RESUMO
KEY MESSAGE: Overexpression of StCaM2 in tobacco promotes plant growth and confers increased salinity and drought tolerance by enhancing the photosynthetic efficiency, ROS scavenging, and recovery from membrane injury. Calmodulins (CaMs) are important Ca2+ sensors that interact with effector proteins and drive a network of signal transduction pathways involved in regulating the growth and developmental pattern of plants under stress. Herein, using in silico analysis, we identified 17 CaM isoforms (StCaM) in potato. Expression profiling revealed different temporal and spatial expression patterns of these genes, which were modulated under abiotic stress. Among the identified StCaM genes, StCaM2 was found to have the largest number of abiotic stress responsive promoter elements. In addition, StCaM2 was upregulated in response to some of the selected abiotic stress in potato tissues. Overexpression of StCaM2 in transgenic tobacco plants enhanced their tolerance to salinity and drought stress. Accumulation of reactive oxygen species was remarkably decreased in transgenic lines compared to that in wild type plants. Chlorophyll a fluorescence analysis suggested better performance of photosystem II in transgenic plants under stress compared to that in wild type plants. The increase in salinity stress tolerance in StCaM2-overexpressing plants was also associated with a favorable K+/Na+ ratio. The enhanced tolerance to abiotic stresses correlated with the increase in the activities of anti-oxidative enzymes in transgenic tobacco plants. Overall, our results suggest that StCaM2 can be a novel candidate for conferring salt and drought tolerance in plants.
Assuntos
Proteínas de Ligação ao Cálcio/metabolismo , Secas , Nicotiana/genética , Nicotiana/fisiologia , Proteínas de Plantas/metabolismo , Salinidade , Solanum tuberosum/metabolismo , Estresse Fisiológico , Antioxidantes/metabolismo , Proteínas de Ligação ao Cálcio/genética , Calmodulina/genética , Calmodulina/metabolismo , Perfilação da Expressão Gênica , Regulação da Expressão Gênica de Plantas/efeitos dos fármacos , Genoma de Planta , Germinação/efeitos dos fármacos , Germinação/genética , Íons , Membranas , Fotossíntese/efeitos dos fármacos , Reguladores de Crescimento de Plantas/farmacologia , Proteínas de Plantas/genética , Plantas Geneticamente Modificadas , Prolina/metabolismo , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Espécies Reativas de Oxigênio/metabolismo , Sequências Reguladoras de Ácido Nucleico/genética , Plântula/efeitos dos fármacos , Plântula/genética , Plântula/crescimento & desenvolvimento , Estresse Fisiológico/efeitos dos fármacos , Estresse Fisiológico/genética , Nicotiana/enzimologia , Nicotiana/crescimento & desenvolvimento , Fatores de Transcrição/metabolismo , Água/metabolismoRESUMO
The present study was designed to study the growth and yield responses of a tropical potato variety (Solanum tuberosum L. cv. Kufri chandramukhi) to different levels of carbon dioxide (382 and 570ppm) and ozone (50 and 70ppb) in combinations using open top chambers (OTCs). Plants were exposed to three ozone levels in combination with ambient CO2 and two ozone levels at elevated CO2. Significant increments in leaf area and total biomass were observed under elevated CO2 in combination with ambient O3 (ECO2+AO3) and elevated O3 (ECO2+EO3), compared to the plants grown under ambient concentrations (ACO2+AO3). Yield measured as fresh weight of potato also increased significantly under ECO2+AO3 and ECO2+EO3. Yield, however, reduced under ambient (ACO2+AO3) and elevated ozone (ACO2+EO3) compared to ACO2 (filtered chamber). Number, fresh and dry weights of tubers of size 35-50mm and>50mm used for direct consumption and industrial purposes, respectively increased maximally under ECO2+AO3. Ambient as well as elevated levels of O3 negatively affected the growth parameters and yield mainly due to reductions in number and weight of tubers of sizes >35mm. The quality of potato tubers was also modified under different treatments. Starch content increased and K, Zn and Fe concentrations decreased under ECO2+AO3 and ECO2+EO3 compared to ACO2+AO3. Starch content reduced under ACO2+AO3 and ACO2+EO3 treatments compared to ACO2. These results clearly suggest that elevated CO2 has provided complete protection to ambient O3 as the potato yield was higher under ECO2+AO3 compared to ACO2. However, ambient CO2 is not enough to protect the plants under ambient O3 levels. Elevated CO2 also provided protection against elevated O3 by improving the yield. Quality of tubers is modified by both CO2 and O3, which have serious implications on human health at present and in future.
Assuntos
Poluentes Atmosféricos/toxicidade , Dióxido de Carbono/toxicidade , Ozônio/toxicidade , Solanum tuberosum/efeitos dos fármacos , Interações Medicamentosas , Crescimento/efeitos dos fármacos , Clima TropicalRESUMO
The present study was conducted to assess morphological, biochemical and yield responses of palak (Beta vulgaris L. cv Allgreen) to ambient and elevated levels of CO(2) and O(3), alone and in combination. As compared to the plants grown in charcoal filtered air (ACO(2)), growth and yield of the plants increased under elevated CO(2) (ECO(2)) and decreased under combination of ECO(2) with elevated O(3) (ECO(2) + EO(3)), ambient O(3) (ACO(2) + AO(3)) and elevated O(3) (EO(3)). Lipid peroxidation, ascorbic acid, catalase and glutathione reductase activities enhanced under all treatments and were highest in EO(3.) Foliar starch and organic carbon contents increased under ECO(2) and ECO(2) + EO(3) and reduced under EO(3) and ACO(2) + AO(3.) Foliar N content declined in all treatments compared to ACO(2) resulting in alteration of C/N ratio. This study concludes that ambient level of CO(2) is not enough to counteract O(3) impact, but elevated CO(2) has potential to counteract the negative effects of future O(3) level.