Karyotype, meiotic behavior and pollen features of Senna occidentalis

Abstract

Meiotic behavior, pollen morphology, interphasic nucleus pattern and karyotype description for Senna occidentalis (Caesalpinioideae — Fabaceae) are presented. The species had non-reticulate interphasic nucleus and homogeneous chromosome condensing with minute distal late-condensing portions in prometaphase. In mitotic metaphase, chromosome number was 2n = 28 (9 m + 5 sm), with secondary constriction in one chromosome pair. Detection of four nucleoli indicated existence of two chromosome pairs bearing Nucleolar Organizer Region (NOR). Meiotic behavior was regular, with high meiotic index (95%). Pollen grains, classified as polar/spheroidal, presented 90% viability.