Karyotype comparation between Zea luxurians and maize Amarillo Chico through DAPI-banding and FISH of knob sequence

GONZÁLEZ, GE; FOURASTIÉ, MF; POGGIO, L

Maize Genetics Cooperation Newsletter

Maize Genetics Cooperation Newsletter

Lugar: Missouri; Año: 2010 vol. 84 p. 1 - 3

1090-4573

The variation in DNA content in Zea has been proposed that is largely caused by differences in the heterochromatin amounts that form distal blocks named knobs. These knobs may vary in quantity and size among the different races of maize and its wild relatives. Zea luxurians possesses the highest genome size of the 2n=20 Zea species (2C= 8.83 pg), while the DNA content of maize varies between 2C=4.92 and 6.79 pg. The heterochromatic knobs from maize and Zea luxurians correspond to C and DAPI-positive bands on mitotic metaphase chromosomes, and there are composed principally by a 180-bp tandem repeat sequence.The materials used in this study were the Zea luxurians cv. 9478 (Guatemalan) Leg. CIMMYT and the Argentinean race of maize Amarillo Chico (VAV 6451) from NOA Leg. by Vavilov Laboratory, University of Buenos Aires (UBA). We revealed, using DAPI-banding and FISH, that Zea luxurians have about 14%more knob-heterochromatin than maize, indeed knobs of Zea luxurians are about 40% bigger than the maize ones (Fig. 1). Moreover, we observed that the TCL of Zea luxurians is 28.6 % higher than maize, being approximately 26% if knobs are not considered. Also, we have seen that the Total Chromosome Volume of Zea luxurians is about 28% higher than maize. Therefore, the differences in DNA content and the chromosome sizes between both species could be explicated for both its dissimilar number and size of knobs, and the different amounts of interspersed DNA.We conclude that the difference founded in inter-chromosomal asymmetry in the taxa studied is due to the number, size and distribution of heterochromatic knobs on both chromosomes arms. Finally, the cytogenetic studies presented here revealed important karyotypic and chromosomal differences between Zea luxurians and maize.