Genome size and numerical polymorphism for the B chromosome in races of maize (Zea mays ssp. mays,Poaceae)

MARCELA ROSATO, AMILCAR M. CHIAVARINO, CARLOS A. NARANJO,JULIAN CAMARA HERNANDEZ Y LIDIA POGGIO

AMERICAN JOURNAL OF BOTANY

BOTANICAL SOC AMER INC

Año: 1998 vol. 85 p. 168 - 174

0002-9122

Twenty-one native populations (1120 individuals) of maize from Northern Argentina were studied. These populations. which belong to 13 native races, were cultivated at different altitudes (80-3620 m). Nineteen of the populations analyzed showed B chromosome (Bs) numerical polymorphism. The frequency of individuals with Bs varied from 0 to 94%. The number of Bs per plant varied from 0 to 8 Bs. with the predominant doses being 0. 1. 2. and 3. Those populations with varying number of Bs showed a positive and statistically significant correlation of mean number of Bs with altitude. The DNA content, in plants without Bs (A-DNA)(2n = 20), of 17 populations of the 21 studied was determined. A 36% variation (5.0-6.8 pg) in A-DNA content was found. A significant negative correlation between A-DNA content and altitude of cultivation and between A-DNA content and mean number of Bs was found. This indicates that there is a close interrela¬tionship between the DNA content of A chromosomes and doses of Bs. These results suggest that there is a maximum limit to the mass of nuclear DNA so that Bs arc tolerated as long as this maximum limil is not exceeded. Key words: B chromosome; DNA content; genome size: maize; maize native races; Poaceae; Zea mays ssp. mays.