The Cytogenetics of Oenothera

Cleland, Ralph E.

doi:10.1016/s0065-2660(08)60287-4

Cited by 62 publications

(38 citation statements)

References 94 publications

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“…Gametophytic and sporophytic lethals near translocation breakpoints are shown to be widespread in some plants (Cleland, 1962;James, 1965). However, it is difficult to estimate a priori the likelihood of their arising in a given genome region.…”

Section: Discussionmentioning

confidence: 99%

“…They regularly appear in the progenies of heterozygotes for translocations (eg, Ramage, 1960), which are known to be widespread in plant populations (Lewis, 1951;James, 1965;Wedberg et al, 1968). Moreover, it is well known that in wild populations, plants heterozygous for a translocation may contain sporophytic lethals near the breakpoints (Cleland, 1962;James, 1965). If recombination between the lethal and the breakpoint is suppressed, the progeny of a self-pollinated trisomic will consist predominantly of trisomics with the parental karyotype, because disomics die, and tetrasomics have a poor chance to survive due to severe genic imbalance (Figure 1).…”

Section: Introductionmentioning

confidence: 99%

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Tertiary trisomics in the garden pea as a model of B chromosome evolution in plants

et al. 2003

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It is hypothesized that, in plants, genetically empty B chromosomes may originate from the extra chromosome (E) of tertiary trisomics if (i) the region of basic chromosomes homologous to the E (H-region) harbors a sporophytic lethal covered by the wild-type allele in E, and (ii) crossing-over between E and the H-region is suppressed. Under these conditions, most loss-of-function mutations occurring in the H-region are deleterious for haploid gametophytes, whereas those occurring in E are neutral or advantageous for hyperploid (n þ 1) gametophytes. As a result, natural selection at the gametophyte level can lead to the degeneration of E, leaving the H-region intact. Using Hammarlund translocation T(3-6)a, we synthesized two trisomic lines of the garden pea (Pisum sativum L.), where E was composed of the short arms of chromosomes 3 and 6 and the H-region carried recessive markers. In the trisomic line TRIS, we found few crossovers between E and the H-region. In the trisomic line TRUST, obtained after a change of basic chromosome constitution, recombination in this region was completely suppressed. After induction in the H-region of TRUST of a recessive sporophytic mutation rmv, two 15-chromosome lines of stable trisomics were established. One of them passed 11 generations, having produced more than 6000 individuals, all of them trisomic, and E remained present as a single element with no pairing partners. No tetrasomics were dete-cted in these lines. If such trisomics occurred in nature, their extra chromosomes are likely to become a B chromosome.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Tertiary trisomics in the garden pea as a model of B chromosome evolution in plants

et al. 2003

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“…In Isotoma, this cannot be the case; male non-transmission and female non-transmission have both arisen amongst populations of complex heterozygotes with zygotic lethal systems. By the same token, the balanced zygotic lethal system in Oenothera lamarkiana (Cleland, 1936) may be taken to be a remnant of the original complex hybrid genetic system in that genus, but it has been replaced, almost completely, by gametic systems in virtually all other Oenothera complex hybrid species. The male non-transmissibility described for 3-mile Rock 18, Yorkrakine 7, etc, and here referred to as (male) gametic lethality, involves a failure of otherwise normally appearing pollen grains to germinate.…”

Section: Discussionmentioning

confidence: 99%

Complex hybridity in Isotoma petraea. VI. Distorted segregation, gametic lethal systems and population divergence

Lavery

James

1987

Heredity

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Unequal recovery of complexes in crosses involving Isotoma petraea complex heterozygotes may be due to (a) the components of the zygotic lethal system in one complex being distributed over both complexes in a second complex hybrid, (b) to the dependence of a complex containing a dominant lethal factor on a suppressor of that lethal in the other complex for its survival, and (c) to gametic lethals. The redistribution of zygotic lethal system components between complexes in different complex heterozygotes leads to a limitation of the number of complex combinations possible in interpopulational hybrids and to the development of partial genetic isolation between populations. Unbalanced gametic lethals, operating in either the pollen or ovule, are not uncommon in Isotoma complex hybrids, and one plant stabilised by a balanced gametic lethal system is described. It is concluded that balanced gametic lethal systems in Isotoma could eventually replace the more primitive zygotic lethal systems, and that a similar evolutionary sequence probably accounts for the preponderance of gametic lethal systems in Oenothera complex hybrids.

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“…The only comparisons among subspecies formally designated as such are in Phlox. However, the morphological similarities and the genomic compatibilities of species of the Oenothera biennis complex (Cleland, 1975), and of Stephanomeria exigua and a derivative referred to as "Malheurensis" (Gottlieb, 1973) are so great that I will treat them as subspecies here. In Oenothera as in Phlox, ecophysiological and morphological divergence between population systems have not been accompanied by allozymic divergence beyond that present between populations.…”

Section: Geographical Variation Patterns-sta-mentioning

confidence: 99%

Genetic Variation in Annual Phlox: Self‐compatible Versus Self‐incompatible Species

Levin

1978

Evolution

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The Cytogenetics of Oenothera

Cited by 62 publications

References 94 publications

Tertiary trisomics in the garden pea as a model of B chromosome evolution in plants

Tertiary trisomics in the garden pea as a model of B chromosome evolution in plants

Complex hybridity in Isotoma petraea. VI. Distorted segregation, gametic lethal systems and population divergence

Genetic Variation in Annual Phlox: Self‐compatible Versus Self‐incompatible Species

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