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.

rRNA distribution during microspore development in anthers of Beta vulgaris L. quantitative in situ hybridization analysis

1996 ◽  
Vol 109 (4) ◽  
pp. 859-866
Author(s):  
A. Majewska-Sawka ◽  
M.I. Rodriguez-Garcia
Keyword(s):  
Beta Vulgaris ◽  
Transcriptional Activity ◽  
Morphological Characteristics ◽  
Rrna Synthesis ◽  
Ultrastructural Organization ◽  
Rrna Processing ◽  
Microspore Development ◽  
Mother Cells ◽  
In Situ Hybridizations

We related changes in the ultrastructural organization of the nucleoli with the results of quantitative in situ hybridizations to characterize rRNA metabolism during the development of microspore mother cells in the sugar beet anther (Beta vulgaris L.). In the course of meiotic prophase and early postmeiotic interphase the morphological characteristics of the nucleoli are typical of low or no transcriptional activity and a low rate of rRNA processing. However, we found evidence of an apparent increase in the relative numbers of 18 S rRNA transcripts in some stages of microsporogenesis. This was found in both the nucleoli and cytoplasm of pachytene meiocytes, and in later stages there was a spectacular accumulation of rRNA transcripts in nucleoli of the tetrad cells. Quantitative data are analyzed in the light of morphometric findings in the cell and their compartments to elucidate the degree to which changes in cell size are related to changes in labeling density and distribution. The results are discussed in terms of rRNA synthesis, transport and degradation as processes involved in the regulation of rRNA within microsporocytes and microspores.

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.

A fertile amphiploid between diploid wheat (Triticum tauschii) and crested wheatgrass (Agropyron cristatum)

Genome ◽  
1999 ◽  
Vol 42 (3) ◽  
pp. 519-524 ◽  
Author(s):  
A Martín ◽  
A Cabrera ◽  
E Esteban ◽  
P Hernández ◽  
M C Ramírez ◽  
...  
Keyword(s):  
Intergeneric Hybrids ◽  
Agropyron Cristatum ◽  
Evolutionary Mechanisms ◽  
Triticum Tauschii ◽  
New Crops ◽  
Breeding Programmes ◽  
Diploid Level ◽  
Mother Cells ◽  
Tetraploid Parent

Alloploidy, one of the most efficient evolutionary mechanisms in nature, has not been extensively exploited in plant breeding programmes. Many genomic combinations remain to be created by plant breeders, to be used directly as new crops or indirectly to widen the genetic basis of crops. The Triticeae tribe, to which wheat belongs, is among the botanical groups in which this strategy has been successfully explored. However, there remain valuable genomic combinations that have not been obtained at the diploid level. The Agropyron complex (wheat-grasses) has recently been the focus of attention for interspecific hybridization, but intergeneric hybrids or amphiploids with wheat have not been reported at the diploid level. Here we report synthesis of a tetraploid amphiploid between Triticum tauschii and Agropyron cristatum by crossing two tetraploid accessions. Using total genome in situ hybridization (GISH) staining on metaphase I pollen mother cells, data on allosyndetic and autosyndetic chromosome pairing have been obtained. These data support the view that the A. cristatum tetraploid parent used in the synthesis of the amphiploid has a segmental alloploidy nature.

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.

scholarly journals Identification of Parental Genome Construction and Inherited Morphological Characteristics in Triploid and AneuploidIntergeneric Hybrids from a Diploid−Diploid Cross between Citrus and Fortunella

Agronomy ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 1988
Author(s):  
Kiichi Yasuda ◽  
Masaki Yahata ◽  
Mai Sato ◽  
Miki Sudo ◽  
Akiyoshi Tominaga ◽  
...  
Keyword(s):  
Morphological Characteristics ◽  
Intergeneric Hybrids ◽  
Unreduced Gametes ◽  
Unreduced Gamete ◽  
Parental Genome ◽  
Chromomycin A3 ◽  
Horticultural Traits ◽  
Ssr Genotyping ◽  
Intermediate Traits

We previously obtained two intergeneric hybrids with different ploidies, i.e., aneuploid (2n = 28) and eutriploid, from diploid−diploid crosses between ‘Kiyomi’ tangor (Citrus unshiu Marcow. × C. sinensis (L.) Osbeck) and Meiwa kumquat (Fortunella crassifolia Swingle) as novel breeding materials for a seedless kumquat. In this study, we attempted to clarify the construction of the parental genomes of these hybrids by SSR genotyping and genomic in situ hybridization (GISH)−chromomycin A3 (CMA) analysis. SSR genotyping in NSX43 (LG5) and CiBE2227 (LG8) loci revealed that both hybrids inherited one allele from ‘Kiyomi’ tangor and two heterozygous alleles from Meiwa kumquat. The GISH analysis failed due to the high genomic homology between Citrus and Fortunella. At the same time, the CMA karyotype compositions of the two intergeneric hybrids (H15-701: 2A + 1B + 3C + 13D + 7E + 1F + 1Dst; H15-702: 3A + 1B + 2C + 15D + 4E +1F + 1Dst) and both parents (‘Kiyomi’ tangor: 1A + 2B + 2C + 6D + 7E; Meiwa kumquat: 2A + 2C + 12D + 1F + 1Dst) were completely revealed. We identified the parental genome construction and polyploidization processes in both intergeneric hybrids on the basis of these SSR genotypes and CMA karyotype compositions according to the following theory: the SSR genotypes and chromosome compositions were the same as those of the somatic chromosome and two-fold after the first division (even number) in unreduced gametes caused by first-division restitution (FDR) and second-division restitution (SDR), respectively. Consequently, we determined that both intergeneric hybrids may have had two genomes derived from the 2n male unreduced gamete as a result of the FDR of the Meiwa kumquat. In addition, most horticultural traits of the leaves, flowers, and fruits of both hybrids showed intermediate traits of the parents, but the fruit sizes and flowering habits were more like those of the two inherited genomes of Meiwa kumquat.

Sign in / Sign up

Export Citation Format

Share Document