Browsing by Author "Carneiro, M. F."
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- Cryopreservation of pollen of carob treePublication . Custódio, Luísa; Romano, Anabela; Fernandes, N.; Carneiro, M. F.In this work, anthers isolated from male flowers of carob tree (Ceratonia siliqua L.) at developmental phase II were cryopreserved by vitrification, using a fast freezing method. Different types of carbohydrates at different concentrations, namely sorbitol (0.5 M, 1 M, and 2 M), mannitol (0.5 M and 1 M), sucrose (0.5 M, 1 M, and 2 M), and glucose (0.5 M, I M, and 2 M), namely sorbitol, mannitol, sucrose and glucose, were compared with respect to their capacity of inducing freeze tolerance in pollen of carob tree. Carbohydrates were applied as a pre-treatment to anthers before cryostorage. It was also assessed if the presence of the cryoprotectant during the storage period was beneficial for pollen viability. The viability of cryopreserved pollen was evaluated after 5 and 8 months of storage. The application of the cryoprotectants generally increased pollen viability as compared with the control. The best results were obtained after 5 months storage, in the presence of the cryoprotector, with pollen pre-treated with sucrose 0.5 M. The viability of pollen decreased with increasing the duration of storage period.
- Microsporogenesis and anther culture in carob tree (Ceratonia siliqua L.)Publication . Custódio, Luísa; Carneiro, M. F.; Romano, AnabelaAn in vivo study was made on male flowers of carob tree (Ceratonia siliqua L.), in order to establish a correlation between the flower and anther development, and microsporogenesis. In addition studies were conducted to find which phase is more appropriate for anther culture and haploid production. During the development of male flowers, six stages were identified. The male gametophytic cycle begins when flowers are in developmental phase 0, with the formation of the epidermis, endothecium, primary sporogencous tissue, primary parietal cells and pollen mother cells. During developmental phase I we observed the formation of pollen mother cells, the microspore tetrads, and uni- and binucleate pollen grains. At developmental phase II, uni- and binucleate microspores, and completely formed pollen grains were observed. In developmental phase III we could observe mature pollen grains ready to be released from the anthers as single binucleate pollen grains. Anthers from flowers at developmental phases I and II, with microspores at late uninucleate to early binucleate stage, were cultured in semi-solid Murashige and Skoog's (MS) medium supplemented with 2,4-dichlorophenoxyacetic acid (2,4-D) combined with one of the citokinins: N-6-benzyladenine (BA), kinetin (Kin), zeatin (Zea) and thidiazuron (TDZ). To obtain embryogenic calli anthers should be collected from flowers in developmental phase I. High frequencies of callogenesis were obtained, and the best medium for calli induction was MS supplemented with 0.5 mg l(-1) 2,4-D + 4 mg l(-1) TDZ. The frequency of haploid cells was found to be 17.2%. (C) 2004 Elsevier B.V. All rights reserved.