Abstract
In this study, the development of male reproductive organ was analysed in Crataegus tanacetifolia (Lam.) Pers., endemic to Turkey. Androecium is composed of 20 stamens which are attached at the base of the filaments. The anther wall formation follows the dicotyledonous type. The undifferentiated anther is ovoid-shaped, and the differentiation starts with the appearance of archesporial cells. Mature anthers are dorsifix and tetrasporangiate. The anther wall is composed of an epidermis, endothecium, two or three rows of middle layers and secretory tapetum. Endothecial cells show fibrous thickening. Tapetum is characterized by enlarged secretory types with binucleate cells, which presented an intense reaction with regard to proteins, insoluble polysaccharides and lipids. Features of chromatin condensation and nucleus disorders identified with the application of DAPI (4´,6-diaminido-2-phenylindole) point out programmed cell death. Epidermal and endothecial layers remain intact until anther dehiscence; however, middle layer and tapetum disappear during development. At the end of regular meiotic division, tetrahedral microspore tetrads are formed. Pollen grains are tricolparatae, tectate and sphaeroidea. Exine is made up of lipoidal substances and proteins, but the intine includes insoluble polysaccharides. Further, cytoplasm of pollen grains are rich in proteins, lipids and insoluble polysaccharides.
Highlights
Crataegus tanacetifolia (Lam.) Pers. belongs to genusCrataegus of the subfamily Maloideae of Rosaceae (Campbell et al, 2007)
This paper provides knowledge on anther ontogeny, anther wall development, microspore development, pollen morphology and cytochemical features; by the application of light, fluorescence and scanning electron microscopy
Structure of the androecium Androecium of C. tanacetifolia consists of 20 stamens (Fig. 1a) which attached at the base of the filaments (Fig. 1c)
Summary
Crataegus tanacetifolia (Lam.) Pers. belongs to genusCrataegus of the subfamily Maloideae of Rosaceae (Campbell et al, 2007). According to Davis and Browicz (1972), there are 17 species, one subspecies and a few varieties of Crataegus, which grow naturally in Turkey. C. tanacetifolia is an important endemic species to Turkey and widely spreads in Bolu, Karabük, Kastamonu and Ankara. Morphological characters of the male gametophyte and details of microsporogenesis are useful in taxonomic studies for defining the circumscription of taxones. There are some taxonomically important characters such as; variability in the number of anther layers, thickening in endothecium, number of rows in middle layer, arrangement of tetrads within the callosic wall, number of pollen pores or colpes and bi or tricellular pollen grains (Galati et al, 2006; Gotelli et al, 2006; Liu and Huang, 2003). The number of tapetum and the type of tapetum have taxonomic value in the sense that all members of most angiosperm families have the same type (Davis, 1966; Johri et al, 1992)
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