https://repositorio.ufu.br/handle/123456789/18960 2026-09-19T10:47:22Z https://repositorio.ufu.br/handle/123456789/50195 Title: Tendências evolutivas no androceu de Melastomataceae: estudos morfológicos e anatômicos dos estames e anteras em gêneros de Melastomeae Abstract: Members of Melastomataceae family usually have actinomorphic and bisexual flowers. The most important pollinator of the plants of this family is female bees which are able to vibrate its poricidal anthers and remove pollen, although there are spontaneous self-pollination species and also apomitic species. In addition to this diversity of reproductive systems, variations throughout the development of the anther wall can take place, ensuing in diversification of parietal layer composition. However, most studies have focused on individuals of the Miconieae tribe; hence there is a necessity to look into these variations in other tribes, specially the most representative in Brazil among them, the Melastomeae. Thus, an objective of this study was to describe the morphology and anatomical structure of the stamens in different Melastomeae genera: Acisanthera P.Browne (2 sp.), Comolia DC. (2 sp.), Poteranthera Bong. (1 sp.), Siphanthera Pohl (2 sp.) and Tibouchina Aubl. (5 sp.), attempting to identify and understand, from an evolutionary point of view, the changes found apart from pointing out some features that can assist in the delimitation of these genera and tribes (Chapter 1). This research also aimed to study the floral biology and reproductive system of the smallest species of Melastomataceae known so far, Poteranthera pusilla Bong (Chapter 2). The morphological and anatomical studies, including the vascularization of stamens, were performed according to the usual techniques of plant anatomy; and P. pusilla reproductive biology was studied under control pollination, pollen viability and pollen tube growth. The morphological results have shown that most of the studied species has dimorphic androecium containing ten stamens, which has antesepal stamens larger than antepetals, as well as other members of Melastomeae. But some species have eight stamens of which the four antepetals may be reduced to staminodes, such as S. gracillima. Another modification that has been found is the total loss of one of the cycles of stamens which happens in P. pusilla. During the study about the development of the anther wall, the monocotyledon type was identified on A. genliseoides, A. quadrata, S. foliosa, S. gracillima and T. villosissima and variations of the monocotyledon type have been ascertained on C. lanceiflora, C. sertularia, P. pusilla, T. candolleana, T. herbacea, T. heteromalla and T. stenocarpa. During the whole of microsporogenesis, of all species, the parietal layer of the anther consists of epidermis, endothecium, middle layer and tapetum, differing only in the number of middle layers. At the stage of anthesis just the epidermis is relentless, except for Comolia specieis that also exhibit part of the endothecium. In the course of the vascularization analysis, the trace bundles are larger on antesepals stamens and may be absent on the reduced antepetals, as in A. genliseoides and S. foliosa. These morphological and anatomical studies of the stamens and anthers support the available information up to now about an evolutionary trend towards decreasing the size and number of stamens in Melastomataceae. This decrease, which is apparent on the morphology and the anatomy of anthers and vascularization of stamens, seems to occur separately within each genus and shall be related to a sort of pollinator. The study of reproductive biology has shown some morphological characteristics in P. pusilla that allow spontaneous self-pollination, such as large pores and the arrangement of the stamens of the flower at anthesis. It can be concluded that P. pusilla is self-compatible and that spontaneous self-pollination happens due to the large pore which faces the stigma at anthesis. It is also remarkable, in this species, the independence of biotic factors during pollination and probably over fruits spreading, which culminate in a highly adapted species to survive in environments with scarce pollinators. Considering this scenario, we conclude that all androecium and anthers variations of these species seem to be associated with a general tendency of pollinators in this family, aforementioned for representatives of the Miconieae tribe. 2014-02-24T00:00:00Z https://repositorio.ufu.br/handle/123456789/50185 Title: Polinização de Peixotoa tomentosa A. Juss. (Malpighiaceae), como as estruturas florais condicionam a visitação biótica e o transporte polínico Abstract: Plant populations have undergone substantial changes over time due to anthropogenic and climatic factors. Angiosperms are the largest and most diverse plant group and have, accordingly, established extensive mutualistic interactions with insects. In the Cerrado, plant–insect interactions are highly diverse, and among the most relevant in this context are those involving the family Malpighiaceae, one of the 11 botanical families that produce floral oils. We investigated how floral morphology in one of its species, Peixotoa tomentosa A. Juss., affects bee visitation and fruit set, considering its capacity to produce fruit through agamospermy. The study was conducted in a Cerrado fragment at Itororó Park Club (formerly Clube de Caça e Pesca Itororó), in Uberlândia, Minas Gerais, Brazil. We assessed floral attractiveness to small-, medium-, and large-bodied bees and the resulting fruit set, and tested five controlled pollination treatments. Visitation rate was lower than expected, with only 10 bees recorded over 15 hours of observation, which limited the evaluation of the floral attraction and fruit set hypotheses; this did not, however, preclude comparison among pollination treatments, whose fruit set values were statistically similar, indicating reproductive capacity even in the absence of pollen grains. Although the adhesive function of staminodes has previously been reported in other plant families, our study provides the first confirmation of this function within Malpighiaceae, showing that the substance exuded by the staminodes significantly increases pollen grain adherence to the transport vector and, subsequently, to the stigmas. Studies on the chemical composition of the staminodal secretion may help elucidate its adhesive function. These results suggest a relationship between low pollinator frequency, prior anthropogenic disturbance (e.g., the 2021 fire), and reduced fruit set, reinforcing the importance of long-term studies on pollination in the Cerrado. 2026-07-23T00:00:00Z https://repositorio.ufu.br/handle/123456789/47773 Title: Regeneração natural em fragmentos de cerrado sensu stricto: padrões ecológicos e aspectos silviculturais de Eugenia involucrata como uma espécie-alvo Abstract: The cerrado sensu stricto, formerly the most extensive phytophysiognomy of the Cerrado biome, has undergone intense conversion to agriculture and livestock production, resulting in fragmentation and varying levels of environmental disturbance. In this context, the present study aimed to characterize the structural patterns of the woody community, evaluete the natural regeneration potential in three fragments (F1, F2, and F3), analyze the regenerative status of Eugenia involucrata and investigate the initial growth and morphophysiological traits of its seedlings under nursery and experimental conditions. Natural regeneration was sampled in two plot classes: tem plots of 10 × 10 m (Class I) and tem plots of 2 × 2 m (Class II), arranged along transects perpendicular to the drainage line. For each species, density, frequency, and the Total Natural Regeneration index (RNT) were calculated, with RNT also determined separately for E. involucrata. A total of 501 regenerating individuals were recorded in F1, 321 in F2, and 153 in F3. The most conserved fragment (F1) exhibited greater species richness and density, with Fabaceae, Myrtaceae, and Malpighiaceae being the most prominent. In F2, Fabaceae, Myrtaceae, Chrysobalanaceae, and Connaraceae were most representative in Class I, while in F3, Fabaceae, Anacardiaceae, Annonaceae, Chrysobalanaceae, and Myrtaceae predominated across both classes. Species such as Miconia albicans, E. involucrata, Matayba guianensis, and Connarus suberosus showed the highest RNT values, indicating strong natural regeneration potential under contrasting environmental conditions. The occurrence of exclusive species across fragments highlighted environmental heterogeneity and differing responses to disturbance. E. involucrata accounted for 113 individuals across the three fragments, with significant differences in density and consistently high RNT values, confirming its robust regenerative performance. Early development of the species in the nursery was examined through two experiments. Experiment I (Matrix) used seeds from three mother trees originating from two fragments, resulting in three treatments (M1, M2, and M3). Height, stem diameter, leaf number, fresh and dry biomass of shoots and roots, MSPA/MSR ratio, Dickson Quality Index (DQI), leaf area, mesophyll structure, stomatal conductance, and chlorophyll content were evaluated at 180 and 300 days. Significant differences among treatments indicated variation in seedling vigor, likely associated with genetic or environmental differences among matrices. In Experiment II (Sun and Shade), seedlings were subjected to full sunlight or shading for 30 days. Only chlorophyll content differed significantly between treatments, although all seedlings exhibited similar growth patterns and high survival rates, highlighting the species’ marked physiological plasticity in response to light availability. Overall, the results demonstrate that E. involucrata possesses high plasticity and strong natural regeneration capacity, reinforcing its suitability for ecological restoration programs in degraded cerrado sensu stricto areas. 2021-08-26T00:00:00Z https://repositorio.ufu.br/handle/123456789/47766 Title: Estratégias de defesa contra a megafauna extinta em fitofisionomias do Cerrado brasileiro Abstract: This study investigates the influence of the extinct South American megafauna on plant anti- herbivory defenses across different vegetation types of the Cerrado biome. We hypothesized that the nature and prevalence of defensive strategies are determined by the interaction between resource availability, particularly soil fertility, and historical herbivory pressures exerted by megafauna. To test this, we compiled functional trait data for woody species of the South American tropical flora from published literature, including leaf size, wood density, specific leaf area, leaf nitrogen, spinescence, and latescence. These data were combined with indicator species lists for savanna, dystrophic “cerradão” forest, mesotrophic “cerradão” forest, deciduous forest, semideciduous forest, and evergreen forest, and analyzed in relation to environmental conditions. Statistical analyses included Principal Component Analysis (PCA) of environmental variables across vegetation types and Bayesian hierarchical regression models for plant defensive traits. Our results show that Cerrado plant defenses arise from the interaction between current environmental conditions and the evolutionary legacy of herbivory. In fertile soils, such as those of deciduous forests, physical defenses predominate, characterized by reduced leaves and high spine density, protecting nutrient-rich tissues from large herbivores. In savannas, low leaf nutritional quality functions as the main defense mechanism, without reliance on small leaves or high spinescence. Dystrophic “cerradão” forest exhibited increased latex production and dense leaves, indicating chemical and structural defenses against smaller herbivores. These findings confirm that plant defenses in the Cerrado are heterogeneous and shaped by its mosaic of vegetation types: fertile environments favor physical defenses protecting nutritious leaves, whereas nutrient-poor environments promote chemical and structural strategies adapted to herbivory by smaller fauna. Overall, this study highlights the combined role of historical and contemporary factors in shaping plant defensive traits in the Cerrado. 2025-08-29T00:00:00Z