Karla Menezes-e-Vasconcelos's research while affiliated with University of São Paulo and other places

Plants from Brazilian tropical grasslands of the cerrado biome (also referred to as the Cerrado region) are characterized by the possessing of belowground bud-bearing organs that may be of stem or root origin that enhance the likelihood of surviving a dry season or fire. The root-derived bud bank is referred to when speaking about adventitious sprouting from roots. Root buds or root sprouts allow rapid regrowth after a disturbance or a period of adverse climatic conditions and have the potential to generate clonal populations. Adventitious sprouting from roots is well known to occur in Brazil in perennial species, mainly woody plants. In the present study, we investigate the occurrence of adventitious buds on roots of the annual species Siphanthera arenaria (DC.) Cogn., which is endemic to the Serra do Espinhaço range in Brazil and grows in an area of the cerrado biome. Shoots emerging from the root system of S. arenaria were assessed in a microscopic analysis and classified as reparative-type buds emerging from the cortical parenchyma. The presence of root buds in Siphantera arenaria represents the first record for the Melastomataceae family in the cerrado biome and also the first record of a root bud in an annual species for this biome.

In the prevailing savanna formations of the Cerrado biome, several plants show special morphological and anatomical features, such as cork bark, a thickened underground system and bud-forming underground structure. These traits have been considered to have evolved in distinct lineages as adaptations to drought, fire, or nutrient-deficient soils. Among the 28 recognized species of Homalolepis Turcz. (Simaroubaceae), 20 species occur in drier habitats, as semiarid Caatinga, Cerrado and Restinga. Due to different habitats, a variety of either small geophytic shrubs or large trees can be found in this family. The geoxylic species are characterized by a woody underground perennial axis and a less persistent aerial system that can regrow. However, studies including its morphology and anatomy are lacking in the literature. In the present study, morphology and anatomy of the underground system of five geoxylic species of Homalolepis occurring in the Brazilian Cerrado were investigated. Our results show that all species have xylopodia (upper region) associated with tuberous roots (lower region), and possibly have a sympodial branching from the news shoots, originating from the axillary buds, which were covered by cataphylls. The gemmiferous potential of the xylopodia associated to its tissue parenchyma, with nutrient reserve (starch), and tuberous roots, with wide storage xylematic parenchyma tissue, are important features in the regeneration of aerial organs after drought and fire occurrence. This study then evaluates the possible relation between characteristics of the underground systems found within two taxonomic sections of Homalolepis, as well to the evolution of the geoxylic life-form in the Cerrado lineages of the genus.