Abstract:

The accumulation and distribution of nutrients during anther development are critical for pollen maturation. To investigate the cellular structure of the anther in Iris lactea，and to examine the dynamic changes in polysaccharides and lipid droplets，this study utilized anthers at different developmental stages as experimental material. Slide preparation and semi-thin sectioning techniques were employed to analyze the developmental characteristics of the anther wall and microspores. Histological staining was used to evaluate the spatiotemporal dynamics of polysaccharides and lipid droplets. Results showed that cytokinesis during meiosis of microspore mother cells in I. lactea occurs through multiple pathways，producing tetrads of tetrahedral，bilateral symmetry，and irregular configurations. Small vacuoles were observed in the cytoplasm of microspore mother cells，tetrad microspores，and uninucleate microspores，notably in the uninucleate microspores，which exhibited irregular shapes. Mature pollen grains were bicellular，predominantly elliptical in shape，with a small proportion triangular. The outer wall of the pollen exhibited reticulate ornamentation and prominent elongated germination furrows，characteristic of a distal monocolpate type. The anther wall of I. lactea comprised 3-4 layers of middle layer cells. During late anther development，the middle layer and endothecium cell walls exhibited fibrous thickening，while tapetum cells underwent in situ disintegration and degeneration，indicating a secretory type. In mature anthers，both the tapetum and middle layer disintegrated，leaving only the epidermis and fibrous layer. Microspores in I. lactea contained abundant lipid droplets throughout development. Consequently，mature pollen grains contained both starch granules and lipid droplets，indicating a mixed-type pollen. Tapetum cells began accumulating lipid droplets during the mother cell stage and actively secreted and transported them into the locule to support microspore development，while nutrient accumulation showing spatiotemporal specificity.

Key words: Iris lactea, anther development, nutrient, tapetum, pollen grain