ABSTRACT Accidents that occur during the transport of oil and its derivatives have been one of the primary causes of environmental pollution in recent decades. Studies on changes in plant physiology caused by these pollutants are scarce, and the effects on plant metabolism are little known. As such, the aim of the present study was to analyze the effect of soil contaminated with diesel fuel on the physiology of young Hymenaea courbaril L. and Jatropha curcas L. plants. The following variables were analyzed: gas exchanges, photosynthetic pigments, chlorophyll index (SPAD) and protoplasmic damage. The treatments used were: T0 - control (100% of maximum soil water holding capacity - contamination-free soil), T1 and T2 (50% of maximum soil water holding capacity + addition of 23 mL and 46 mL of diesel fuel, respectively) and two assessment times (3h and 192h after contamination). Significant differences in gas exchanges were observed for both species 3h after diesel fuel application. For photosynthetic pigments and the chlorophyll index, increases were found 3h and 192 h after imposed stress, for both species. A significant rise in electrolyte leakage was observed, more pronounced in J. curcas plants after 192h, for treatments T1 and T2 compared to T0. These findings show the potential of species to acclimate themselves to adverse conditions, and should be considered in recovery programs for environments degraded by oil derivatives.
RESUMO Acidentes que ocorrem no processo de transporte do petróleo e de seus derivados têm sido um dos principais motivos de poluição ambiental nas últimas décadas. Pesquisas sobre alterações ocasionadas por estes poluentes na fisiologia de plantas ainda são escassos, sendo pouco conhecidos os efeitos ocasionados no metabolismo vegetal. Diante do exposto, o objetivo do presente estudo foi analisar o efeito do solo contaminado com óleo diesel na fisiologia de plantas jovens de Hymenaea courbaril L. e Jatropha curcas L. As variáveis analisadas foram: trocas gasosas, pigmentos fotossintéticos, índice de clorofila (SPAD) e danos protoplasmáticos. Os tratamentos utilizados foram: T0 - controle (100% da capacidade máxima de retenção de água no solo - solo sem contaminação), T1 e T2 (50% da capacidade máxima de retenção de água no solo + adição de 23 mL e 46 mL de óleo diesel, respectivamente) e 2 épocas de avaliação (3h e 192h após contaminação). Diferenças significativas foram evidenciadas após 3h de aplicação do óleo diesel para as trocas gasosas para ambas as espécies. Para os pigmentos fotossintéticos e o índice de clorofila, foram verificados incrementos após 3h e 192h de imposição do estresse, para as duas espécies. Verificou-se elevados acréscimos para o percentual de vazamento de eletrólitos, sendo mais pronunciando nas plantas de J. curcas, após 192h, para os tratamentos T1 e T2 em relação ao tratamento T0. Estas observações evidenciam o potencial de aclimatação das espécies às condições adversas, devendo ser consideradas em programas de recuperação de ambientes degradados por contaminação com derivados de petróleo.
To evaluate physiological genotypic differences between two Barbados cherry genotypes (13- and 14-CPA) under water deficit, initial growth, water relations, and organic solute accumulation were evaluated in an experiment performed using four-month-old seedlings, which were subjected to four water treatments (100, 75, 50, and 25% of field capacity), with five replications. Severe water deficit (25% of field capacity) negatively affected plant height, stem diameter, leaf area, dry matter of the leaves and stem to both genotypes, and root dry matter to genotype 13-CPA. Predawn (Ywpd) and midday leaf water potentials (Ywmd) were reduced in plants grown under 25% of field capacity, only in the genotype 14-CPA. There was not a change in relative water content, even with the reduction in the leaf water potential. Severe water deficit did not induce organic solutes accumulation, instead it reduced carbohydrate content in leaves of genotypes and aminoacids, proline and proteins, in genotype 13-CPA. In the roots accumulation of all organic solutes studied, it was verified genotype 13-CPA under 25% of field capacity, but only carbohydrates increased in plants under 25% of field capacity to 14-CPA. These results suggest two different mechanisms used by Barbados cherry genotypes to maintain the water status. To the 13-CPA one, the accumulation of soluble organic solutes in the roots is the main mechanism used to maintain the tissue hydration. However, the 14-CPA genotype changed the root to shoot ratio in order to avoid desiccation. Despite the mechanism used by both genotypes, a moderate drought stress does not induce significant morphophysiological changes in Barbados cherry.
Increasing efforts to preserve environmental resources have included the development of more efficient technologies to produce energy from renewable sources such as plant biomass, notably through biofuels and cellulosic residues. The relevance of the soybean industry is due mostly to oil and protein production which, although interdependent, results from coordinated gene expression in primary metabolism. Concerning biomass and biodiesel, a comprehensive analysis of gene regulation associated with cell wall components (as polysaccharides and lignin) and fatty acid metabolism may be very useful for finding new strategies in soybean breeding for the expanding bioenergy industry. Searching the Genosoja transcriptional database for enzymes and proteins directly involved in cell wall, lignin and fatty acid metabolism provides gene expression datasets with frequency distribution and specific regulation that is shared among several cultivars and organs, and also in response to different biotic/abiotic stress treatments. These results may be useful as a starting point to depict the Genosoja database regarding gene expression directly associated with potential applications of soybean biomass and/or residues for bioenergy-producing technologies.