Occurrence of spontaneous triploidy in Manihot esculenta Crantz

Abstract

The spontaneous occurrence of a triploid is reported in Manihot esculenta Crantz collected in Sape-PB, Brazil. Mitotic analysis showed a stable chromosome number of 2n=54, with chromosome size and morphology very similar to the diploid species. The chromosome behavior in meiosis was irregular in the metaphase-anaphase I, with occurrence of uni, bi and trivalents. The average number of univalents per cell was 7.2. In the tetrad stage, a higher number of micronuclei were found, resulting in almost 100% of abnormal tetrads and pollen sterility. Triploid was also characterized by having larger and fewer stomata than diploid species.