RESUMO
Nuclear factor Y (NF-Y) is a ubiquitous transcription factor found in eukaryotes. It is composed of three distinct subunits called NF-YA, NF-YB and NF-YC. NF-Ys have been identified as key regulators of multiple pathways in the control of development and tolerance to biotic and abiotic factors. The present study aimed to identify and characterize the complete repertoire of genes coding for NF-Y in citrus, as well as to perform the functional characterization of one of its members, namely CsNFYA5, in transgenic tobacco plants. A total of 22 genes coding for NF-Y were identified in the genomes of sweet orange (Citrus sinensis) and Clementine mandarin (C. clementina), including six CsNF-YAs, 11 CsNF-YBs and five CsNF-YCs. Phylogenetic analyses showed that there is a NF-Y orthologous in the Clementine genome for each sweet orange NF-Y gene; this was not observed when compared to Arabidopsis thaliana. CsNF-Y proteins shared the same conserved domains with their orthologous proteins in other organisms, including mouse. Analysis of gene expression by RNA-seq and EST data demonstrated that CsNF-Ys have a tissue-specific and stress inducible expression profile. qRT-PCR analysis revealed that CsNF-YA5 exhibits differential expression in response to water deficit in leaves and roots of citrus plants. Overexpression of CsNF-YA5 in transgenic tobacco plants contributed to the reduction of H2O2 production under dehydration conditions and increased plant growth and photosynthetic rate under normal conditions and drought stress. These biochemical and physiological responses to drought stress promoted by CsNF-YA5 may confer a productivity advantage in environments with frequent short-term soil water deficit.
Assuntos
Fator de Ligação a CCAAT/genética , Citrus/genética , Secas , Proteínas de Plantas/genética , Estresse Fisiológico , Arabidopsis/genética , Fator de Ligação a CCAAT/metabolismo , Citrus/metabolismo , Genes de Plantas/genética , Filogenia , Proteínas de Plantas/metabolismo , Plantas Geneticamente Modificadas/genética , Alinhamento de Sequência , Nicotiana/genéticaRESUMO
Erythrina fusca is an important legume used for shade cover in cacao plantations in Brazil. Cacao plantations receive large quantities of copper (Cu)-containing agrochemicals, mainly for control of diseases. Therefore, Cu toxicity was investigated in seedlings grown in hydroponics with increasing concentrations of Cu (0.005-32 mg L-1) in a greenhouse. Ultrastructural analyses showed cell plasmolysis in the root cortical area and changes in thylakoid membranes at 8 mg Cu L-1 and higher. There were changes in epicuticular wax deposition on the leaf surface at the 16 and 32 mg Cu L-1 treatments. Leaf gas exchanges were highly affected 24 hours after application of treatments beginning at 8 mg Cu L-1 and higher Cu concentrations. Chemical analyses showed that Cu content in E. fusca roots increased as Cu concentration in the nutrient solution increased, whereas the shoot did not show significant changes. It is also observed that excess Cu interfered with Zn, Fe, Mn, Mg, K, P, and Ca content in the different E. fusca organs. Investigation of Cu toxicity symptoms focusing on morphophysiological, ultrastructural, gas exchange, and nutritional changes would be useful to alleviate Cu toxicity in E. fusca under field conditions, an important agroforestry species in cacao plantation.
Assuntos
Cobre/toxicidade , Poluentes Ambientais/toxicidade , Erythrina , Biodegradação Ambiental , Brasil , Erythrina/crescimento & desenvolvimento , Erythrina/fisiologia , Raízes de Plantas , PlântulaRESUMO
The aim of the present study was to identify the sites of accumulation of Cr in the species of macrophytes that are abundant in the Cachoeira river, namely, Alternanthera philoxeroides, Borreria scabiosoides, Polygonum ferrugineum and Eichhornia crassipes. Plants were grown in nutritive solution supplemented with 0.25 and 50 mg l(-1) of CrCl(3)·6H(2)O. Samples of plant tissues were digested with HNO(3)/HCl in a closed-vessel microwave system and the concentrations of Cr determined using inductively-coupled plasma mass spectrometry (ICP-MS). The ultrastructure of root, stem and leaf tissue was examined using transmission electron microscopy (TEM) and secondary ion mass spectrometry (SIMS) in order to determine the sites of accumulation of Cr and to detect possible alterations in cell organelles induced by the presence of the metal. Chromium accumulated principally in the roots of the four macrophytes (8.6-30 mg kg(-1) dw), with much lower concentrations present in the stems and leaves (3.8-8.6 and 0.01-9.0 mg kg(-1) dw, respectively). Within root tissue, Cr was present mainly in the vacuoles of parenchyma cells and cell walls of xylem and parenchyma. Alterations in the shape of the chloroplasts and nuclei were detected in A. philoxeroides and B. scabiosoides, suggesting a possible application of these aquatic plants as biomarkers from Cr contamination.
Assuntos
Amaranthaceae , Cromo/farmacologia , Eichhornia , Polygonum , Rubiaceae , Poluentes Químicos da Água/farmacologia , Amaranthaceae/anatomia & histologia , Amaranthaceae/efeitos dos fármacos , Cromo/análise , Eichhornia/anatomia & histologia , Eichhornia/efeitos dos fármacos , Microscopia Eletrônica de Transmissão , Folhas de Planta/química , Folhas de Planta/ultraestrutura , Raízes de Plantas/química , Raízes de Plantas/ultraestrutura , Caules de Planta/química , Caules de Planta/ultraestrutura , Polygonum/anatomia & histologia , Polygonum/efeitos dos fármacos , Rios , Rubiaceae/anatomia & histologia , Rubiaceae/efeitos dos fármacos , Espectrometria de Massa de Íon Secundário , Poluentes Químicos da Água/análiseRESUMO
Cadmium (Cd) originating from atmospheric deposits, from industrial residues and from the application of phosphate fertilizers may accumulate in high concentrations in soil, water and food, thus becoming highly toxic to plants, animals and human beings. Once accumulated in an organism, Cd discharges and sets off a sequence of biochemical reactions and morphophysiological changes which may cause cell death in several tissues and organs. In order to test the hypothesis that Cd interferes in the metabolism of G. americana, a greenhouse experiment was conducted to measure eventual morphophysiological responses and cell death induced by Cd in this species. The plants were exposed to Cd concentrations ranging from 0 to 16 mg l(-1), in a nutritive solution. In TUNEL reaction, it was shown that Cd caused morphological changes in the cell nucleus of root tip and leaf tissues, which are typical for apoptosis. Cadmium induced anatomical changes in roots and leaves, such as the lignification of cell walls in root tissues and leaf main vein. In addition, the leaf mesophyll showed increase of the intercellular spaces. On the other hand, Cd caused reductions in the net photosynthetic rate, stomatal conductance and leaf transpiration, while the maximum potential quantum efficiency of PS2 (Fv/Fm) was unchanged. Cadmium accumulated in the root system in high concentrations, with low translocation for the shoot, and promoted an increase of Ca and Zn levels in the roots and a decrease of K level in the leaves. High concentrations of Cd promoted morphophysiological changes and caused cell death in roots and leaves tissues of G. americana.
Assuntos
Cádmio/farmacologia , Folhas de Planta/efeitos dos fármacos , Raízes de Plantas/efeitos dos fármacos , Rubiaceae/efeitos dos fármacos , Morte Celular/efeitos dos fármacos , Relação Dose-Resposta a Droga , Folhas de Planta/citologia , Folhas de Planta/metabolismo , Raízes de Plantas/citologia , Raízes de Plantas/metabolismo , Teoria Quântica , Rubiaceae/citologia , Rubiaceae/metabolismoRESUMO
This study aimed to evaluate if Parisoschoenus obesulus Casey only attacks naturally aborting coconuts and, consequently, is not a pest of young fruits of coconut tree. Aiming to test this hypothesis, inflorescences at diverse stages of physiological development were offered to individuals of P. obesulus. The results showed that only aborting fruits were colonized by P. obesulus corroborating the established hypothesis.