Plantas acumuladoras de alumínio: panorama global e estudo ecofisiológico em quatro espécies de Melastomataceae nativas da Amazônia

Abstract

Plants that accumulate aluminium (Al) have the ability to grow in soils with high levels of this element in ionized form, a condition that is generally toxic to most plants in acidic environments. These species have aroused interest due to their relevance to ecophysiological processes and their potential for biotechnological innovations in the management of acidic soils, especially in regions where soil acidity is a limiting factor for agriculture. In Brazil, studies on these plants have focused on the Brazilian savannah, leaving significant gaps in other biomes, such as the Amazon. Thus, this work aims to investigate the global state of the art on Al-accumulating plants, map their geographical distribution at an international and national level and analyze the accumulation of the metal in four species of the Melastomataceae family native to the Brazilian Amazon. The dissertation was structured in two chapters. The first used scientometric and systematic review approaches with data collected from the Web of Science and Scopus databases, using search terms such as “plants”, “hyperaccumulat*”, “Al accumulat*” and “tolerant plants”. A total of 862 documents were identified, of which 129 met the eligibility criteria. The results show that scientific production is concentrated in China (31.49%), Japan (24.40%) and Brazil (20.47%), with an emphasis on physiology (67.71% of publications). Al-accumulating plants belong to 68 botanical families, 94.14% of which are Angiosperms, predominantly in tropical regions of Asia and America. The second chapter involved scientific expeditions to Boca do Iriri and Terra do Meio Ecological Station, in the municipality of Altamira-PA, to identify Al-accumulating species among individuals of Melastomataceae. Leaf and soil samples were collected from six 500 x 5 m transects in non-flooded forest. The anatomical, histochemical and chemical analyses revealed that the four species studied show hyperaccumulation of Al, with average levels varying between 17,256.63 mg/kg and 30,660.93 mg/kg of Al in the dry matter, with the highest value recorded in Miconia affinis DC. The record of Al accumulation in M. affinis and Miconia chrysophyilla (Rich) Urb. is the first recorded in this study. Aluminum was found stored in the cell wall of the epidermis, collenchyma and palisade parenchyma of the four species analyzed. However, only one of the histochemical tests was able to detect the presence of Al in the tissues of Bellucia grossularioides (L.) Triana. Thus, this study expands knowledge about Al-accumulating plants and points to the importance of expanding research in the Amazon, contributing to the sustainable management of acidic soils and the conservation of the world's largest tropical rainforest.