Biologia Vegetal
URI permanente desta comunidadehttps://locus.ufv.br/handle/123456789/11836
Navegar
58 resultados
Resultados da Pesquisa
Item An L,L- diaminopimelate aminotransferase mutation leads to metabolic shifts and growth inhibition in Arabidopsis(Journal of Experimental Botany, 2018-12-01) Cavalcanti, João Henrique F.; Kirma, Menny; Barros, Jessica A. S.; Quinhones, Carla G.S.; Pereira- Lima, Ítalo A.; Obata, Toshihiro; Nunes- Nesi, Adriano; Galili, Gad; Fernie, Alisdair R.; Avin- Wittenberg, Tamar; Araújo, Wagner L.Lysine (Lys) connects the mitochondrial electron transport chain to amino acid catabolism and the tricarboxylic acid cycle. However, our understanding of how a deficiency in Lys biosynthesis impacts plant metabolism and growth remains limited. Here, we used a previously characterized Arabidopsis mutant (dapat) with reduced activity of the Lys biosynthesis enzyme L,L-diaminopimelate aminotransferase to investigate the physiological and metabolic impacts of impaired Lys biosynthesis. Despite displaying similar stomatal conductance and internal CO2 concentration, we observed reduced photosynthesis and growth in the dapat mutant. Surprisingly, whilst we did not find differences in dark respiration between genotypes, a lower storage and consumption of starch and sugars was observed in dapat plants. We found higher protein turnover but no differences in total amino acids during a diurnal cycle in dapat plants. Transcriptional and two-dimensional (isoelectric focalization/SDS-PAGE) proteome analyses revealed alterations in the abundance of several transcripts and proteins associated with photosynthesis and photorespiration coupled with a high glycine/serine ratio and increased levels of stress-responsive amino acids. Taken together, our findings demonstrate that biochemical alterations rather than stomatal limitations are responsible for the decreased photosynthesis and growth of the dapat mutant, which we hypothesize mimics stress conditions associated with impairments in the Lys biosynthesis pathway.Item Sucrose breakdown within guard cells provides substrates for glycolysis and glutamine biosynthesis during light- induced stomatal opening(The Plant Journal, 2018-05) Medeiros, David B.; Souza, Leonardo Perez; Antunes, Werner C.; Araújo, Wagner L.; Daloso, Danilo M.; Fernie, Alisdair R.Sucrose has long been thought to play an osmolytic role in stomatal opening. However, recent evidence supports the idea that the role of sucrose in this process is primarily energetic. Here we used a combination of stomatal aperture assays and kinetic [U- 13 C]-sucrose isotope labelling experiments to confirm that sucrose is degraded during light-induced stomatal opening and to define the fate of the C released from sucrose breakdown. We additionally show that addition of sucrose to the medium did not enhance light- induced stomatal opening. The isotope experiment showed a consistent 13 C enrichment in fructose and glu- cose, indicating that during light-induced stomatal opening sucrose is indeed degraded. We also observed a clear 13 C enrichment in glutamate and glutamine (Gln), suggesting a concerted activation of sucrose degra- dation, glycolysis and the tricarboxylic acid cycle. This is in contrast to the situation for Gln biosynthesis in leaves under light, which has been demonstrated to rely on previously stored C. Our results thus collectively allow us to redraw current models concerning the influence of sucrose during light-induced stomatal open- ing, in which, instead of being accumulated, sucrose is degraded providing C skeletons for Gln biosynthesis.Item Self-pruning acts synergistically with diageotropica to guide auxin responses and proper growth form(Plant Physiology, 2018-04) Silva, Willian B.; Vicente, Mateus H.; Robledo, Jessenia M.; Reartes, Diego S.; Ferrari, Renata C.; Bianchetti, Ricardo; Araújo, Wagner L.; Freschi, Luciano; Peres, Lázaro E. P.; Zsögön, AgustinThe SELF PRUNING (SP) gene is a key regulator of growth habit in tomato (Solanum lycopersicum). It is an ortholog of TERMINAL FLOWER1, a phosphatidylethanolamine-binding protein with antiflorigenic activity in Arabidopsis (Arabidopsis thaliana). A spontaneous loss-of-function mutation (sp) has been bred into several industrial tomato cultivars, as it produces a suite of pleiotropic effects that are favorable for mechanical harvesting, including determinate growth habit, short plant stature, and simultaneous fruit ripening. However, the physiological basis for these phenotypic differences has not been thoroughly explained. Here, we show that the sp mutation alters polar auxin transport as well as auxin responses, such as gravitropic curvature and elongation of excised hypocotyl segments. We also demonstrate that free auxin levels and auxin-regulated gene expression patterns are altered in sp mutants. Furthermore, diageotropica, a mutation in a gene encoding a cyclophilin A protein, appears to confer epistatic effects with sp. Our results indicate that SP affects the tomato growth habit at least in part by influencing auxin transport and responsiveness. These findings suggest potential novel targets that could be manipulated for controlling plant growth habit and improving productivity.Item Modulation of auxin signalling through DIAGETROPICA and ENTIRE differentially affects tomato plant growth via changes in photosynthetic and mitochondrial metabolism(Plant, Cell & Environment, 2019-02) Batista‐ Silva, Willian; Medeiros, David B.; Rodrigues‐ Salvador, Acácio; Daloso, Danilo M.; Omena‐ Garcia, Rebeca P.; Oliveira, Franciele Santos; Pino, Lilian Ellen; Peres, Lázaro Eustáquio Pereira; Nunes‐ Nesi, Adriano; Fernie, Alisdair R.; Zsögön, Agustín; Araújo, Wagner L.Auxin modulates a range of plant developmental processes including embryogenesis, organogenesis, and shoot and root development. Recent studies have shown that plant hormones also strongly influence metabolic networks, which results in altered growth phenotypes. Modulating auxin signalling pathways may therefore provide an opportunity to alter crop performance. Here, we performed a detailed physiological and metabolic characterization of tomato (Solanum lycopersicum) mutants with either increased (entire) or reduced (diageotropica—dgt) auxin signalling to investigate the consequences of altered auxin signalling on photosynthesis, water use, and primary metabolism. We show that reduced auxin sensitivity in dgt led to anatomical and physiological modifications, including altered stomatal distribution along the leaf blade and reduced stomatal conductance, resulting in clear reductions in both photosynthesis and water loss in detached leaves. By contrast, plants with higher auxin sensitivity (entire) increased the photosynthetic capacity, as deduced by higher Vcmax and Jmax coupled with reduced stomatal limitation. Remarkably, our results demonstrate that auxin‐sensitive mutants (dgt) are characterized by impairments in the usage of starch that led to lower growth, most likely associated with decreased respiration. Collectively, our findings suggest that mutations in different components of the auxin signalling pathway specifically modulate photosynthetic and respiratory processes.Item Insights into ABA-mediated regulation of guard cell primary metabolism revealed by systems biology approaches(Progress in Biophysics and Molecular Biology, 2018) Medeiros, David B.; Araújo, Wagner L.; Yoshida, Takuya; Anjos, Letícia dos; Fernie, Alisdair R.; Daloso, Danilo M.Despite the fact that guard cell abscisic acid (ABA) signalling pathway is well documented, our understanding concerning how and to which extent ABA regulates guard cell metabolism remains fragmentary. Here we have adopted different systems approaches to investigate how ABA modulates guard cell central metabolism by providing genes that are possibly ABA-regulated. By using previous published Arabidopsis guard cell transcript profiling data, we carried out an extensive co-expression network analysis using ABA-related genes and those related to the metabolism and transport of sugars, starch and organic acids. Next, we investigated the presence of ABA responsive elements (ABRE) in the promoter of genes that are highly expressed in guard cells, responsive to ABA and co-expressed with ABA-related genes. Together, these analyses indicated that 44 genes are likely regulated by ABA and 8 of them are highly expressed in guard cells in both the presence and absence of ABA, including genes of the tricarboxylic acid cycle and those related to sucrose and hexose transport and metabolism. It seems likely that ABA may modulate both sucrose transport through guard cell plasma membrane and sucrose metabolism within guard cells. In this context, genes associated with sucrose synthase, sucrose phosphate synthase, trehalose-6-phosphate, invertase, UDP-glucose epimerase/pyrophosphorylase and different sugar transporters contain ABRE in their promoter and are thus possibly ABA regulated. Although validation experiments are required, our study highlights the importance of systems biology approaches to drive new hypothesis and to unravel genes and pathways that are regulated by ABA in guard cells.Item Extending the ecological distribution of Desmonostoc genus: proposal of Desmonostoc salinum sp. nov., a novel Cyanobacteria from a saline–alkaline lake(International Journal of Systematic and Evolutionary Microbiology, 2018) Alvarenga, Luna Viggiano de; Vaz, Marcelo Gomes Marçal Vieira; Genuário, Diego Bonaldo; Esteves- Ferreira, Alberto A.; Almeida, Allan V. Martins; Castro, Naira Valle de; Lizieri, Claudineia; Souza, José João L. L.; Schaefer, Carlos Ernesto G. R.; Nunes- Nesi, Adriano; Araújo, Wagner L.Cyanobacteria is an ancient phylum of oxygenic photosynthetic microorganisms found in almost all environments of Earth. In recent years, the taxonomic placement of some cyanobacterial strains, including those belonging to the genus Nostoc sensu lato, have been reevaluated by means of a polyphasic approach. Thus, 16S rRNA gene phylogeny and 16S–23S internal transcribed spacer (ITS) secondary structures coupled with morphological, ecological and physiological data are considered powerful tools for a better taxonomic and systematics resolution, leading to the description of novel genera and species. Additionally, underexplored and harsh environments, such as saline–alkaline lakes, have received special attention given they can be a source of novel cyanobacterial taxa. Here, a filamentous heterocytous strain, Nostocaceae CCM-UFV059, isolated from Laguna Amarga, Chile, was characterized applying the polyphasic approach; its fatty acid profile and physiological responses to salt (NaCl) were also determined. Morphologically, this strain was related to morphotypes of the Nostoc sensu lato group, being phylogenetically placed into the typical cluster of the genus Desmonostoc. CCM-UFV059 showed identity of the 16S rRNA gene as well as 16S–23S secondary structures that did not match those from known described species of the genus Desmonostoc, as well as distinct ecological and physiological traits. Taken together, these data allowed the description of the first strain of a member of the genus Desmonostoc from a saline–alkaline lake, named Desmonostoc salinum sp. nov., under the provisions of the International Code of Nomenclature for algae, fungi and plants. This finding extends the ecological coverage of the genus Desmonostoc, contributing to a better understanding of cyanobacterial diversity and systematics.Item Bundle sheath extensions affect leaf structural and physiological plasticity in response to irradiance(Plant, Cell & Environment, 2018) Barbosa, Maria Antonia M.; Chitwood, Daniel H.; Azevedo, Aristéa A.; Araújo, Wagner L.; Ribeiro, Dimas M.; Peres, Lázaro E. P.; Martins, Samuel C. V.; Zsögön, AgustinCoordination between structural and physiological traits is key to plants' responses to environmental fluctuations. In heterobaric leaves, bundle sheath extensions (BSEs) increase photosynthetic performance (light‐saturated rates of photosynthesis, Amax) and water transport capacity (leaf hydraulic conductance, Kleaf). However, it is not clear how BSEs affect these and other leaf developmental and physiological parameters in response to environmental conditions. The obscuravenosa (obv) mutation, found in many commercial tomato varieties, leads to absence of BSEs. We examined structural and physiological traits of tomato heterobaric and homobaric (obv) near‐isogenic lines grown at two different irradiance levels. Kleaf, minor vein density, and stomatal pore area index decreased with shading in heterobaric but not in homobaric leaves, which show similarly lower values in both conditions. Homobaric plants, on the other hand, showed increased Amax, leaf intercellular air spaces, and mesophyll surface area exposed to intercellular airspace (Smes) in comparison with heterobaric plants when both were grown in the shade. BSEs further affected carbon isotope discrimination, a proxy for long‐term water‐use efficiency. BSEs confer plasticity in traits related to leaf structure and function in response to irradiance levels and might act as a hub integrating leaf structure, photosynthetic function, and water supply and demand.Item The role of amino acid metabolism during abiotic stress release(Plant, Cell & Environment, 2019) Batista‐ Silva, Willian; Heinemann, Björn; Rugen, Nils; Nunes‐ Nesi, Adriano; Araújo, Wagner L.; Braun, Hans‐ Peter; Hildebrandt, Tatjana M.Plant responses to abiotic stress include various modifications in amino acid metabolism. By using a hydroponic culture system, we systematically investigate modification in amino acid profiles and the proteome of Arabidopsis thaliana leaves during initial recovery from low water potential or high salinity. Both treatments elicited oxidative stress leading to a biphasic stress response during recovery. Degradation of highly abundant proteins such as subunits of photosystems and ribosomes contributed to an accumulation of free amino acids. Catabolic pathways for several low abundant amino acids were induced indicating their usage as an alternative respiratory substrate to compensate for the decreased photosynthesis. Our results demonstrate that rapid detoxification of potentially detrimental amino acids such as Lys is a priority during the initial stress recovery period. The content of Pro, which acts as a compatible osmolyte during stress, was adjusted by balancing its synthesis and catabolism both of which were induced both during and after stress treatments. The production of amino acid derived secondary metabolites was up‐regulated specifically during the recovery period, and our dataset also indicates increased synthesis rates of the precursor amino acids. Overall, our results support a tight relationship between amino acid metabolism and stress responses.Item Modifications in organic acid profiles during fruit development and ripening: correlation or causation?(Frontiers in Plant Science, 2018-11) Batista- Silva, Willian; Nascimento, Vitor L.; Medeiros, David B.; Nunes- Nesi, Adriano; Ribeiro, Dimas M.; Zsögön, Agustín; Araújo, Wagner L.The pivotal role of phytohormones during fruit development and ripening is considered established knowledge in plant biology. Perhaps less well-known is the growing body of evidence suggesting that organic acids play a key function in plant development and, in particular, in fruit development, maturation and ripening. Here, we critically review the connection between organic acids and the development of both climacteric and non-climacteric fruits. By analyzing the metabolic content of different fruits during their ontogenetic trajectory, we noticed that the content of organic acids in the early stages of fruit development is directly related to the supply of substrates for respiratory processes. Although different organic acid species can be found during fruit development in general, it appears that citrate and malate play major roles in this process, as they accumulate on a broad range of climacteric and non-climacteric fruits. We further highlight the functional significance of changes in organic acid profile in fruits due to either the manipulation of fruit-specific genes or the use of fruit-specific promoters. Despite the complexity behind the fluctuation in organic acid content during fruit development and ripening, we extend our understanding on the importance of organic acids on fruit metabolism and the need to further boost future research. We suggest that engineering organic acid metabolism could improve both qualitative and quantitative traits of crop fruits.Item Downregulation of the δ-subunit reduces mitochondrial ATP synthase levels, alters respiration, and restricts growth and gametophyte development in Arabidopsis(The Plant Cell, 2012-07) Nunes-Nesi, Adriano; Geisler, Daniela A.; Päpke, Carola; Obata, Toshihiro; Matthes, Annemarie; Schneitz, Kay; Maximova, Eugenia; Araújo, Wagner L.; Fernie, Alisdair R.; Persson, StaffanThe mitochondrial ATP synthase (F1Fo complex) is an evolutionary conserved multimeric protein complex that synthesizes the main bulk of cytosolic ATP, but the regulatory mechanisms of the subunits are only poorly understood in plants. In yeast, the δ-subunit links the membrane-embedded Fo part to the matrix-facing central stalk of F1. We used genetic interference and an inhibitor to investigate the molecular function and physiological impact of the δ-subunit in Arabidopsis thaliana. Delta mutants displayed both male and female gametophyte defects. RNA interference of delta resulted in growth retardation, reduced ATP synthase amounts, and increased alternative oxidase capacity and led to specific long-term increases in Ala and Gly levels. By contrast, inhibition of the complex using oligomycin triggered broad metabolic changes, affecting glycolysis and the tricarboxylic acid cycle, and led to a successive induction of transcripts for alternative respiratory pathways and for redox and biotic stress-related transcription factors. We conclude that (1) the δ-subunit is essential for male gametophyte development in Arabidopsis, (2) a disturbance of the ATP synthase appears to lead to an early transition phase and a long-term metabolic steady state, and (3) the observed long-term adjustments in mitochondrial metabolism are linked to reduced growth and deficiencies in gametophyte development.