Genome doubling and chromosome elimination with fragment recombination leading to the formation of Brassica rapa–type plants with genomic alterations in crosses with Orychophragmus violaceus

Genome ◽  
2007 ◽  
Vol 50 (11) ◽  
pp. 985-993 ◽  
Author(s):  
Min Liu ◽  
Zai-Yun Li
Keyword(s):  
Brassica Rapa ◽  
Embryo Rescue ◽  
Chromosome Elimination ◽  
Intergeneric Hybrids ◽  
Aflp Analysis ◽  
Genetic Introgression ◽  
Orychophragmus Violaceus ◽  
Distant Hybridization ◽  
Genome Doubling ◽  
Mother Cells

In distant hybridization of plants, nonclassical hybrids with unexpected chromosome complements, chromosome elimination, and genetic introgression have been well documented. We obtained intergeneric hybrids between Brassica rapa , B. rapa var. chinensis, and another cruciferous species, Orychophragmus violaceus , following embryo rescue. Hybrids mainly displayed phenotypes of B. rapa, although certain O. violaceus or novel characteristics also appeared. Variable numbers of chromosomes were observed in somatic cells in the roots of plantlets on medium and in ovaries and pollen mother cells (PMCs). However, higher numbers were recorded in the roots. GISH revealed that the majority of ovary cells and PMCs contained 20 chromosomes of B. rapa with or without individual O. violaceus chromosomes or fragments added or introgressed. AFLP analysis showed that fragments deleted from the B. rapa genome were much more frequent than novel and O. violaceus fragments. The mechanisms involved genome doubling and successive elimination of O. violaceus chromosomes accompanied by fragment recombination and introgression, producing B. rapa–type plants with modified genetic constitutions and phenotypes.

Cytogenetic and molecular characterization of intergeneric hybrids between Brassica napus and Orychophragmus violaceus

Genome ◽  
2002 ◽  
Vol 45 (1) ◽  
pp. 110-115 ◽  
Author(s):  
B F Cheng ◽  
G Séguin-Swartz ◽  
D J Somers
Keyword(s):  
Brassica Napus ◽  
Morphological Traits ◽  
Embryo Rescue ◽  
Chromosome Elimination ◽  
Intergeneric Hybrids ◽  
Intergeneric Hybridization ◽  
Orychophragmus Violaceus ◽  
Group Iii ◽  
Group I ◽  
Group Ii

Twenty-two intergeneric hybrids from a cross between Brassica napus (AACC, 2n = 38) cultivar Oro and the ornamental crucifer Orychophragmus violaceus (OO, 2n = 24) were produced without embryo rescue. The plants were classified into three groups based on morphological and cytological observations and RAPD banding patterns. Plants of Group I had morphological traits of both parents and 2n = 29 chromosomes. In these plants, 62.1% of the pollen mother cells (PMCs) had the pairing configuration 1 III + 9 II + 8 I; the remaining PMCs had 10 II + 9 I. The plants possessed 97.6–98.8% B. napus specific and 9.2–11.7% O. violaceus specific RAPD fragments. Plants of Group II exhibited novel morphological traits and possessed 2n = 35, 36, or 37 chromosomes. Plants of Group III were morphologically similar to B. napus and possessed 2n = 19, 37, 38, or 39 chromosomes. Plants of Group II and Group III had 94.1–99.4% B. napus specific RAPD fragments and no O. violaceus specific RAPD fragments. Chromosome fragments were observed in PMCs of most of the F1 plants in all groups. Based on the cytological results and RAPD analysis, it is suggested that genome doubling and chromosome elimination occurred in the intergeneric hybrids of B. napus × O. violaceus.Key words: Brassica, intergeneric hybridization, meiosis, RAPD, chromosome elimination.

Coenocytism, ameiosis, and chromosome diminution in intergeneric hybrids in the perennial Triticeae

Genome ◽  
1988 ◽  
Vol 30 (5) ◽  
pp. 766-775 ◽  
Author(s):  
Richard R.-C. Wang
Keyword(s):  
Intergeneric Hybrid ◽  
Chromosome Elimination ◽  
Intergeneric Hybrids ◽  
Pollen Grain ◽  
Unreduced Gamete ◽  
Pollen Mother Cells ◽  
Psathyrostachys Juncea ◽  
Hybrid Plants ◽  
Mother Cells ◽  
Pollen Grain Wall

Three different pathways of ameiotic microsporogenesis were observed in some intergeneric hybrids of the perennial Triticeae grasses. In one of the hybrids between Pseudoroegneria spicata ssp. inermis and Psathyrostachys juncea, pollen mother cells remained as premeiotic interphase cells when the pollen grain wall started to form. The microspores in such an ameiotic plant are presumably unreduced. Coenocyte formation coupled with ameiosis occurred in two hybrid plants of Psathyrostachys huashanica × Secale montanum. Less than 10% of the pollen mother cells had one nucleus. An average of 4.44 nuclei, ranging from 1 to 25 per pollen mother cell, was observed. The nuclei in coenocytes remained unfused when the pollen grain wall was formed. Nucleus splitting followed by cytoplasmic budding or cleavage, possibly a process of chromosome diminution or elimination, replaced meiotic divisions in most of the pollen mother cells in one plant of Leymus angustus × Hordeum bulbosum and two plants of Thinopyrum elongatum × Psathyrostachys juncea. It is evident that these meiotic abnormalities are under genetic control. Probable locations for these genes controlling these phenomena are suggested.Key words: coenocyte, ameiosis, chromosome diminution, chromosome elimination, microsporogenesis, unreduced gamete, polyploidy, intergeneric hybrid.

Progenies of Thinopyrum elongatum × Agropyron mongolicum

Genome ◽  
1987 ◽  
Vol 29 (5) ◽  
pp. 738-743 ◽  
Author(s):  
Richard R-C. Wang
Keyword(s):  
Embryo Rescue ◽  
Chromosome Elimination ◽  
Root Tip ◽  
Hybrid Necrosis ◽  
Genome Chromosome ◽  
Pollen Mother Cells ◽  
Close Phylogenetic Relationship ◽  
Mother Cells ◽  
Thinopyrum Elongatum ◽  
High Degree

With the aid of embryo rescue, both a monoploid and several hybrids were obtained from the cross Thinopyrum elongatum × Agropyron mongolicum. The monoploid was a result of gradual and eventually complete elimination of A. mongolicum chromosomes in the hybrid. About 95% of the root-tip cells, and nearly all of the pollen mother cells, had only the seven chromosomes of the Je genome of the maternal parent. Very little autosyndesis occurred between chromosomes within the Je genome. Extensive chromosome pairings were observed in one headed hybrid, averaging 6.42 I + 2.53 rod II + 0.85 ring II + 0.25 III + 0.02 IV at metaphase I in pollen mother cells, which revealed a high degree of chromosome homology between the two genomes and thus justifying the close phylogenetic relationship between the two species. All plants died from hybrid necrosis, some as seedlings and some after heading. The Je and P genomes in the accessions used in this study carry complementary genes for hybrid necrosis. Key words: hybrid (intergeneric), haploid, genome, chromosome elimination, meiosis.

Diploid perennial intergeneric hybrids in the tribe Triticeae. IV. Hybrids among Thinopyrum bessarabicum, Pseudoroegneria spicata, and Secale montanum

Genome ◽  
1988 ◽  
Vol 30 (3) ◽  
pp. 356-360 ◽  
Author(s):  
Richard R.-C. Wang
Keyword(s):  
Meiotic Chromosome ◽  
Embryo Rescue ◽  
Intergeneric Hybrids ◽  
Root Tip ◽  
Pseudoroegneria Spicata ◽  
Genome Phylogeny ◽  
Karyotype Analyses ◽  
Thinopyrum Bessarabicum ◽  
Mother Cells ◽  
Secale Montanum

Diploid intergeneric hybrids among Thinopyrum bessarabicum, Pseudoroegneria spicata, and Secale montanum were synthesized with the aid of embryo rescue. Karyotype analyses of mitotic root-tip cells revealed that all satellited chromosomes in the J, S, and R genomes were present in their hybrid combinations, making it possible to identify these hybrids at the seedling stage. Spikes of these hybrids were intermediate to, but distinctly different from, those of the parental species. Meiotic chromosome associations at metaphase I in the pollen mother cells averaged 4.34 I + 2.77 rod II + 1.42 ring II + 0.24 III + 0.14 IV for P. spicata × T. bessarabicum; 11.05 I + 1.22 rod II + 0.04 ring II + 0.13 III + 0.01 IV for T. bessarabicum × S. montanum; and 12.98 I + 0.52 rod II + 0.01 III for P. spicata × S. montanum. These meiotic data suggest that the S genome of Pseudoroegneria and the J genome of Thinopyrum are more closely related to each other than they are with the R genome of Secale. The R genome is slightly closer to the J genome than to the S genome. Since these synthetic hybrids represent genomic combinations that may not exist in nature, their induced amphiploids should be created and evaluated.Key words: intergeneric hybrids, genome, phylogeny, Thinopyrum, Pseudoroegneria, Secale.

Alteration of chromosome behavior and synchronization of parental chromosomes after successive generations in Brassica napus × Orychophragmus violaceus hybrids

Genome ◽  
2007 ◽  
Vol 50 (2) ◽  
pp. 226-233 ◽  
Author(s):  
Zhigang Zhao ◽  
Ni Ma ◽  
Zaiyun Li
Keyword(s):  
Brassica Napus ◽  
Meiotic Division ◽  
Morphological Characteristics ◽  
Intergeneric Hybrids ◽  
Orychophragmus Violaceus ◽  
Genome Separation ◽  
Cytogenetic Evidence ◽  
Successive Generations ◽  
Mother Cells

In an earlier study, the progenies of intergeneric hybrids Brassica napus (2n = 38) × Orychophragmus violaceus (2n = 24) were investigated in successive generations (F1–F4) for the cytological phenomenon of parental genome separation during mitotic and meiotic division. In the present study, inbred lines (F5–F8) derived from 1 such hybrid were characterized for morphology, chromosome pairing behaviour, and genome composition. One F5 plant (2n = 31) with slightly yellow petals and 12:19 and 15:16 segregation ratios in its pollen mother cells (PMCs) produced F6 plants with distinct morphological characteristics and wide variations in fertility and chromosome numbers (2n = 25–38). F7 and F8 lines with distinctive morphology and wide ranges in chromsome numbers were established. In PMCs of F7 plants from 4 F6 plants, 0–12 labelled chromosomes from O. violaceus, which predominantly appeared as bivalents, were identified by genomic in situ hybridization. They behaved synchronously with B. napus chromosomes during meiotic division. The results provide molecular cytogenetic evidence of the inclusion of O. violaceus chromosomes in the original hybrids and the cytology in the hybrids documented earlier. They also show that chromosome behaviour was altered and the parental chromosomes became synchronized after successive generations.

scholarly journals VARIATION AMONG PERENNIAL RYEGRASS x TALL FESCUE PLANTS FROM TISSUE CULTURE

1988 ◽  
pp. 81-86
Author(s):  
A.G. Scott ◽  
D.W.R. White
Keyword(s):  
Tissue Culture ◽  
Lolium Perenne ◽  
Perennial Ryegrass ◽  
Tall Fescue ◽  
Festuca Arundinacea ◽  
Chromosome Doubling ◽  
Chromosome Elimination ◽  
Intergeneric Hybrids ◽  
Hybrid Plants ◽  
Spontaneous Chromosome

Tissue culture was used in an attempt to obtain a fertile perennial ryegrass x tall fescue hybrid. Regenerated hybrid plants were found to be morphologically variable and contain extensive chromosome rearrangements. Spontaneous chromosome doubling had occurred as well as chromosome elimination. though no fertile hybrid plants have been obtained to date. Keywords: somaclonal variation, Lolium perenne, Festuca arundinacea, intergeneric hybrids

Inter-family distant hybridization of Oryza sativa and Oenothera biennis

2008 ◽  
Vol 5 (3) ◽  
pp. 197-203
Author(s):  
Chu Xiu-Cheng ◽  
Zhao Ji-Hong ◽  
Chai Yang ◽  
Zhao Jian-Feng ◽  
Zhao Yun-Yang ◽  
...  
Keyword(s):  
Oryza Sativa ◽  
Variable Coefficients ◽  
Aflp Analysis ◽  
Parental Line ◽  
Oenothera Biennis ◽  
Distant Hybridization ◽  
Distinct Variable ◽  
Panicle Number ◽  
Pedigree Selection ◽  
Developmental Traits

AbstractProgenies derived from rice (Oryza sativa ssp. japonica) plants pollinated by Oenothera biennis exhibited numerous morphological and developmental traits. Some variant individuals appeared in generation D2. From generations D3 to D6, a large number of variants were observed, showing distinct variable traits including giant embryos. Statistical analysis on D6 lines showed significant differences between progenies and their rice parental line in several main traits, including plant height (49.2–164.5 cm), panicle number (12.1–38.2), panicle length (20.3–30.3 cm), length of sword leaf (13.8–57.5 cm), leaf width (11.1–25.2 mm), grain number of main panicle (142.0–367.0), percentage of seed setting (0.8–99.0%), 1000-grain weight (19.7–33.8 g) and time from germination to panicle emergence (90.0–108.0 days). Most of the variable coefficients were above 20% (the highest was 40.8%). Through pedigree selection of these plants, genetically stable lines were obtained, which are useful for rice breeding. Results from amplified fragment length polymorphism (AFLP) analysis showed that several rice lines contained extensive genetic variations, which included disappearance of rice parental bands and/or appearance of novel bands.

Sign in / Sign up

Export Citation Format

Share Document