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| Author(s): |
Aline Siqueira Nunes
Total Authors: 1
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| Document type: | Master's Dissertation |
| Press: | São Paulo. |
| Institution: | Universidade de São Paulo (USP). Instituto de Biociências (IBIOC/SB) |
| Defense date: | 2013-08-22 |
| Examining board members: |
Gladys Flávia de Albuquerque Melo de Pinna;
Mariane Silveira de Sousa Baena;
Diego Demarco
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| Advisor: | Gladys Flávia de Albuquerque Melo de Pinna |
| Abstract | |
Popularly known as flowering stones or ice plants, the species of Aizoaceae (Caryophyllales) are characterized by morphologically diverse succulent leaves. With center of origin in Southern Africa, most species are classified in the subfamily Ruschioidaeae, which present dorsiventral, cylindrical and three-angled leaved plants, being remarkable the occurrence of conation between the bases of opposite leaves, and the presence of peripheral vascular bundles with endoscopyc xylem. Our study shows that the formation of peripheral vascular bundles occurs after the marginal blastozone establishment, and abaxial tissues differentiate in the adaxial domain of the leaf, during blade histogenesis. We suggest that an abaxialization mechanism is involved in the formation of leaf margins in Aizoaceae. The xylem of peripheral vascular bundles is composed by wide band tracheids - wbts, a specialized type of cell that occurs only in Aizoaceae, Cactaceae Anacampserotaceae. The origin and function of this cell type has been the subject of study by some researchers. By means of comparative analysis of anatomy, ultrastructure and pectin immunolabeling, we conclude that the definition of \"wbts\" should be kept in the three families; however, we highlight the possibility of idioblasts tracheids in the some cases. This work contributes to the knowledge of leaf anatomy and ontogenesis in Aizoaceae, opening opportunities for studies on the mechanisms involved in the establishment of dorsiventrality in leaves with radial symmetry. A comparative analysis of wbts in Aizoaceae, Cactaceae Anacampserotaceae brings contributions to knowledge about their distribution and characteristics in different organs (AU) | |
| FAPESP's process: | 11/04286-0 - LEAF ONTOGENESIS IN RUSCHIOIDEAE (AIZOACEAE)BASED ON MORPHOLOGICAL PATTERNS AND PHYLOGENY |
| Grantee: | Aline Siqueira Nunes |
| Support Opportunities: | Scholarships in Brazil - Master |