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Abstract
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.
Keywords: Airborne particulate material (APM); connective; microsporogenesis; protein bands; Tapetum
1. Introduction
The rapid increase in industrial and agricultural technology has been accompanied by a marked increase in the number and types of biologically active agents released into the biosphere. These agents can produce either mutagenic or physiological effects or a combination of both, and their effects can occur in any cell and at any stage of life cycle. Most of these agents act directly, but in some cases, they have unpredictable indirect effects [1].
Pollen grains house the male gamets (or their progenitor cells) and arise from microspore mother cells through programmed developmental stages, which are supported by the tapetum, the cell layer of the anther wall. Pollen grains are released into the air for fertilization. During this stage they can be attacked directly by air pollutants. Indirect effects of air pollution on anther and pollen are possible due to pollutants entering to the soil and this alters the pH [2, 3]. Root injury can result from the subsequent mobilization of trace element [2, 3]. Alternatively pollutants may interfere with aerial growth...