Genome Size, B Chromosomes and Karyotypic Parameters Variation of Andean Argentinian Maize Populations (Zea mays ssp. mays).

FOURASTIÉ, MF; POGGIO L; CÁMARA HERNÁNDEZ J; GONZÁLEZ GE

Foz do Iguaçu

Congreso; 21st International Chromosome Conference (ICC); 2016

In the present study, the variation in genome size, number and frequency of B chromosomes (Bs) and karyotype parameters was analyzed in 10 populations belonging to 4 maize landraces (Orgullo Cuarentón, Pisingallo, Amarillo Grande, and Garrapata) from the Andean region of the northwest of Argentina. These maize populations were collected in an altitudinal gradient from 910 to 3,900 m.a.s.l. The goal of the present study is to analyze the relationship between these cytogenetic parameters with the altitude of cultivation. Moreover, by studying different karyotype parameters, each population is characterized cytogenetically. The 2C value varied significantly among the populations studied, between 4.5 and 6.2 pg. The average number of Bs, from 0 to 2.7, and the frequencies of Bs, from 0 to 100%, also varied significantly among populations. Variations in different karyotype parameters, such as total chromosome length, intra- and interchromosomal asymmetry indexes, and the percentage of knob heterochromatin were detected. In particular, the heterochromatic knobs showed variations in number, size, and position in the karyotype. Furthermore, FISH experiments were performed to reveal the sequence composition of each knob. The results allowed us to construct a representative idiogram for each population studied, revealing the value of karyotype parameters in the cytogenetic characterization of native maize populations. The correlations found show that Bs and the percentage of heterochromatin are sources of the genome size variation. Besides, the correlations found among the altitude of cultivation with Bs, percentage of heterochromatin, and DNA content suggest that the prevailing environmental features of each altitude of cultivation may also modulate the nucleotype of each maize population from northwestern Argentina.Financial support: Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET-PIP 00342), Universidad de Buenos Aires (UBACYT), and the Agencia Nacional de Promoción Científica y Tecnológica-SECyT (PICT 01665)