Artigos
URI permanente para esta coleçãohttps://locus.ufv.br/handle/123456789/11846
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Item Differential root and shoot responses in the metabolism of tomato plants exhibiting reduced levels of gibberellin(Environmental and Experimental Botany, 2019-01) Martins, Auxiliadora O.; Omena-Garcia, Rebeca P.; Oliveira, Franciele S.; Silva, Welder A.; Hajirezaei, Mohammad-Reza; Vallarino, José G.; Ribeiro, Dimas Mendes; Fernie, Alisdair R.; Nunes-Nesi, Adriano; Araújo, Wagner L.The ability to adapt to the environment is crucial for plant survival and thus a refined communication system capable of integrating endogenous and exogenous signals and further relaying this information to different parts of the plant is a key component of such adaptability. Given that they grow in highly distinct environments it is arguably unsurprising that roots and shoots display different responses to a given environmental condition. Accordingly, a higher sensitivity of roots to gibberellins (GAs) allows rapid adjustments in growth and development possibly triggering (a) stress tolerance mechanism(s). Here we investigated the differential metabolic responses between root and shoot following reductions of the endogenous GA content using tomato (Solanum lycopersicum L.) plants deficient in GA biosynthesis (gib3, moderately deficient, gib2, intermediate deficiency and gib1, extremely deficient in GAs). GA depletion impedes shoot growth to a greater extent than root growth in all mutants. Moreover, the greater the reduction in GA content the greater the extent of a disturbance at the metabolic level. Low leaf carbohydrate contents were observed in plants displaying higher root growth, suggesting an enhanced flow of photoassimilate to support root growth. Large increases in amino acids contents of either roots or shoot were observed. The increased amino acid content was coupled to reduced levels of TCA cycle intermediates suggesting that these changes are directly linked to early reactions of nitrogen assimilation. The combined data are discussed in terms of our current understanding of the interaction between GA and primary metabolism and their crosstalk in environmental responses.Item Increased urea availability promotes adjustments in C/N metabolism and lipid content without impacting growth in Chlamydomonas reinhardtii(Metabolomics, 2019-03) Batista, Aline D.; Rosa, Rinamara M.; Machado, Mariana; Magalhães, Alan S.; Shalaguti, Bárbara A.; Gomes, Priscilla F.; Covell, Lidiane; Vaz, Marcelo G. M. V.; Araújo, Wagner L.; Nunes-Nesi, AdrianoThe use of urea as a nitrogen (N) source by Chlorophytes usually enhances biomass and lipid production when compared to ammonium (NH4+). However, the metabolic shifts displayed byChlamydomonas reinhardtii growing with this organic N source are not known. This study aimed: (i) to characterize the metabolism of C. reinhardtii cultivated in media containing only urea as N source as well as combined with different NH4+ ratios; (ii) to understand how metabolism respond to urea availability. Specific quantification of metabolites using 96-well microplates, and high-performance liquid chromatography combined with non-targeted metabolite profiling by gas chromatography (GC)–time-of-flight (TOF)-mass spectrometry (MS) were used in this study. In addition, GC analysis was used to determine fatty acid profiling. The use of urea did not alter the growth rate in comparison with NH4+. Interestingly, the cell number decreased and the cell size increased proportionally with urea availability. Furthermore, chlorophyll, protein and lipid contents increased with the amount of urea. Regarding the fatty acid profile, oleic acid (C18:1 w8) decreased with amount of urea, while linoleic acid (C18:2 w6) doubled in urea-containing medium. These results indicate that urea promotes remarkable adjustments in metabolism, without drastic changes in biomass, promoting changes in carbohydrate and amino acid metabolism, as well as in lipids production and fatty acid profile.Item The role of silicon in metabolic acclimation of rice plants challenged with arsenic(Environmentaland Experimental Botany, 2015-11-14) Sanglard, Lílian M.V.P.; Detmann, Kelly C.; Martins, Samuel C.V.; Teixeira, Rodrigo A.; Pereira, Lucas F.; Sanglard, Matheus L.; Fernie, Alisdair R.; Araújo, Wagner L.; DaMatta, Fábio M.Silicon (Si) plays key roles in alleviating various abiotic stresses, including arsenic (As) toxicity, via physiological mechanisms that remain poorly understood. Here, we combined photosynthetic measurements with analyses of central metabolism and gene expression to explore the consequences of As-related alterations on primary metabolism and examined whether these consequences could be affected by the application of Si to rice (Oryza sativa L.) plants challenged with As but supplemented with Si. The negative effects of As on photosynthesis and carbohydrate status were largely reversed by Si. However, no major metabolic reprogramming was observed, as denoted by minor, if any, significant changes in (i) the activities of a range of enzymes associated with C metabolism; (ii) the levels of a wide range of organic acids and amino acids; and (iii) the pools of NAD(P)H/NAD(P)+ and the redox states of ascorbate and glutathione. Arsenic toxicity was apparently unrelated to oxidative stress. We suggested that the search for As-tolerant plants under real field conditions should not focus solely on oxidative stress, and hence the focus on photosynthesis might be of higher significance. In conclusion, we identified Si nutrition as a central player that restricts photosynthetic impairment in As-treated plants, in addition to limiting As uptake via modulation of the expression of genes with prime importance in As uptake and translocation.Item Growth inhibition by selenium is associated with changes in primary metabolism and nutrient levels in Arabidopsis thaliana(Plant, Cell and Environment, 2016-06-25) Ribeiro, Dimas M.; Silva Júnior, Dalton D.; Cardoso, Flávio Barcellos; Martins, Auxiliadora O.; Silva, Welder A.; Nascimento, Vitor L.; Araújo, Wagner L.Although Selenium (Se) stress is relatively well known for causing growth inhibition, its effects on primary metabolism remain rather unclear. Here, we characterized both the modu- lation of the expression of specific genes and the metabolic adjustments in Arabidopsis thaliana in response to changes in Se level in the soil. Se treatment culminated with strong inhibition of both shoot and root growth. Notably, growth inhibition in Se‐treated plants was associated with an incom- plete mobilization of starch during the night. Minor changes in amino acids levels were observed in shoots and roots of plants treated with Se whereas the pool size of tricarboxylic acid (TCA) cycle intermediates in root was not altered in response to Se. By contrast, decreased levels of organic acids involved in the first part of the TCA cycle were observed in shoots of Se‐treated plants. Furthermore, decreased expression levels of expansins and endotransglucosylases/endohydrolases (XHTs) genes were observed after Se treatment, coupled with a significant decrease in the levels of essential elements. Collec- tively, our results revealed an exquisite interaction between energy metabolism and Se‐mediated control of growth in Arabidopsis thaliana to coordinate cell wall extension, starch turnover and the levels of a few essential nutrients.Item Photosynthetic and metabolic acclimation to repeated drought events play key roles in drought tolerance in coffee(Journal of Experimental Botany, 2017-05-25) Menezes-Silva, Paulo E.; Sanglard, Lilian M. V. P.; Ávila, Rodrigo T.; Morais, Leandro E.; Martins, Samuel C. V.; Nobres, Priscilla; Patreze, Camila M.; Ferreira, Marcio A.; Araújo, Wagner L.; Fernie, Alisdair R.; DaMatta, Fábio M.Over the last decades, most information on the mechanisms underlying tolerance to drought has been gained by considering this stress as a single event that happens just once in the life of a plant, in contrast to what occurs under natural conditions where recurrent drought episodes are the rule. Here we explored mechanisms of drought toler- ance in coffee (Coffea canephora) plants from a broader perspective, integrating key aspects of plant physiology and biochemistry. We show that plants exposed to multiple drought events displayed higher photosynthetic rates, which were largely accounted for by biochemical rather than diffusive or hydraulic factors, than those submitted to drought for the first time. Indeed, these plants displayed higher activities of RuBisCO and other enzymes associated with car- bon and antioxidant metabolism. Acclimation to multiple drought events involved the expression of trainable genes related to drought tolerance and was also associated with a deep metabolite reprogramming with concordant altera- tions in central metabolic processes such as respiration and photorespiration. Our results demonstrate that plants exposed to multiple drought cycles can develop a differential acclimation that potentiates their defence mechanisms, allowing them to be kept in an ‘alert state’ to successfully cope with further drought events.