Cytological characterization of the Guarani?s maize landraces of Northeastern Argentina: variations in the genome size and the cytological markers

CÁMARA HERNÁNDEZ, JULIÁN; REALINI, MARÍA FLORENCIA; GONZÁLEZ, GRACIELA; POGGIO, LIDIA

Foz de Iguazú

Congreso; 21st International Chromosome Conference; 2016

Sociedad Brasileira de Genética

To contribute to the knowledge of the cytogenetic diversity of the Guarani?s maize landraces, we studied 20 populations from Northeastern Argentina (NEA). In indigenous settings from the subtropical forests of the Misiones Province, up to 15 Guarani?s maize landraces maize were found. They showed remarkable phenotypic differences and high genetic diversity despite growing in a small and restricted eco-geographical area, without significant differences in altitude, climatic or biological conditions. We performed DAPI staining and FISH techniques using as probes: the knob (180-pb and TR-1), rDNA (18S and 5S) and centromeric (CentC and CMR) repetitive sequences. We also evaluated the variability of the genome size by flow cytometry. In Zea, knobs have been observed in 34 distinct cytological locations, varying in number, size, and sequences composition. Previous studies reported that the differences in the DNA content were related with the variations in the number and size of the knobs. However, the variation of other repetitive sequences could not be discarded. The Guarani?s populations presented knobs, with different frequencies, in almost all chromosome arms (except 6S). The number (8-22), percentage (ca.5% to 18%), and sequence compositions of the knobs showed variability among populations. Moreover, variation in the percentage of CentC and CMR sequences were detected. Karyotypic parameters and FISH allowed the characterization of each population. The 2C value presented inter-populational (4.62pg to 6.29pg) and intra-populational (1.63-fold and 1.08-fold) variation. This study is a contribution to the knowledge and conservation of the maize landraces, which is important due to increasing threats of the gene pool of native maize.