Microsporogenesis in Monocotyledons

Abstract

This paper critically reviews the distribution of microsporogenesis types in relation to recent concepts in monocot systematics. Two basic types of microsporogenesis are generally recognized : successive and simultaneous, although intermediates occur. These are characterized by differences in tetrad morphology, generally tetragonal or tetrahedral, although other forms occur, particularly associated with successive division. Successive microsporogenesis is predominant in monocotyledons, although the simultaneous type characterizes the ' lower ' Asparagales. Simultaneous microsporogenesis also occurs in Japonolirion and Petrosa ia (unplaced taxa), some Araceae, Aponogeton, Thalassia and Tofieldia (Alismatales), Dioscorea, Stenomeris and Tacca (Dioscoreales), and some Commelinanae : Arecaceae (Arecales), and Cyperaceae, Juncaceae and Thurniaceae (Poales). Simultaneous microsporogenesis is of phylogenetic significance within some of these groups, for example, Asparagales, Dioscoreales and Poales. An intermediate type is recorded in Stemonaceae (Pandanales), Commelinaceae (Commelinales) and in Eriocaulaceae and Flagellariaceae (Poales). There is little direct relationship between microsporogenesis type and pollen aperture type in monocots (except for trichotomosulcate and pantoporate apertures), although trichotomosulcate apertures in monocot pollen, and equatorial tricolpate and tricolporate apertures in eudicot pollen, are all related to simultaneous microsporogenesis.# 1999 Annals of Botany Company Huynh K-L. 1976. Arrangement of some monosulcate, disulcate, trisulcate, dicolpate, and tricolpate pollen types in the tetrads, and some aspects of evolution in the angiosperms. In : Ferguson IK, Muller J, eds. The e olutionary significance of the exine. London : Academic Press, 101-124. Huynh K-L. 1980. La morphologie du pollen de Pandanus subg. Vinsonia (Pandanaceae) et sa signification taxonomique. Pollen et Spores 22 : 173-189. Huynh K-L, Stone BE. 1981. On a new subsection of Pandanus section Cauliflora (Pandanaceae) with paniculate staminate inflorescence structure, distinctive leaf anatomy and pollen morphology.

Cytomixis and meiotic abnormalities during microsporogenesis are responsible for male sterility and chromosome variations in Houttuynia cordata

“…Simultaneous microsporogenesis is plesiomorphic in angiosperms, although the successive type occurs in some early branching lineages and is especially characteristic of some monocotyledons (Furness and Rudall, 1999). The eudicot clade of angiosperms is characterized by simultaneous microsporogenesis and tricolpate pollen apertures.…”

Microsporogenesis and anther development in Bromeliaceae

“…Within Poales, successive microsporogenesis is recorded for Mayacaceae (Venturelli & Bouman 1986), Typhaceae (Furness & Rudall 1999b) but not for Rapateaceae which possesses the simultaneous type (Venturelli & Bouman 1988).…”

Normal microspore production after cell fusion in Brachiaria jubata (Gramineae)

“…In the simultaneous type, the first meiotic division is followed directly by the second, and then cytokinesis and callose deposition occur, forming four microspores (Furness et al, 2002). Although cytokinesis is predominantly of the successive type among monocotyledons, Furness and Rudall (1999) demonstrated that microsporogenesis is a significant character at the ordinal level, and simultaneous microsporogenesis has evolved independently in several monocot groups. The arrangement of the four microspores is varied, resulting in differently shaped tetrads (Furness et al, 2002).…”