Extensive Chromosome Breakage Occurring Spontaneously in a Certain Individual of Elymus Farctus. (=agropyron Junceum)

Heneen, Waheeb K.

doi:10.1111/j.1601-5223.1963.tb01865.x

Cited by 20 publications

(2 citation statements)

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“…The level of cytogenetic disorders can be extremely high, as was observed in a single Elymus farctus (Viv.) Runemark ex Melderis plant (Heneen 1963 ). There is a common agreement that heterochromatin is involved in these changes, and in the species mentioned above, large blocks of terminal heterochromatin have been discovered (Endo and Gill 1984 ).…”

Section: Introductionmentioning

confidence: 99%

Cytogenetic events in the endosperm of amphiploid Avena magna × A. longiglumis

Tomaszewska

Kosina

2021

J Plant Res

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This study analysed cytogenetic events occurring in the syncytial endosperm of the Avena magna H. C. Murphy & Terrell × Avena longiglumis Durieu amphiploid, which is a product of two wild species having different genomes. Selection through the elimination of chromosomes and their fragments, including those translocated, decreased the level of ploidy in the endosperm below the expected 3n, leading to the modal number close to 2n. During intergenomic translocations, fragments of the heterochromatin-rich C-genome were transferred to the D and Al genomes. Terminal and non-reciprocal exchanges dominated, whereas other types of translocations, including microexchanges, were less common. Using two probes and by counterstaining with DAPI, the A. longiglumis and the rare exchanges between the D and Al genomes were detected by GISH. The large discontinuity in the probe labelling in the C chromosomes demonstrated inequality in the distribution of repetitive sequences along the chromosome and probable intragenomic rearrangements. In the nucleus, the spatial arrangement of genomes was non-random and showed a sectorial-concentric pattern, which can vary during the cell cycle, especially in the less stable tissue like the hybrid endosperm.

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Section: Introductionmentioning

confidence: 99%

Cytogenetic events in the endosperm of amphiploid Avena magna × A. longiglumis

Tomaszewska

Kosina

2021

J Plant Res

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“…All three Elymus species are perennials, E. striatulus vegetatively propagating by rhizomes, whereas E. rechingeri and E. diae are tufted grasses. These aspects are evidently of relevance in the maintenance and survival of plants with chromosome structural rearrangements which otherwise might be deleterious (HENEEN 1963).…”

Section: Vegetative Propagation and Chromosomal Polymorphismmentioning

confidence: 99%

Chromosomal polymorphism in isolated populations of Elymus (Agropyron) in the Aegean:

Heneen

2009

Hereditas

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A striking chromosomal polymorphism predominates in Elymus striatulus (2n = 14), E. rechingeri (2n = 28) and E. diue (2n = 56) which grow in small isolated populations largely on the Aegean islands. The polymorphism was expressed mainly in the existence of several variant types of the satellite chromosomes. Satellite chromosomes might be more susceptible to structural alterations due to the presence of secondary constrictions, nucleolar organizers, heterochromatic blocks and repetitive DNA which are known to be labile sites. Chromosomal polymorphism was more pronounced in the two polyploid species which might be attributed to the compensatory effect of the high number of homologous, homoeologous or related genomes in the polyploids. Chromosomal polymorphism was also favored by the rhizomatous or tufted patterns of vegetative growth of these species. The evolutionary aspects of the chromosomal, genetical and morphological differences between populations might be related to ( I ) inbreeding of crossfertilizers and selection for chromosomal heterogeneity and/or (2) drift or a founder effect which is also supported by the paleogeographical records. The species in the Aegean area are apparently in an active phase of evolutionary change. W . K . Heneen, Institute of Genetics, University of Lund, S-223 62 Lund. SwedenElymus striatulus (2n = 14), E. rechingeri (2n = 28) and E. dine (2n=56) are three littoral species found by RUNEMARK in the Aegean. They grow in small isolated populations. Seeds collected from natural populations mainly on the Aegean islands were grown under greenhouse conditions. Cytological analysis of the plants raised from these seeds provided evidence for the prevalence of chromosomal polymorphism in the three species (HENEEN and RUNEMARK 1962, 1972 HENEEN 1977a, b, c). This polymorphism was manifested in the variable appearance of the satellite chromosomes and the presence of structurally new chromosome types (markers).In Table 1 a summary is presented of the data on the numbers of plants studied and the populations they represented, and also the number of satellite and marker chromosome constitutions present. The appearance of the different types of the satellite and marker chromosomes is shown schematically in Fig. 1. Satellite chromosome types A and B were found in all three species which indicates a similarity or close similarity between these species with respect to at least one genome. Variants of satellite types A and B as well as variants of type C (found only in E. rechingeri) were present either in a homo-or heterozygous condition.Satellite chromosome constitutions that were most common and thus most probably characteristic for the species were A2A2 BIBl for E. striatulus, A2A2 BIB1 C2C2 for E. rechingeri and possibly AA AA BB for E. diue. The original papers (cited above) should be consulted for details on numerical, structural and pairing peculiarities of the chromosomes in the three species and in the offspring from inter-and intrapopulation crosses in the case of E. rechingeri.The pre...

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