RESUMO
Plant resistance to metals can be achieved by two strategies, tolerance and avoidance. Although metal tolerance has been broadly studied in terrestrial plants, avoidance has been less considered as a strategy to cope with soil metal pollution. Avoidance may be an effective alternative in herbaceous plants with connected clonal growth in environments having high heterogeneity in soil micro-spatial distribution of available metals and other soil conditions (i.e. organic matter). In this study, we performed a laboratory experiment on clonal growth of Solidago chilensis when exposed to copper-spiked soils (800â¯mgâ¯kg-1) at different depths (0, 2, 5 and 8â¯cm depth), with (20%) and without addition of organic matter to mimic contrasting microhabitats found at smelter hinterlands (i.e. open bare ground and microhabitats below shrubs). Results showed that plants grown in the 2â¯cm-depth Cu-spiked soils were able to growth and produce ramets and rhizomes. However, increased Cu uptake of plants determined phytotoxic effects and a reduction in clonal spread in the 5â¯cm- and 8â¯cm-depth Cu-spiked soils. Addition of organic matter to the Cu-spiked soil layers allowed clonal spread. Considering that ramet and rhizome production is decreased but not inhibited when copper pollution is restricted to the uppermost soil layer (2â¯cm depth) and that organic matter eliminated soil copper toxicity allowing normal clonal spread, connected clonal growth may be an effective avoidance mechanism of Solidago chilensis, particularly in environments with high heterogeneity in micro-spatial distribution of metals and organic matter in the soil profile and between microhabitats.
Assuntos
Cobre/toxicidade , Poluentes do Solo/toxicidade , Solo/química , Solidago/efeitos dos fármacos , Solidago/crescimento & desenvolvimento , Biodegradação Ambiental , Células Clonais , Cobre/metabolismo , Modelos Teóricos , Rizoma/efeitos dos fármacos , Rizoma/crescimento & desenvolvimento , Rizoma/metabolismo , Poluentes do Solo/metabolismo , Solidago/metabolismoRESUMO
Solidago chilensis Meyen (Asteraceae) is a medicinal important plant with few studies on nutrition and metabolism and none information on cadmium phytotoxicity. The objective of this study was to investigate Cd induced responses on the growth and metabolism in S. chilensis and on arbuscular mycorrhiza (AM). The experiment was carried out in a greenhouse, consisting of a 5 × 4 factorial with five doses of manure (0, 3.5, 7, 14 and 21gdm-3) and four doses of cadmium (0, 25, 50 and 75mgdm-3) applied to a Dystrophic Ultisol. After 250 days of plant cultivation, biomass, nutrient content, photosynthetic rate, guaiacol peroxidase activity, mycorrhizal colonization, glomalin content, anatomical and ultrastucture were evaluated. Plants were significantly affected by interaction of manure and Cd doses with anatomical, ultrastructural, physiological and nutritional modifications. Manure applied into Cd contaminated soil significantly improved mycorrhizal colonization and glomalin production. The highest organic manure dose (21gdm-3) alleviated toxicity symptoms of Cd on S. chilensis.
Assuntos
Cádmio/toxicidade , Esterco , Micorrizas/efeitos dos fármacos , Raízes de Plantas/efeitos dos fármacos , Poluentes do Solo/toxicidade , Solidago/efeitos dos fármacos , Biomassa , Relação Dose-Resposta a Droga , Micorrizas/metabolismo , Micorrizas/ultraestrutura , Fotossíntese/efeitos dos fármacos , Raízes de Plantas/metabolismo , Raízes de Plantas/ultraestrutura , Solo/química , Solo/normas , Solidago/metabolismo , Solidago/ultraestruturaRESUMO
An in vitro culture system leading to the formation of callus and plant regeneration, starting from nodal sections and shoot tips, was developed for Solidago chilensis (Asteraceae). The content of the gastroprotective diterpene solidagenone as well as the phenolics chlorogenic acid (CA) and rutin was determined either in rhizomes from wild growing plants and in callus and in in vitro regenerated plantlets by analytical HPLC. Additionally, total phenolic and flavonoid content was assessed in plant samples, callus and cell suspensions. In terms of dry starting material, the percentual solidagenone content in nine S. chilensis samples ranged from 0.5-3.5% for rhizomes from wild growing plants, 0.1-0.3% for callus and 0.3% for an in vitro regenerated plantlet, respectively. The highest solidagenone contents were found in the wild plant during the late summer in the months of March and April (3.5-2.2%) while highest values for chlorogenic acid (0.5%) and rutin (0.4%) were detected in May, before senescence. The callus tissue and cell suspensions contained some 1.8-2.0 and 1.2% of total phenolics, respectively. CA was the main phenolic in the cell suspension while only traces were found in the callus. Rutin was not detected in the callus nor cell culture.