Document Type: Regular Paper
Department of Biology, Shahid Bahounar University, Kerman, Iran
The study aimed to investigate the microsporogenesis, tapetum and pollen development in Petunia hybrida Juss.
under control and air pollution condition. The connective shows a well-developed placentoid, giving the
sporogenous tissue a crescent-shape. The sporogenous tissue of each of the four anther locules is surrounded by
dimorphic tapetum. The outer (towards the epidermis) and inner (towards the connective) tapetal layers differ in
shape, staining intensity and degree of vacuolization. During microsporogenesis and pollen maturation, the
tapetum undergoes several changes and ultimately degenerates after pollen mitosis. The tapetum is the secretory
type. Microsporogenesis with simultaneous cytokinesis forms tetrahedral tetrads of microspores. Mature pollen
grains are prolate, tricolporate/tricolporoidate with furrows disposed along the polar axis and three lowly
developed pores with striate-reticulate sculpture. Under air pollution, microsporogenesis was normal till tetrad
stage. After this stage, some tetrahedral tetrads were still present and some pollen grains were irregular shaped,
shrunk and fragile. Some tapetal cells were smaller and the number of their nuclei was less compared to those of
the control. Cellular material release was higher in polluted pollen. SDS-PAGE pattern in polluted pollen did not
show significant difference compared to the control.