CYTOGENETIC STUDIES IN AMARANTHUS.: III. Chromosome numbers and phylogenetic aspects

Grant, W. F.

doi:10.1139/g59-031

Cited by 66 publications

(40 citation statements)

References 13 publications

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“…Several authors have reported the chromosome number for the wild species studied in the present paper: A. bouchonii 2n = 32 (11-iigin 1987), A. hybridus 2n = 32 (Grant 1959, Queiros 1989 The results obtained in a previous work (Greizerstein and Poggio 1994) and in the present contribution point out that adequate techniques allow the description of the chromosome morphology, total DNA content and reveal karyotype differences among species in spite of their small chromosome size.…”

Section: Discussionsupporting

confidence: 61%

Karyological Studies in Five Wild Species of Amaranths.

1997

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A cytogenetic program in Amaranthus have been devised in our laboratory since 1988, in order to improve the karyological characterization of the species and cultivars, increase the knowledge of genetic resources and explore evolutionary trends (Greizerstein and Poggio 1992, 1994, 1995.Two chromosome numbers have been reported in the genus (2n = 32, 2n = 34) and in some cases both numbers occur in the same species, in addition to that of A. dubius L, the only species with 2n = 64. Pal et al. (1982) suggested that the gametic number n =17 originated from the n =16 through primary trisomy. Greizerstein andPoggio (1992, 1994), on the basis of the cytogenetic analysis of interspecific hybrids support this hypothesis, and propose that the species with 2n = 32 are polyploids (basic number x = 8) and that x1=16 is a derived basic number. The basic number x2= 17 would have appeared later by primary trisomy.In the present contribution we report the karyotype formulae and total DNA content of five wild species namely A. bouchonii Thellung., A. hybridus L., A. quitensis L., A. powelli Wats and A. spinosus L. with the aim of increasing the cytogenetic knowledge of this important genus. Materials and methodsThe material was provided by Ing. Agr. Guillermo Covas and was cultivated at the Instituto Fitotecnico Santa Catalina (IFSC), Llavallol, Pcia. de Buenos Aires, Argentina. Amaranthus bouchonii . . . . .Karyotype analysis: The observations have been done on root tip cells of germinating seeds. Pretreatment with colchicine 0.05% during 2-3 hr at room temperature in darkness, fixation in absolute ethanol-acetic acid (3 : 1) and stain with acetic-haematoxylin 2%. The nomenclature used for the description of the chromosome morphology is that proposed by Levan et al. (1964). To estimate the karyotype asymmetry, two numerical parameters were used according to Romero Zarco (1986): Al= (intrachromosomal asymmetry index) and A2= (interchromosomal index). Both indexes are independent of chromosome number and size.Determination of DNA content: DNA content was measured in telophase nuclei (2C) of the root apex of germinated seeds, following the procedure described by Tito et al. (1991). The optimal hydrolysis time was 45 min. The amount of Feulgen staining per nucleus, expressed in arbitrary units, was measured at a wavelength of 570 nm, using the scanning method with a Zeiss Universal microphotometer (UMSP 30). The DNA content per basic genome (2C value), expressed in picograms was calculated calibrating a cultivar of Amaranthus cruentus cv Don Guiem with Allium cepa var ailsa craig (2C = 33.55 pg, Bennett and Smith 1976) and the DNA content was calculated using A. cruentus cv Don Guiem (2C = 1.26 pg) as a standard. For each species, two accessions and 2-4 individuals in each one were measured. The

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Section: Discussionsupporting

confidence: 61%

Karyological Studies in Five Wild Species of Amaranths.

1997

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“…Palmer amaranth and spiny amaranth have been assigned as sister taxa in AFLP-based phylogenetic analyses (Wassom and Tranel 2005). These species have the same chromosome number of 2n ¼ 34 (Gaines et al 2012;Grant 1959a), similar genome sizes , and they share distinguishing leaf and pollen morphological characteristics (Franssen et al 2001). A high degree of internal transcribed spacer (ITS) sequence homology between Palmer amaranth and spiny amaranth has been reported (Kirkpatrick 1995).…”

Section: Taxonomy Reproductive Biology and Geneticsmentioning

confidence: 99%

“…The basic chromosome number in the Amaranthaceae is x ¼ 8 or x ¼ 9 (Turner 1994). Grant (1959a) reported that Palmer amaranth chromosomes are small (2 to 3 lm) and not well differentiated. Consistent with this, Rayburn et al (2005) Sauer 1950;Trucco et al 2005).…”

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confidence: 99%

Mechanism of extreme genetic recombination in weedy Amaranthus hybrids

Steinau

Skinner²,

Steinau

2003

Weed Science

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Interspecific hybridization of Palmer amaranth and common waterhemp produce hybrids with unique DNA fragments not found in either parent. The objective of this research was to investigate the mechanisms involved in the formation of the polymorphic fragments. Six novel fragments were cloned and sequenced. Five of the six were significantly similar to plant transposons, the sixth was similar to squamosa promoter–binding proteins from other plant species. Southern blot analysis using one of the novel fragments as probe revealed a consistent pattern of repetitive DNA that was species and biotype specific. These results indicate that transposon-like elements may play an important role in the formation of new fragments in Amaranthus hybrids derived from interspecific hybridization, suggesting that considerable instability of the hybrid genome may occur.

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confidence: 99%

“…Consistent with this, Rayburn et al (2005) reported the genome size of Palmer amaranth to be smaller than most of the weedy amaranths with 2C ¼ approximately 0.95 pg. Grant (1959a) gave a chromosome count for the species of 2n ¼ 34. Gaines et al (2012) also gave a chromosome count of 2n ¼ 34 for Palmer amaranth, although Rayburn et al (2005) reported 2n ¼ 32.…”

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confidence: 99%

Nonhybrid Progeny from Crosses of Dioecious Amaranths: Implications for Gene-Flow Research

Trucco¹,

Zheng

Woodyard

et al. 2007

Weed sci.

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Large proportions of nonhybrid progeny result from controlled crosses between Palmer amaranth and common waterhemp, both dioecious weeds. Agamospermy was proposed as an explanation for this phenomenon, and here we provide evidence in support of this hypothesis. We evaluated 60 nonhybrid offspring from two interspecific crosses, and all plants were females and had DNA content values similar to the female (Palmer amaranth) parent. Among nine hybrids resulting from these crosses, eight were nonviable (lethal or neuter), and only one hybrid allowed for continued gene movement. Cytogenetic evaluation of this hybrid revealed triploidy, further supporting the occurrence of unreduced gametes in these species. In light of this new evidence, we examine earlier data regarding Palmer amaranth by common waterhemp hybridization and suggest some prior conclusions may be premature.

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CYTOGENETIC STUDIES IN AMARANTHUS.: III. Chromosome numbers and phylogenetic aspects

Cited by 66 publications

References 13 publications

Karyological Studies in Five Wild Species of Amaranths.

Karyological Studies in Five Wild Species of Amaranths.

Mechanism of extreme genetic recombination in weedy Amaranthus hybrids

Nonhybrid Progeny from Crosses of Dioecious Amaranths: Implications for Gene-Flow Research

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