Chromosome Biology

Appels, R.; Morris, Rosalind; Gill, Bikram S.; May, Cedric E.

doi:10.1007/978-1-4615-5409-7

Cited by 38 publications

(36 citation statements)

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“…Others have also observed a relatively high production of hybrids but rare production of BC 1 progeny in many interspecific crosses involving weedy as well as cultivated Amaranthus species (Gupta and Gudu 1991;Pal and Khoshoo 1973;Wetzel et al 1999). Low fertility of interspecific hybrids is a common phenomenon and generally attributed to meiotic abnormalities related to a lack of complete pairing between chromosomes of the two parent species (Appels et al 1998).…”

Section: Resultsmentioning

confidence: 99%

Transmission of herbicide resistance from a monoecious to a dioecious weedy Amaranthus species

et al. 2002

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The genus Amaranthus includes several important monoecious and dioecious weed species, and several populations of these species have developed resistance to herbicides. These species are closely related and two or more species often coexist in agricultural settings. Collectively, these attributes raise the concern that herbicide resistance might transfer from one weedy Amaranthus species to another. We performed research to determine if a dominant allele encoding a herbicide-insensitive form of acetolactate synthase (ALS) could be transferred from a monoecious species, A. hybridus, to a dioecious species, A. rudis. Numerous F(1) hybrids were obtained from controlled crosses in a greenhouse between A. rudis and herbicide-resistant A. hybridus, and most (85%) of these hybrids were herbicide-resistant. Molecular analysis of the ALS gene was used to verify that herbicide-resistant hybrids contained both an A. rudis and an A. hybridus ALS allele. Although hybrids had greatly reduced fertility, 42 BC(1) plants were obtained by backcrossing 33 hybrids with male A. rudis. Fertility was greatly restored in BC(1) progeny, and numerous BC(2) progeny were obtained from a second backcross to A. rudis. The herbicide-resistance allele from A. hybridus was transmitted to 50% of the BC(1) progeny. The resistance allele was subsequently transmitted to and conferred herbicide resistance in 39 of 110 plants analyzed from four BC(2) families. Parental species, hybrids, and BC(2) progeny were compared for 2C nuclear DNA contents. The mean hybrid 2C nuclear DNA content, 1.27 pg, was equal to the average between A. rudis and A. hybridus, which had 2C DNA contents of 1.42 and 1.12 pg, respectively. The mean 2C DNA content of BC(2) plants, 1.40 pg, was significantly (alpha < 0.01) less than that of the recurring A. rudis parent and indicated that BC(2) plants were not polyploid. This report demonstrates that herbicide resistance can be acquired by A. rudis through a hybridization event with A. hybridus.

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Section: Resultsmentioning

confidence: 99%

Transmission of herbicide resistance from a monoecious to a dioecious weedy Amaranthus species

et al. 2002

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“…The synaptonemal complex formation is initiated at multiple sites, but within them there are primary and secondary centres of synapsis. The primary synapsis begins at the telomeric regions, congregated in one area of the nucleus (Appels et al, 1998). In the specimens from both species of Jadera analyzed, univalency involved almost always the same chromosome pair, but the origin of univalents can not be ascertained because of the characteristics of early prophase stages.…”

Section: Discussionmentioning

confidence: 96%

Autosomal univalents as a common meiotic feature in Jadera haematoloma (Herrich-Schaeffer, 1847) and Jadera sanguinolenta (Fabricius, 1775) (Heteroptera: Rhopalidae: Serinethinae)

Bressa¹,

Papeschi²,

Mola³

et al. 2001

Eur. J. Entomol.

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Abstract. So far, available cytogenetic data on 24 species of Rhopalidae reveal a male diploid chromosome number of 13, with a pair of m chromosomes and an X0/XX (male/female) sex chromosome determining system. As a rule Heteroptera have holokinetic chromosomes and a pre-reductional type of meiosis: the autosomal bivalents and the m pseudobivalent segregate reductionally at first meiotic division, while the X chromosome segregates equationally. In the present study, the meiotic chromosome behaviour was analyzed in males from different Argentinean populations of Jadera haematoloma and J. sanguinolenta. Our results corroborate the diploid chromosome number and general patterns of male meiosis previously reported by other authors in samples from Brazil and Texas (USA). Among bivalents, one is remarkably larger and may present one or two terminal chiasmata. Comparison of mean chiasma frequency between Jadera haematoloma (5.63) and J. sanguinolenta (5.14) revealed that differences are significant. In most individuals of both species the largest pair appears as univalents in a variable number of cells and shows a regular meiotic segrega tion. Autosomal univalents orientate axially at metaphase I (with their long axis parallel to the spindle axis) and segregate equationally at anaphase I. At metaphase II they associate end-to-end forming a pseudobivalent that segregates reductionally at anaphase II. An hypothesis is suggested to explain the appearance of the largest pair, either as a ring/rod bivalent or as univalents within the same individual, although an asynaptic or desynaptic origin of the univalents cannot be ascertained. The highly regular meiotic behaviour of this autosomal pair could ensure a high fertility of the individuals, and could be considered a selectively neutral condition or, at least, not detrimental.

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“…The number and location of the chiasmata during meiosis varied largely among cells. Such variation may be determined not only genetically, but also by environmental factors, both internal and external to the individual (John and Lewis, 1965;Jones, 1987;Appels et al, 1998). The presence of univalents and bivalents with two chiasmata in the same individual and even in the same cell may be a consequence of changes in the mechanisms regulating chiasma frequency and distribution.…”

Section: Discussionmentioning

confidence: 99%

Cytogenetic studies of three Lycosidae species from Argentina (Arachnida, Araneae)

et al. 2008

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Cytogenetic studies of the family Lycosidae (Arachnida: Araneae) are scarce. Less than 4% of the described species have been analyzed and the male haploid chromosome numbers ranged from 8+X 1 X 2 to 13+X 1 X 2 . Species formerly classified as Lycosa were the most studied ones. Our aim in this work was to perform a comparative analysis of the meiosis in "Lycosa" erythrognatha Lucas, "Lycosa" pampeana Holmberg and Schizocosa malitiosa (Tullgren). We also compared male and female karyotypes and characterized the heterochromatin of "L." erythrognatha. The males of the three species had 2n = 22, n = 10+X 1 X 2 , all the chromosomes were telocentric and there was generally a single chiasma per bivalent. In "Lycosa" pampeana, which is described cytogenetically for the first time herein, the bivalents and sex chromosomes showed a clustered arrangement at prometaphase I. The comparison of the male/female karyotypes (2n = 22/24) of "Lycosa" erythrognatha revealed that the sex chromosomes were the largest of the complement and that the autosomes decreased gradually in size. The analysis of the amount, composition and distribution of heterochromatin with C-banding and staining with DAPI-and CMA 3 -showed that "Lycosa" erythrognatha had little GC-rich heterochromatin in the pericentromeric region of all chromosomes. In addition, the actual occurrence of the genus Lycosa in the Southern Hemisphere is discussed.

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Chromosome Biology

Cited by 38 publications

References 0 publications

Transmission of herbicide resistance from a monoecious to a dioecious weedy Amaranthus species

Transmission of herbicide resistance from a monoecious to a dioecious weedy Amaranthus species

Autosomal univalents as a common meiotic feature in Jadera haematoloma (Herrich-Schaeffer, 1847) and Jadera sanguinolenta (Fabricius, 1775) (Heteroptera: Rhopalidae: Serinethinae)

Cytogenetic studies of three Lycosidae species from Argentina (Arachnida, Araneae)

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