Occurrence and significance of polysomaty in species of Mimosa L.

Abstract

Polysomaty is the occurrence of cells with different ploidy levels in the same organ or tissue and there are records of this in root-tip cells of some Mimosa species. The objective of the present work was to verify the occurrence, possible cause and significance of polysomaty in a range of species of this genus. In root-tip cells of 68 accessions of 43 diploid and tetraploid Mimosa species, the percentage of polysomatic cells ranged from 5% to 87%. Pretreatment with the antimitotic paradichlorobenzene did not cause polysomaty but increased it in some accessions. When relating seedling root size and percentage of polysomatic cells, for most of the species a higher percentage of polysomatic cells was found in roots from 6 to 10 cm length. For M. scabrella (“bracatinga”), a comparative analysis of seedling root-tip cells and root-tip cells from well-developed plants kept in pots in a greenhouse showed that polysomaty occurred only in the seedling root-tips. The data suggest that, in Mimosa, polysomaty occurs...