INVESTIGADORES
ESPINOZA francisco
artículos
Título:
Evidence for autoploidy in apomictic Paspalum rufum.
Autor/es:
QUARIN, C. L.; FRANCISCO ESPINOZA; NORRMANN, G. A.
Revista:
HEREDITAS
Editorial:
WILEY-BLACKWELL PUBLISHING, INC
Referencias:
Año: 1998 vol. 129 p. 119 - 124
ISSN:
0018-0661
Resumen:
Puspalurn ru/um is a taxonomically well defined species which includes two cytotypes: sexual self-incompatible diploids (2n = 2x = 20), and apomictic, pseudogamous, and self-fertile tetrapioids (2n = 4x = 40). The two cytotypes are morphologically very similar. The hypothesis of autoploidy in 4x apomictic strains was cytologically tested using 3x and 4x interploid hybrids as well as an induced autotetraploid plant. Controlled 2x x 4x crosses produced one 3x hybrid (B,,, n + n) and two 4x hybrids (B,,,, 2n + n). The autotetraploid plant was induced from the diploid strain by colchicine treatment. At meiosis the triploid B,, hybrid showed a mean of 7.4 trivalents per pollen mother cell (PMC) and up to 9 trivalents were present in 28´%, of the PMCs. This indicates a strong homology between genomes of the 2x and the 4x parents. Moreover, the means of quadrivalent chromosome associations per PMC were similar in the natural tetraploid (2.6), the induced autotetraploid (3.l), and the B,,, tetraploid hybrids (3.6) suggesting that natural tetraploid strains originated by autoploidy. These results are in agreement with previous findings and support the hypothesis that autoploidy has played an important role in the origin and evolution of apomixis in warm-season grasses.