Mitochondrial complex II (succinate dehydrogenase [SDH]) plays roles both in the tricarboxylic acid cycle and the respiratory electron transport chain. In Arabidopsis (Arabidopsis thaliana), its flavoprotein subunit is encoded by two nuclear genes, SDH1-1 and SDH1-2. Here, we characterize heterozygous SDH1-1/sdh1-1 mutant plants displaying a 30% reduction in SDH activity as well as partially silenced plants obtained by RNA interference. We found that these plants displayed significantly higher CO 2 assimilation rates and enhanced growth than wild-type plants. There was a strong correlation between CO 2 assimilation and stomatal conductance, and both mutant and silenced plants displayed increased stomatal aperture and density. By contrast, no significant differences were found for dark respiration, chloroplastic electron transport rate, CO 2 uptake at saturating concentrations of CO 2 , or biochemical parameters such as the maximum rates of carboxylation by Rubisco and of photosynthetic electron transport. Thus, photosynthesis is enhanced in SDH-deficient plants by a mechanism involving a specific effect on stomatal function that results in improved CO 2 uptake. Metabolic and transcript profiling revealed that mild deficiency in SDH results in limited effects on metabolism and gene expression, and data suggest that decreases observed in the levels of some amino acids were due to a higher flux to proteins and other nitrogen-containing compounds to support increased growth. Strikingly, SDH1-1/ sdh1-1 seedlings grew considerably better in nitrogen-limiting conditions. Thus, a subtle metabolic alteration may lead to changes in important functions such as stomatal function and nitrogen assimilation.

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Background: Gibberellins (GA 3 ) are the most sprayed growth regulator for table grape production worldwide, increasing berry size of seedless varieties through pericarp cell expansion. However, these treatments also exacerbate berry drop, which has a detrimental effect on the postharvest quality of commercialized clusters. Several studies have suggested that pedicel stiffening caused by GA 3 would have a role in this disorder. Nevertheless, transcriptional and phenotypic information regarding pedicel responses to GA 3 is minimal.Results: Characterization of responses to GA 3 treatments using the lines L23 and Thompson Seedless showed that the former was up to six times more susceptible to berry drop than the latter. GA 3 also increased the diameter and dry matter percentage of the pedicel on both genotypes. Induction of lignin biosynthesis-related genes by GA 3 has been reported, so the quantity of this polymer was measured. The acetyl bromide method detected a decreased concentration of lignin 7 days after GA 3 treatment, due to a higher cell wall yield of the isolated fractions of GA 3treated pedicel samples which caused a dilution effect. Thus, an initial enrichment of primary cell wall components in response to GA 3 was suggested, particularly in the L23 background. A transcriptomic profiling was performed to identify which genes were associated with these phenotypic changes. This analysis identified 1281 and 1787 genes differentially upregulated by GA 3 in L23 and cv. Thompson Seedless, respectively. Concomitantly, 1202 and 1317 downregulated genes were detected in L23 and cv. Thompson Seedless (FDR < 0.05). Gene ontology analysis of upregulated genes showed enrichment in pathways including phenylpropanoids, cell wall metabolism, xylem development, photosynthesis and the cell cycle at 7 days post GA 3 application. Twelve genes were characterized by qPCR and striking differences were observed between genotypes, mainly in genes related to cell wall synthesis. Conclusions: High levels of berry drop are related to an early strong response of primary cell wall synthesis in the pedicel promoted by GA 3 treatment. Genetic backgrounds can produce similar phenotypic responses to GA 3 , although there is considerable variation in the regulation of genes in terms of which are expressed, and the extent of transcript levels achieved within the same time frame.

Commonly, in the transmission network expansion planning (TNEP) problem, the objective is to define the minimal-cost investment in new transmission devices, e.g., the transmission lines and transformers, for the system to operate adequately in a planning horizon. In addition to the traditional approach of considering the installation of new components, the presented model considers the enhancement of the system operation performance through the modification of its topology in each operation scenario. �is modification is made by switching off the lines that degrade the system's performance. By using an illustrative example, we discuss why congestion is eliminated by switching off specific lines from the system, thereby improving the performance of the existing network and constructed candidate lines and leading to lower investment costs. �e proposed method also considers a strategy to reduce the number of lines switched off in order to improve the reliability of the system and avoid alternative optimal solutions with unnecessary lines switched. �e tests are carried out using the 46-bus southern Brazilian system and the IEEE 24-bus system, which are usually used as benchmarks for the TNEP problem. �e results are compared with the solu

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Background Gibberellins (GA3) are the most sprayed growth regulator for table grape production worldwide, increasing berry size of seedless varieties through pericarp cell expansion. However, these treatments also exacerbate berry drop, which has a detrimental effect on the postharvest quality of commercialized clusters. Several studies have suggested that pedicel stiffening caused by GA3 would have a role in this disorder. Nevertheless, transcriptional and phenotypic information regarding pedicel responses to GA3 is minimal. Results Characterization of responses to GA3 treatments using the lines L23 and Thompson Seedless showed that the former was up to six times more susceptible to berry drop than the latter. GA3 also increased the diameter and dry matter percentage of the pedicel on both genotypes. Induction of lignin biosynthesis-related genes by GA3 has been reported, so the quantity of this polymer was measured. The acetyl bromide method detected a decreased concentration of lignin seven days after GA3 treatment, due to a higher cell wall yield of the isolated fractions of GA3-treated pedicel samples which caused a dilution effect. Thus, an initial enrichment of primary cell wall components in response to GA3 was suggested, particularly in the L23 background. A transcriptomic profiling was performed to identify which genes were associated with these phenotypic changes. This analysis identified 1,281 and 1,787 genes differentially upregulated by GA3 in L23 and cv. Thompson Seedless, respectively. Concomitantly, 1,202 and 1,317 downregulated genes were detected in L23 and cv. Thompson Seedless (FDR≤0.05). Gene ontology analysis of upregulated genes showed enrichment in pathways including phenylpropanoids, cell wall metabolism, xylem development, photosynthesis and the cell cycle at seven days post GA3 application. Twelve genes were characterized by qPCR and striking differences were observed between genotypes, mainly in genes related to cell wall synthesis. Conclusions High levels of berry drop are related to an early strong response of primary cell wall synthesis in the pedicel promoted by GA3 treatment. Genetic backgrounds can produce similar phenotypic responses to GA3, although there is considerable variation in the regulation of genes in terms of which are expressed, and the extent of transcript levels achieved within the same time frame.

Background Gibberellins (GA3) are the most sprayed growth regulator for table grape production worldwide, increasing berry size of seedless varieties through pericarp cell expansion. However, these treatments also exacerbate berry drop, which has a detrimental effect on the postharvest quality of commercialized clusters. Several studies have suggested that pedicel stiffening caused by GA3 would have a role in this disorder. Nevertheless, transcriptional and phenotypic information regarding pedicel responses to GA3 is minimal.Results Characterization of responses to GA3 treatments using the lines L23 and Thompson Seedless showed that the former was up to six times more susceptible to berry drop than the latter. GA3 also increased the diameter and dry matter percentage of the pedicel on both genotypes. Induction of lignin biosynthesis-related genes by GA3 has been reported, so the quantity of this polymer was measured. The acetyl bromide method detected a decreased concentration of lignin seven days after GA3 treatment, due to a higher cell wall yield of the isolated fractions of GA3 -treated pedicel samples which caused a dilution effect. Thus, an initial enrichment of primary cell wall components in response to GA3 was suggested, particularly in the L23 background.A transcriptomic profiling was performed to identify which genes were associated with these phenotypic changes. This analysis identified 1,281 and 1,787 genes differentially upregulated by GA3 in L23 and cv. Thompson Seedless, respectively. Concomitantly, 1,202 and 1,317 downregulated genes were detected in L23 and cv. Thompson Seedless (FDR≤0.05). Gene ontology analysis of upregulated genes showed enrichment in pathways including phenylpropanoids, cell wall metabolism, xylem development, photosynthesis and the cell cycle at seven days post GA3 application. Twelve genes were characterized by qPCR and striking differences were observed between genotypes, mainly in genes related to cell wall synthesis.Conclusions High levels of berry drop are related to an early strong response of primary cell wall synthesis in the pedicel promoted by GA3 treatment. Genetic backgrounds can produce similar phenotypic responses to GA3 , although there is considerable variation in the regulation of genes in terms of which are expressed, and the extent of transcript levels achieved within the same time frame.