Cytogenetics, genome size and anther anatomy in Bulbostylis (Cyperaceae)

Abstract

Cyperaceae display diverse and unusual cytogenetical characteristics, but are still sparsely documented and poorly understood in this respect. Six new chromosome counts are presented for Bulbostylis. Absolute DNA content was close to 1 pg in all species and was independent from chromosome number. Despite variations in chromosome number from 2n = 30 to 2n = 102, DNA content only varied from 0.932 pg to 1.198 pg. The studies presented in this work showed that species possess holokinetic chromosomes. The size of stomata and pollen grains did not vary. These results would confirm that the chromosome evolution of these species was via agmatoploidy and symploidy rather than by polyploidy. Abnormalities during meiotic spindle formation in microsporogenesis followed by simultaneous cytokinesis resulted in four microspores, of which only one was functional, resulting in a pseudomonad maturing into pollen grains with the usual vegetative and generative nuclei in addition to three degenerated microspore nuclei.