Therefore, zygospores are the result of sexual reproduction. In the case of dormant spores in eukaryotes, sporogenesis often occurs as a result of fertilization or karyogamy forming a diploid spore equivalent to a zygote. The red alga Polysiphonia alternates between mitotic and meiotic sporogenesis and both processes are required to complete its complex reproductive life cycle. Other fungi, such as ascomycetes, utilize both mitotic and meiotic spores. Examples are the conidial fungi Aspergillus and Penicillium, for which mitospore formation appears to be the primary mode of reproduction. Mitotic sporogenesis is a form of asexual reproduction. In some cases, sporogenesis occurs via mitosis (e.g. Sporic meiosis is needed to complete the sexual life cycle of the organisms using it. Reproductive spores are generally the result of cell division, most commonly meiosis (e.g. 3.2 Zygospore, oospore and auxospore formation.3.1 Chlamydospore and teliospore formation.However, the processes of ontogeny and sporogenesis are extremely similar throughout the taxa studied, suggesting that they represent conservative family traits, nonspecific or generic.Ĭutin lignin lipids Lycopodiaceae sporogenesis sporopollenin starch. The transfusion cells and the perispore are not always present. Intrinsic fluorescence corroborates the presence of lignin and cutin in the sporangium wall, while the sporopollenin is restricted to the exospore. In contrast, starch is not detected in the spores, but is abundant in premeiotic sporocytes and immature tetrads, developmental stages of high cellular metabolic activity. The lipids were abundant in the sporocytes, tetrads and spores, representing the main source of energy of the latter. Mucopolysaccharides were found on the sporocyte coat and its abundance in sporangial cavity persists up to the immature tetrads stage, and then disappears. The perispore, if present, deposits at last. The endospore deposits as a thin inner layer composed of cellulose, pectin and carboxylated polysaccharides. As for the sporoderm development, the exospore is the first layer formed, composed by sporopollenin.
Cutinisation occurs in early stages of development of sporangium cell walls, but in their final stages walls become lignified.
Our results indicated that the ontogeny of sporangia and sporogenesis were very similar to the previously observed in Huperzia brevifolia. Strobili and sporangia were dehydrated with 2.2 dimethoxypropane, critical point dried and coated with gold for scanning electron microscopy (SEM). Sections were observed with photonic microscope equipped with differential interference contrast (DIC) and fluorescence microscopy (for spore and sporangium walls unstained). Chemical tests were also conducted in sections of fresh sporangia at different stages of maturity using alcian blue (mucopolysaccharides), Lugol solution (starch), Sudan III (lipids), phloroglucinol (lignin) and orcein (chromosomes). For other studies, paraplast plus-embedded sections (3-5μm) were stained with safranin-fast green and alcian blue-hematoxylin. Ontogeny was studied in small, 1cm long pieces of strobili and axis, which were fixed in glutaraldehyde or FAA, dehydrated in alcohol, embedded in LR White, sectioned in 0.2-0.5μm and stained with toluidine blue (TBO), a metachromatic dye that allows to detect both sporopollenin and lignin or its precursors, during these processes. Specimens were collected in three departments from the Colombian Andes between 1 454-3 677m altitude. The analyses were performed in 14 taxa of six genera of the family, Diphasiastrum, Diphasium, Huperzia (a genus which is treated here including Phlegmariurus), Lycopodiella, Lycopodium and Palhinhaea. Here we present a detailed study of the ontogeny of sporangia and sporogenesis, and the chemical determination of several compounds generated during spore formation. Studies on reproductive aspects of Lycopodiaceae are not very abundant in the scientific literature, and constitute essential information to support taxonomic and systematic relationships among the group. Ontogeny of the sporangium, spore formation and cytochemistry in Colombian Lycopodials (Lycopodiaceae). RINCON BARON, Edgar Javier HILDA ROLLERI, Cristina ALZATE GUARIN, Fernando and DORADO GALVEZ, Jacinta Mireya.