Are cytological parameters of maize landraces (Zea mays ssp. mays) adapted along an altitudinal cline?
J Plant Res
; 131(2): 285-296, 2018 Mar.
Article
em En
| MEDLINE
| ID: mdl-29177755
The Northwestern Argentina (NWA) highland region is one of the southernmost areas of native maize cultivation. We studied variations of different cytological parameters, such as DNA contents, presence/absence of B chromosomes (Bs), and number and sequence composition of heterochromatic knobs in ten accessions of four maize landraces growing along a broad altitudinal cline in NWA. The aim of this work was to assess variations in cytological parameters and their relationship with the crop altitude of cultivation, in an adaptive context. The A-DNA content of the A chromosome complements showed 40% of difference between the lowest (4.5 pg) and the highest (6.3 pg) 2C value. This variation could be attributed to differences in number and size of heterochromatic knobs. Fluorescent in situ hybridization studies revealed the sequence composition of each knob, with a higher proportion of knobs composed of 180-bp repeats rather than TR-1 repeats, in all accessions. We also found numerical polymorphisms and the highest frequency of Bs reported in maize to this date. These results lead us to propose that the frequencies and doses of Bs are influenced by the landrace genotypical make-up. The Bs might be maintained in higher frequencies in those accessions having lower heterochromatin content, so as to preserve an optimal nucleotype. Furthermore, selective forces acting along the altitudinal gradient might be modulating the cytological parameters studied, as suggested by the significant correlations found among them.
Palavras-chave
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Variação Genética
/
DNA de Plantas
/
Zea mays
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Cromossomos de Plantas
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Altitude
País/Região como assunto:
America do sul
/
Argentina
Idioma:
En
Revista:
J Plant Res
Assunto da revista:
BOTANICA
Ano de publicação:
2018
Tipo de documento:
Article
País de afiliação:
Argentina
País de publicação:
Japão