Evaluation of meiotic abnormalities and pollen viability in aposporous and sexual tetraploid Paspalum notatum (Poaceae)

Abstract

We analyzed anaphase I configurations and pollen viability in aposporous and sexual tetraploid (2n = 4x = 40) cytotypes of Paspalum notatum. Five natural aposporous accessions and three experimentally obtained sexual individuals were used. In addition, 16 (8aposporous and 8 sexual) F1 hybrids, previously classified by their mode of reproduction, were analyzed. Cytogenetic observations revealed normal and abnormal anaphase I configurations in both aposporous and sexual genotypes. Anaphase I abnormalities were mainly laggard chromosomes, chromatin bridges, and micronuclei. On average, 44.36 % of aposporous meiocytes and 29.66 % of sexual ones showed abnormal anaphase I configurations. The total numbers of normal and abnormal anaphase I were highly significantly different between aposporous and sexual strains. The pollen viability test indicated that aposporous individuals had significantly more non-viable pollen than sexual ones; a positive correlation (r = 0.71; r2 = 0.50) between the variables was detected. Analysis of aposporous and sexual hybrids confirmed differences in the numbers of normal and abnormal anaphase I patterns in the aposporous and sexual parents. However, similar proportions of viable pollen were produced by both groups of hybrids. In this case, the variables were not correlated (r = 0.23; r2 = 0.05). Data from this study indicated that aposporous strains had a genetic rearrangement affecting meiosis that was absent in the experimentally obtained sexual individuals and that it was transmitted to the progeny. The possible association between meiotic abnormalities and the inheritance of apospory is discussed.