Ontogeny of Different Tetrad Types in the Single Microsporangium of Mitrephora tomentosa (Annonaceae)

Annonaceae, comprising approximately 107 genera and 2400 species, is the largest family among early-divergent Magnoliales. Previous studies have concentrated on binding mechanism that holds together four members of tetrads in Annonaceae. However, development mechanisms different tetrad types remain largely unknown. Mitrephora tomentosa was found to exhibit five permanent types, with two or three them existing same microsporangium, which ideal for studying formation pollens a single microsporangium explaining relationship between cytokinesis pollen types. The ontogenetic M. investigated using electron microscopy technologies, histochemical staining, immunocytochemistry. During meiosis, mother cells produce decussate tetragonal by successive tetrahedral rhomboidal simultaneous cytokinesis. Bidirectional callose deposition observed tetrahedral, tetragonal, rhomboidal, tetrads. variations process microsporogenesis randomly accumulate manifest as combinations deposition, leading differently shaped In mature pollens, microspores are connected both simple cohesion cytoplasmic channels, also play an important role maintaining synchronization members.