds produced by M. glomerata plants was approximately the same, whether fertilized by M. glomerata or by M. sativa pollen. There is a somewhat greater affinity between M. glomerata and M. prostrata than between M. sativa and M. prostrate; M. prostrata plants fertilized by M. glomerata pollen had better seed development than those fertilized by M. sativa.

scholarly journals Production of Interspecific Hybrids between Hexaploid Fragaria moschata and the diploid species F. nubicola and F. viridis.

HortScience ◽  
1996 ◽  
Vol 31 (4) ◽  
pp. 610b-610
Author(s):  
Robert H. Bors ◽  
J. Alan Sullivan
Keyword(s):  
Seed Germination ◽  
Ploidy Level ◽  
Interspecific Hybrids ◽  
Leaf Morphology ◽  
Seed Set ◽  
Embryo Rescue ◽  
Diploid Species ◽  
Interspecific Crosses ◽  
Good Seed ◽  
Poor Seed

Interspecific crosses with Fragaria moschata (6x) have been hampered by ploidy level differences, poor seed set, and extremely poor seed germination. Modification of pollination practices, embryo rescue, and use of several genotypes has allowed over 80 synthetic tetraploids to be created from 14 cross combinations. Germplasm for the experiment consisted of eight selections of F. moschata (6x), two of F. nubicola (2x), and two of F. viridis (2x). Both 2x × 6x and 6x × 2x crosses were performed. Initially, negligible seed set occurred on F. nubicola and F. viridis when multiple flowers per truss were pollinated. When only one cross was performed per truss, with other flowers removed, seed set was greatly enhanced. F. moschata was much more tolerant of multiple crosses per truss. The crossing combination of F. moschata × F. nubicola gave the worst seed production. Other species combinations were capable of producing good seed set with noticeable differences between individual selections. When achenes were halved, only 1% appeared normal, 2% were underdeveloped or shrunken, the remainder were empty. Many of the malformed and most of the normal embryos germinated using the cut achene method. Achenes were surface-sterilized, cut in half, and placed on MS media with activated charcoal (3g·L–1), sucrose (30g·L–1), and no hormones. Germination occurred only from achenes from fully ripened fruit. Viable hybrids were obtained from 2x × 6x as well as 6x × 2x crosses. Fragaria viridis–F. moschata hybrids closely resembled F. moschata while F. nubicola–F. moschata hybrids were more intermediate in leaf morphology.

Relationship in annual species of Medicago. II. Interspecific crosses between M. tornato (L.) Mill. and M. littoralis Rhode.

1965 ◽  
Vol 16 (1) ◽  
pp. 51 ◽  
Author(s):  
JP Simon
Keyword(s):  
Pollen Fertility ◽  
Structural Changes ◽  
Seed Set ◽  
Morphological Characteristics ◽  
Pollen Sterility ◽  
Interspecific Crosses ◽  
Annual Species ◽  
Reciprocal Crosses ◽  
Meiotic Irregularities ◽  
Early Seedling

Six hybrids were obtained from 212 reciprocal crosses between M. littoralis Rhode and M. tornata (L.) Mill. The hybrids were chlorophyll-deficient in the early seedling stage but later development was normal although growth was retarded. The morphological characteristics were intermediate between those of the parents. Pollen fertility and seed set amounted to 7 and 10% respectively. Meiotic irregularities indicate that M. littoralis is differentiated from M. tornata by at least one translocation. The contribution of the structural changes in the chromosomes accounted for about 60% of the observed pollen sterility.

Early events in the embryo sac after intraspecific and interspecific pollinations in Rhododendron kawakamii and R. retusum

1986 ◽  
Vol 64 (2) ◽  
pp. 282-291 ◽  
Author(s):  
V. Kaul ◽  
J. L. Rouse ◽  
E. G. Williams
Keyword(s):  
Seed Set ◽  
Embryo Sac ◽  
Pollen Tubes ◽  
Interspecific Crosses ◽  
Primary Endosperm Nucleus ◽  
Kalmia Latifolia ◽  
Taxonomic Grouping ◽  
Similarities And Differences ◽  
Normal Fertilization

Early events in the embryo sac of Rhododendron kawakamii and R. retusum have been studied after compatible self-pollinations and eight interspecific crosses, using sectioned ovaries, pistil squashes, and seed-set data. Ovules of Rhododendron kawakamii and R. retusum are anatropous, unitegmic, and tenuinucellate, with a typical eight-nucleate, seven-celled embryo sac. Fertilization normally occurs 4–5 days after pollination. The zygote lays down a callose wall but remains undivided during the first 13–15 days after pollination. The primary endosperm nucleus divides soon after fertilization, and development is cellular ab initio. Crosses of R. kawakamii (♂) with R. santapaui and R. retusum and crosses of R. retusum (♂) with R. kawakamii, R. santapaui, R. ovatum, and R. tashiroi showed apparently normal fertilization in a majority of ovules entered by pollen tubes. In crosses of R. kawakamii (♂) with R. quadrasianum and Kalmia latifolia entry of pollen tubes into ovules was delayed and frequently abnormal. Apart from compatible self-pollinations of R. kawakamii an R. retusum, only the cross of R. kawakamii (♂) with R. santapaui produced healthy seedlings. Of the remaining seven interspecific crosses only three showed significant embryo development in control pistils left to mature in situ. Similarities and differences in the breeding behaviour of R. kawakamii and R. retusum are discussed with reference to their taxonomic grouping within subsection Pseudovireya.

Intergeneric hybrids of Hordeum vulgare with Agropyron caninum and A. dasystachyum

1985 ◽  
Vol 27 (4) ◽  
pp. 387-392 ◽  
Author(s):  
George Fedak
Keyword(s):  
Hordeum Vulgare ◽  
Chromosome Pairing ◽  
Meiotic Chromosome ◽  
Intergeneric Hybrids ◽  
Spindle Fibre ◽  
Chromosome Behavior ◽  
Paternal Parent ◽  
Agropyron Caninum

Hybrids were obtained by pollinating Hordeum vulgare cv. Betzes with Agropyron caninum (4x) and A. dasystachyum (4x) at frequencies of 1.4 and 6.1% of pollinated florets, respectively. The hybrids were sterile and phenotypically resembled the paternal parent, except for floret structure which was intermediate between the parental types. Chromosome pairing at meiosis was very low and thus provided no indication of homoeology between parental genomes. Abnormal meiotic chromosome behavior in meiocytes that occurred in sectors on the 'Betzes' × A. dasystachyum hybrid was attributed to abnormal spindle fibre function.Key words: intergeneric hybrids, Hordeum vulgare, Agropyron caninum, Agropyron dasystachyum.

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.

Meiotic behaviour of induced autotetraploids in Triticum L.

Genome ◽  
1990 ◽  
Vol 33 (2) ◽  
pp. 302-307 ◽  
Author(s):  
Yang Yen ◽  
Gordon Kimber
Keyword(s):  
Chromosome Pairing ◽  
Seed Set ◽  
Chromosome Association ◽  
Meiotic Behaviour ◽  
Meiotic Analysis

Colchicine-induced autotetraploids of Triticum speltoides, T. longissimum, T. sharonense, T. bicorne, T. uniaristatum, T. monococcum, and T. tauschii were all morphologically similar to but larger than their diploid forms. Seed set was lower than in the diploids except for the autotetraploid T. speltoides. Meiotic analysis showed fewer quadrivalents and more bivalents than would be expected in all of these autotetraploids. Arm-pair switch, indicated by complex trivalents and quadrivalents, was found and involved 0.1% of total chromosomes in T. umbellulatum, 0.5% in T. longissimum, 0.7% in both T. sharonense and T. tauschii, 6.3% in T. bicorne, and 15.3% in T. uniaristatum.Key words: meiosis, chromosome association, arm-pair switch, chromosome pairing, bivalentization.

Overlooked morphological variation and a proposal for a new taxonomic circumscription of Alyssum simplex (Brassicaceae)

Phytotaxa ◽  
2019 ◽  
Vol 416 (2) ◽  
pp. 149-166
Author(s):  
VERONIKA CETLOVÁ ◽  
JAVIER FUERTES-AGUILAR ◽  
DARIA IUDOVA ◽  
STANISLAV ŠPANIEL
Keyword(s):  
Genome Size ◽  
Genetic Markers ◽  
Geographic Distribution ◽  
Morphological Variation ◽  
Related Species ◽  
Evolutionary History ◽  
Separate Species ◽  
Taxonomic Treatment ◽  
Morphological Differences

A recent study of European annual taxa of Alyssum has revealed that A. simplex includes two cytotypes (diploid and tetraploid) which differ in genetic markers, evolutionary history, and monoploid relative genome size. In this paper we present a new taxonomic treatment of A. simplex in which we treat the two cytotypes as two separate species. We select and discuss suitable names for both taxa (diploid A. simplex and tetraploid A. collinum), examine their morphological differences and survey their geographic distribution. In addition, we compare both cytotypes with the morphologically similar and genetically related species A. strigosum and designate lectotypes and a neotype of several relevant names.

Systematic relationships of the Guianan brush-tailed rat (Isothrix sinnamariensis ) and its first occurrence in Guyana / Systématique du rat à queue en brosse de Guyane ( Isothrix sinnamariensis ) et première découverte en Guyane

Mammalia ◽  
2006 ◽  
Vol 70 (1-2) ◽  
Author(s):  
Burton K. Lim ◽  
Mark D. Engstrom ◽  
John C. Patton ◽  
John W. Bickham
Keyword(s):  
Dna Sequences ◽  
French Guiana ◽  
Tropical Rainforest ◽  
Sequence Difference ◽  
Separate Species ◽  
Adult Females ◽  
First Occurrence ◽  
Systematic Relationships ◽  
Average Sequence ◽  
Morphological Differences

AbstractIsothrix sinnamariensis was originally described and known only from French Guiana. We document the first occurence of this species from Guyana. A single sub-adult male was collected in lowland tropical rainforest near the headwaters of the Essequibo River. Although smaller in external and cranial size than the two adult females of the type description, our third known specimen represents the basal lineage to the type-series clade, with an average sequence difference of 1.72% based on cytochrome b mitochondrial DNA sequences. However, the degree of morphological and genetic divergence (2.67%) between I. sinnamariensis and its sister taxon I. pagurus is substantially less than the chromosomal differences originally used to distinguish them as two separate species. In contrast, distinctive karyotypes, morphological differences, and higher levels of mtDNA divergence (13.48%) between the other two species recognized, I. negrensis that was recently separated from I. bistriata , suggest an earlier and deeper diversification for these taxa.

Izmir subterranean clover (Trifolium subterraneum L. var. subterraneum)

2007 ◽  
Vol 47 (2) ◽  
pp. 226 ◽  
Author(s):  
P. G. H. Nichols ◽  
G. A. Sandral ◽  
B. S. Dear ◽  
C. T. de Koning ◽  
D. L. Lloyd ◽  
...  
Keyword(s):  
Seed Production ◽  
Seed Set ◽  
New South ◽  
South Australia ◽  
Subterranean Clover ◽  
Trifolium Subterraneum ◽  
Good Seed ◽  
Improvement Program ◽  
South Wales ◽  
Pasture Legume

Izmir is a hardseeded, early flowering, subterranean clover of var. subterraneum (Katz. et Morley) Zohary and Heller collected from Turkey and developed by the collaborating organisations of the National Annual Pasture Legume Improvement Program. It is a more hardseeded replacement for Nungarin and best suited to well-drained, moderately acidic soils in areas with a growing season of less than 4.5 months. Izmir seed production and regeneration densities in 3-year pasture phases were similar to Nungarin in 21 trials across southern Australia, but markedly greater in years following a crop or no seed set. Over all measurements, Izmir produced 10% more winter herbage and 7% more spring herbage than Nungarin. Its greater hardseededness and good seed production, makes it better suited to cropping rotations than Nungarin. Softening of Izmir hard seeds occurs later in the summer–autumn period than Nungarin, giving it slightly greater protection from seed losses following false breaks to the season. Izmir is recommended for sowing in Western Australia, New South Wales, Victoria, South Australia and Queensland. Izmir has been granted Plant Breeders Rights in Australia.

Synaptic mutants in hexaploid oats (Avena sativa L.)

Genome ◽  
1988 ◽  
Vol 30 (1) ◽  
pp. 1-7 ◽  
Author(s):  
H. W. Rines ◽  
S. S. Johnson
Keyword(s):  
Chromosome Pairing ◽  
Sodium Azide ◽  
Avena Sativa ◽  
Seed Set ◽  
Single Gene ◽  
Inheritance Pattern ◽  
Late Prophase ◽  
Homologous Chromosomes ◽  
Breeding Station ◽  
Meiotic Synapsis

Three meiotic synapsis-deficient mutants of oats (Avena sativa L.) were analyzed to determine their inheritance pattern, detailed chromosomal behavior, and location to chromosome. These highly sterile mutants, one in the cultivar 'Stout' and two in 'Noble', had been recovered from progeny of sodium azide mutagenized populations. Each segregated as a single gene recessive. The only synapsis-deficient variants previously described in hexaploid oats have been nullisomics or ditelosomics. Mutant 'Stout 1212' was classified as asynaptic due to deficiencies in chromosome pairing at all meiotic stages. Mutants 'Noble 1362' and 'Noble 1911' were classified as desynaptic since their homologous chromosomes were paired in early meiosis but they disassociated prematurely in late prophase I. Using a partial monosomic series from the Welsh Plant Breeding Station, mutant 1212 was mapped to monosome XII and is probably a mutation in Syn-5, a gene previously defined only by its nulli effect. Mutants 1362 and 1911 were mapped to monosome IV and are probably mutations in Syn-1, a gene also previously defined only by its nulli effect. Seed set on the synaptic mutant plants in the field was less than 0.2% of that on fertile sibs and likely resulted from pollination by surrounding fertile plants. This seed may serve as a source of unique aneuploid stocks in oats.Key words: meiotic mutants, gene mapping, monosomics, nullisomics, oat cytogenetics.

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