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| Author(s): |
Natalie do Valle Capelli
Total Authors: 1
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| Document type: | Doctoral Thesis |
| Press: | São Paulo. |
| Institution: | Universidade de São Paulo (USP). Instituto de Biociências (IBIOC/SB) |
| Defense date: | 2022-02-08 |
| Examining board members: |
Diego Demarco;
Ana Cristina Andrade de Aguiar Dias;
Gladys Flávia de Albuquerque Melo de Pinna;
André Olmos Simões
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| Advisor: | Diego Demarco; Marcelo José Pena Ferreira |
| Abstract | |
Floral nectaries in the Apocynaceae family can occupy different positions, or present different structures and strategies for the release and storage of nectar, being a good model for the study of the evolution of this gland concerning the diversification of the family. We analyzed the structure, position, and origin of Apocynaceae nectaries, focusing on their heterotopic evolution. For this study, we used flowers belonging to the groups Rauvolfioideae, Apocynoidaeae, Periplocoideae, and Asclepiadoideae. In the Rauvolfioideae and Apocynoideae grades, nectary is present in some species and absent in others. In both grades, the nectaries may have different morphologies, which may be inconspicuous, projections lateral to the ovary, or forming a continuous or lobed disc around the ovary or on top of the ovary. Anatomically, these nectaries are composed of epidermis and parenchyma, or just by nectary parenchyma. As for the release of nectar, it can occur through the epidermis when it is nectariferous, through stomata when only the parenchyma is nectariferous, or even, in some cases it can be released in a mixed way when the epidermis is secretory and the stomata are also present. The origin of these nectaries in most species belonging to Rauvolfioideae is from the ovary, and in a few species from the receptacle; in Apocynoideae the origin may be from the receptacle, corolla, or ovary. In the flowers of Asclepiadoideae, the primary nectaries originate from the androecium, in the interstaminal areas of the filament tube; additionally, some genera have nectaries originating from the corona, mainly in the staminal position (secondary nectaries), and may also present tertiary nectaries when there is an annular corona. The nectaries of the Asclepiadoideae are composed only of either just an epidermis or epidermis and a few more layers of subepidermal parenchyma cells. These nectaries do not have stomata and the nectar is released directly from the epidermis. The heterotopy of these floral nectaries may reflect new pollination strategies related to the greater diversification of these flowers within the family. (AU) | |
| FAPESP's process: | 18/09200-6 - Heterotopic evolution of the floral nectaries in Apocynaceae and their implications in the pollination |
| Grantee: | Natalie Do Valle Capelli |
| Support Opportunities: | Scholarships in Brazil - Doctorate |