Navegando por Autor "Rodrigues, Simone M."
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Item Arabidopsis and tobacco plants ectopically expressing the soybean antiquitin-like ALDH7 gene display enhanced tolerance to drought, salinity, and oxidative stress(Journal of Experimental Botany, 2006-01-23) Rodrigues, Simone M.; Andrade, Maxuel O.; Gomes, Ana Paula Soares; DaMatta, Fabio M.; Baracat-Pereira, Maria C.; Fontes, Elizabeth P.B.Despite extensive studies in eukaryotic aldehyde dehydrogenases, functional information about the ALDH7 antiquitin-like proteins is lacking. A soybean antiquitin homologue gene, designated GmTP55, has been isolated which encodes a dehydrogenase motif-containing 55 kDa protein induced by dehydration and salt stress. GmTP55 is closely related to the stress-induced plant antiquitin-like proteins that belong to the ALDH7 family. Transgenic tobacco (Nicotiana tabacum) and Arabidopsis (Arabidopsis thaliana) plants constitutively expressing GmTP55 have been obtained in order to examine the physiological role of this enzyme under a variety of stress conditions. Ectopic expression of GmTP55 in both Arabidopsis and tobacco conferred tolerance to salinity during germination and to water deficit during plant growth. Under salt stress, the germination efficiency of both transgenic tobacco and Arabidopsis seeds was significantly higher than that of their control counterparts. Likewise, under progressive drought, the transgenic tobacco lines apparently kept the shoot turgidity to a normal level, which contrasted with the leaf wilt phenotype of control plants. The transgenic plants also exhibited an enhanced tolerance to H2O2- and paraquat-induced oxidative stress. Both GmTP55-expressing Arabidopsis and tobacco seeds germinated efficiently in medium supplemented with H2O2, whereas the germination of control seeds was drastically impaired. Similarly, transgenic tobacco leaf discs treated with paraquat displayed a significant reduction in the necrotic lesions as compared with control leaves. These transgenic lines also exhibited a lower concentration of lipid peroxidation-derived reactive aldehydes under oxidative stress. These results suggest that antiquitin may be involved in adaptive responses mediated by a physiologically relevant detoxification pathway in plants.Item Unraveling new genes associated with seed development and metabolism in Bixa orellana L. by expressed sequence tag (EST) analysis(Molecular Biology Reports, 2010-06-19) Rodrigues, Simone M.; Soares, Virgı́nia L. F.; Oliveira, Tahise M. de; Queiroz, Talisson O. de; Lima, Lı́via S.; Hora-Júnior, Braz T.; Gramacho, Karina P.; Micheli, Fabienne; Cascardo, Júlio C. M.; Otoni, Wagner C.; Gesteira, Abelmon S.; Costa, Marcio G. C.The tropical tree Bixa orellana L. produces a range of secondary metabolites which biochemical and molecular biosynthesis basis are not well understood. In this work we have characterized a set of ESTs from a non-normalized cDNA library of B. orellana seeds to obtain information about the main developmental and metabolic processes taking place in developing seeds and their associated genes. After sequencing a set of randomly selected clones, most of the sequences were assigned with putative functions based on similarity, GO annotations and protein domains. The most abundant transcripts encoded proteins associated with cell wall (prolyl 4-hydroxylase), fatty acid (acyl carrier protein), and hormone/flavonoid (2OG-Fe oxygenase) synthesis, germination (MADS FLC-like protein) and embryo development (AP2/ERF transcription factor) regulation, photosynthesis (chlorophyll a–b binding protein), cell elongation (MAP65-1a), and stress responses (metallothionein- and thaumatin-like proteins). Enzymes were assigned to 16 different metabolic pathways related to both primary and secondary metabolisms. Characterization of two candidate genes of the bixin biosynthetic pathway, BoCCD and BoOMT, showed that they belong, respectively, to the carotenoid-cleavage dioxygenase 4 (CCD4) and caffeic acid O-methyltransferase (COMT) families, and are up-regulated during seed development. It indicates their involvement in the synthesis of this commercially important carotenoid pigment in seeds of B. orellana. Most of the genes identified here are the first representatives of their gene families in B. orellana.