Th is study presents a morphoanatomical analysis of Dyckia ibicuiensis, D. polyclada and D. racinae stamens. Flowers at anthesis were desiccated and their stamens were processed using common microtechniques for light microscopic analysis. Morphologically, the androecium in these species is diff erentiated by the disposition of the stamens around the gynoecium and by general anther characteristics. Included stamens, with antesepalous fi laments diff erent from those of the antepetalous, anthers in a radial disposition, always curved, and sporangia facing the gynoecium characterize D. ibicuiensis and D. racinae. Th is confi guration results from the fi lament connation, as well as special anatomical characteristics of the anthers, such as the connective with thickenings. In addition, these species are diff erentiated by the U-shaped thickening in the endothecium. D. polyclada is characterized by its small, free and exserted stamens, with a very short common tube, its anthers, that are not curved or organized around the gynoecium, and its divergent sporangia. Th e anatomical and morphological characteristics identifi ed here are important for characterization of these species. Considering that the androecium is important in the delimitation of Dyckia, the increased use of these data should be equally important for other species and infrageneric groupings.
This paper presents a comparative description of the starch distribution in the anthers, microspores and pollen grains of Aechmea recurvata, Dyckia racinae and Tillandsia aeranthos. Flowers at different stages of development were processed according to plant microtechniques for observation by light microscope. Ten stages of embryological development were used as references for the comparative analysis of starch distribution and dynamics. The structural data showed a greater starch accumulation in the parietal layers and connective of D. racinae. It was observed that in the species studied, starch began to accumulate in microspore mother cell stage. The pollen grains in D. racinae and in T. aeranthos present two amylo genesis-amylolysis cycles, while A. recurvata presents only one. One amylogenesis-amylolysis cycle occurs in the parietal layers and/or connective tissue in all three species. The pollen grains in the three species are dispersed without starch and are characterized as the starchless type. Starch dynamics presents a close relation to the development of sporangia, microspores and pollen grains. It is believed that differences in the starch distribution and accumulation are related to the abiotic factors where the species are found. IntroductionThe effectiveness of the reproductive process in angiosperms depends on the viability of microspores, megaspores, pollen grains and embryo sac, where the dynamics and use of primary metabolites are essential in this process (Bhandari 1984;Delph et al. 1997;Shivanna 2003;Pacini et al. 2006;Konyar et al. 2013). The accumulation and mobilization of sugars, lipids and proteins are common during sporangia development and were demonstrated by microscopy, histochemistry, and biochemical, physiological and molecular assays (Pacini & Viegi 1995;Oliver et al. 2005;Lora et al. 2012;Konyar et al. 2013). Regarding to the sugars, their importance was demonstrated for maturation of the epidermis, endothecium and tapetum (Clément & Audran 1995;Clément et al. 1998;Castro & Clément 2007). In this subject, was also demonstrated that the middle layers also act in the access of sugars to the loculus (Clément & Audran 1995).Besides to supply the metabolic demand, sugars will compose the fibrous thickenings of the endothecium, the primexine and intine, and in some cases, also the exine (Walter & Doyle 1975;Horner & Pearson 1978). When preparing for the developmental events of pollen grains, including the pollination period, sugars can be accumulated as starch, callose, pectins, insoluble polysaccharides, disaccharides or monosaccharides (Pacini 1996;Aouali et al. 2001;Clément & Pacini 2001;Pacini et al. 2006). The starch acts on the metabolism or has a structural function (Pacini 1996). In metabolism, starch can be emphasized as an intermediate stage in the formation of oils in starchlesstype pollen grains (Miki-Hirosige & Nakamura 1983;Baker & Baker 1979). It may be possible for it to convert into sucrose for breathing and osmotic regulation (MikiHirosige & Nakamura 1983), o...
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
customersupport@researchsolutions.com
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply.
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.