RESUMO
MAIN CONCLUSION: Blue light exposure delays tomato seed germination by decreasing endosperm-degrading hydrolase activities, a process regulated by CRY1a-dependent signaling and the hormonal balance between ABA and GA. The germination of tomato seeds (Solanum lycopersicum L.) is tightly controlled by an internal hormonal balance, which is also influenced by environmental factors such as light. In this study, we investigated the blue light (BL)-mediated impacts on physiological, biochemical, and molecular processes during the germination of the blue light photoreceptor CRYPTOCHROME 1a loss-of-function mutant (cry1a) and of the hormonal tomato mutants notabilis (not, deficient in ABA) and procera (pro, displaying a GA-constitutive response). Seeds were germinated in a controlled chamber in the dark and under different intensities of continuous BL (ranging from 1 to 25 µmol m-2 s-1). In general, exposure to BL delayed tomato seed germination in a fluency rate-dependent way due to negative impacts on the activities of endosperm-degrading hydrolases, such as endo-ß-mannanase, ß-mannosidase, and α-galactosidase. However, not and pro mutants presented higher germination speed index (GSI) compared to WT despite the BL influence, associated with higher hydrolase activities, especially evident in pro, indicating that the ABA/GA hormonal balance is important to diminish BL inhibition over tomato germination. The cry1a germination percentage was higher than in WT in the dark but its GSI was lower under BL exposure, suggesting that functional CRY1a is required for BL-dependent germination. BL inhibits the expression of GA-biosynthetic genes, and induces GA-deactivating and ABA-biosynthetic genes. The magnitude of the BL influence over the hormone-related transcriptional profile is also dependent upon CRY1a, highlighting the complex interplay between light and hormonal pathways. These results contribute to a better understanding of BL-induced events behind the photoregulation of tomato seed germination.
Assuntos
Endosperma , Solanum lycopersicum , Endosperma/genética , Endosperma/metabolismo , Solanum lycopersicum/genética , Germinação , Sementes/fisiologia , Criptocromos/genética , Criptocromos/metabolismo , beta-Manosidase/genética , beta-Manosidase/metabolismo , Percepção , Ácido Abscísico/metabolismo , Giberelinas/metabolismo , Regulação da Expressão Gênica de PlantasRESUMO
BACKGROUND: Soybean is widely cultivated around the world, including regions with salinity conditions. Salt stress impairs plant physiology and growth, but recent evidence suggests that silicon (Si) is able to mitigate this stressful condition. Therefore, the purpose of this study was to evaluate how different strategies of Si application impact on salt stress tolerance of an intermediate Si accumulator species (soybean). Therefore, we applied four treatments: Si-untreated plants (Si 0); foliar spraying at 20 mmol L-1 (Si F); nutritive solution addition at 2.0 mol L-1 (Si R), and combined foliar spraying at 20 mmol L-1 plus nutritive solution at 2.0 mmol L-1 (Si F + R). We investigated how Si application modified growth, leaf gas exchange, photosynthetic pigments, chlorophyll fluorescence, relative water content (RWC), nutrient accumulation, and ion homeostasis of soybean plants submitted to different levels of salt stress (50 and 100 mmol L-1 NaCl). RESULTS: Salinity induced an expressive reduction in ion accumulation, plant water status, and growth of soybean, while Si application promoted contrary effects and increased potassium (K+ ) accumulation, water status, photosynthetic pigment content, chlorophyll fluorescence parameters, and gas exchange attributes. Additionally, Si application enhanced Si accumulation associated with decreased Na+ uptake and improved morpho-physiological growth. CONCLUSION: The use of exogenous Si can be an efficient strategy to attenuate the harmful effects of salt stress in soybean plants. The best application strategy was observed with combined foliar spraying with Si included in the nutritive solution (Si F + R). © 2023 Society of Chemical Industry.
Assuntos
Glycine max , Silício , Silício/farmacologia , Estresse Salino , Água , ClorofilaRESUMO
The participation of plant cryptochromes in water deficit response mechanisms has been highlighted in several reports. However, the role of tomato (Solanum lycopersicum L.) cryptochrome 1a (cry1a) in the blue light fluence-dependent modulation of the water deficit response remains largely elusive. The tomato cry1a mutant and its wild-type counterpart were grown in water (no stress) or PEG6000 (osmotic stress) treatments under white light (60 µmol m-2 s-1) or from low to high blue light fluence (1, 5, 10, 15 and 25 µmol m-2 s-1). We first demonstrate that under nonstress conditions cry1a regulates seedling growth by mechanisms that involve pigmentation, lipid peroxidation and osmoprotectant accumulation in a blue light-dependent manner. In addition, we further highlighted under osmotic stress conditions that cry1a increased tomato growth by reduced malondialdehyde (MDA) and proline accumulation. Although blue light is an environmental signal that influences osmotic stress responses mediated by tomato cry1a, specific blue light fluence rates are required during these responses. Here, we show that CRY1a manipulation may be a potential biotechnological target to develop a drought-tolerant tomato variety. Nevertheless, the complete understanding of this phenomenon requires further investigation.
Assuntos
Criptocromos/metabolismo , Osmorregulação/genética , Pressão Osmótica , Proteínas de Plantas/metabolismo , Solanum lycopersicum/fisiologia , Luz , Solanum lycopersicum/genéticaRESUMO
Although the blue light photoreceptors cryptochromes mediate the expression of genes related to reactive oxygen species, whether cryptochrome 1a (cry1a) regulates local and long-distance signaling of water deficit in tomato (Solanum lycopersicum L.) is unknown. Thus the cry1a tomato mutant and its wild-type (WT) were reciprocally grafted (WT/WT; cry1a/cry1a; WT/cry1a; cry1a/WT; as scion/rootstock) or grown on their own roots (WT and cry1a) under irrigated and water deficit conditions. Plant growth, pigmentation, oxidative stress, water relations, stomatal characteristics and leaf gas exchange were measured. WT and cry1a plants grew similarly under irrigated conditions, whereas cry1a plants had less root biomass and length and higher tissue malondialdehyde concentrations under water deficit. Despite greater oxidative stress, cry1a maintained chlorophyll and carotenoid concentrations in drying soil. Lower stomatal density of cry1a likely increased its leaf relative water content (RWC). In grafted plants, scion genotype largely determined shoot and root biomass accumulation irrespective of water deficit. In chimeric plants grown in drying soil, cry1a rootstocks increased RWC while WT rootstocks maintained photosynthesis of cry1a scions. Manipulating tomato CRY1a may enhance plant drought tolerance by altering leaf pigmentation and gas exchange during soil drying via local and long-distance effects.
Assuntos
Criptocromos/fisiologia , Proteínas de Plantas/fisiologia , Solanum lycopersicum/fisiologia , Criptocromos/metabolismo , Desidratação , Peróxido de Hidrogênio/metabolismo , Peroxidação de Lipídeos , Solanum lycopersicum/metabolismo , Folhas de Planta/fisiologia , Proteínas de Plantas/metabolismo , Raízes de Plantas/fisiologia , Estômatos de Plantas/fisiologia , Transpiração Vegetal/fisiologia , Solo , Água/metabolismoRESUMO
Recycled paper has the potential to be used as a mulch for vegetable production and can be adopted for the cultivation of Italian zucchini. However, there have been no studies about the water savings or crop coefficient values used in irrigation management in this system; therefore, there is a need for more research. In view of the above, this study aimed to evaluate the effects of recycled paper mulch on evaporation and evapotranspiration in Italian zucchini and to determine the crop coefficients in its developmental stages. The study was carried out in two cultivation cycles conducted at the Lysimetric Station in Viçosa, MG, Brazil. The experiments were installed in a randomized block design with four replicates. Four lysimeter cultivation treatments were applied: without mulch (C); with recycled paper as mulch (CP); with only recycled paper (P); and with Bahia grass (G). Irrigation and drainage measurements were performed daily to calculate the crop and reference evapotranspiration, and thus the crop coefficient (Kc) values. The following characteristics were evaluated: fruit yield, NDVI and water productivity. For the cultivation of Italian zucchini using paper as mulch, Kc values of 0.54, 0.77 and 0.44 and Kcb values of 0.15, 0.45 and 0.18 are recommended for the initial, intermediate and final stages, respectively. NDVI can be used to estimate the Kc values for Italian zucchini. The use of recycled paper as mulch reduces the water consumption of Italian zucchini.
Assuntos
Produção Agrícola/métodos , Cucurbita/crescimento & desenvolvimento , Verduras/crescimento & desenvolvimento , Irrigação Agrícola , Brasil , Cucurbita/metabolismo , Itália , Papel , Transpiração Vegetal , Reciclagem , Solo , Verduras/metabolismo , ÁguaRESUMO
Cadmium (Cd) is probably the most damaging metal to plant species; with a long biological half-life, it can be taken up by plants, disrupting the cell homeostasis and triggering several metabolic pathways. Selenium (Se) improves plant defence systems against stressful conditions, but the biochemical antioxidant responses to Cd stress in tomato plants is poorly understood. To further address the relationship of Cd-stress responses with Se mineral uptake, Cd and Se concentration, proline content, MDA and H2O2 production, and the activity of SOD, APX, CAT and GR enzymes were analyzed in Micro-Tom (MT) plants submitted to 0.5 mM Cd. The results revealed different responses according to Se combination and Cd application. For instance, roots and leaves of MT plants treated with Se exhibited an increase in dry mass and nutritional status, exhibited lower proline content and higher APX and GR activities when compared with plants with no Se application. Plants submitted to 0.5 mM Cd, irrespective of Se exposure, exhibited lower proline, MDA and H2O2 content and higher SOD, CAT and GR activities. Selenium may improve tolerance against Cd, which allowed MT plants exhibited less oxidative damage to the cell, even under elevated Cd accumulation in their tissues. The results suggest that Se application is an efficient management technique to alleviate the deleterious effects of Cd-stress, enhancing the nutritional value and activity of ROS-scavenging enzymes in tomato plants.
Assuntos
Cádmio/toxicidade , Estresse Oxidativo/fisiologia , Selênio/metabolismo , Poluentes do Solo/toxicidade , Solanum lycopersicum/fisiologia , Antioxidantes , Glutationa , Peróxido de Hidrogênio , Oxirredução , Folhas de Planta , Raízes de PlantasRESUMO
Agricultural activities are affected by many biotic and abiotic stresses associated with global climate change. Predicting the response of plants to abiotic stress under future climate scenarios requires an understanding of plant biochemical performance in simulated stress conditions. In this study, the antioxidant response of Panicum maximum Jacq. cv. Mombaça exposed to warming (+2°C above ambient temperature) (eT), water deficit (wS) and the combination eT + wS was analysed under field conditions using a temperature free-air-controlled enhancement facility. Warming was applied during the entire growth period. Data were collected at 13, 19 and 37 days after the start of the water deficit treatment (DAT) and at two sampling times (6:00 and 12:00 h). A significant decrease in chlorophyll was observed under the wS treatment, but an increment in total chlorophyll was observed in eT + wS, particularly at 19 DAT. Significant increase in H2 O2 content, malondialdehyde and protein oxidation was observed in the wS treatment at noon of the third sampling. In the combined wS + eT stress treatment, the activity of the enzymatic antioxidant system increased, particularly of superoxide dismutase (SOD; EC 1.15.1.1) and ascorbate peroxidase (APX; EC 1.11.1.11). The chlorophyll fluorescence images showed that the photochemical performance was not significantly affected by the treatments. In conclusion, under simulated future warming and water stress conditions, the photosystem II (PSII) activity of P. maximum acclimated to moderate warming and a water-stressed environment associated with a relatively favourable antioxidant response, particularly in the activity of APX and SOD.
Assuntos
Antioxidantes/metabolismo , Aquecimento Global , Panicum/metabolismo , Água/metabolismo , Ar , Ascorbato Peroxidases/metabolismo , Fluorescência , Glutationa/metabolismo , Glutationa Redutase/metabolismo , Peróxido de Hidrogênio/metabolismo , Peroxidação de Lipídeos , Malondialdeído/metabolismo , Microclima , Oxirredução , Complexo de Proteína do Fotossistema II/metabolismo , Pigmentos Biológicos/metabolismo , Folhas de Planta/metabolismo , Folhas de Planta/fisiologia , Chuva , Superóxido Dismutase/metabolismo , TemperaturaRESUMO
Fluoxetine (FLX) is a selective serotonin reuptake inhibitor (SSRI) antidepressant widely used in clinics and very often found in environmental samples of urban aquatic ecosystems in concentrations ranging from ng/L to µg/L. Fish populations might be especially susceptible to FLX due to the presence of conserved cellular receptors of serotonin. Neurotoxic effects on fish biota of polluted water bodies may be expected, but there are no sufficient studies in the current literature to elucidate this hypothesis. Batteries of embryo larval assays with zebrafish were performed to evaluate the potential effects of FLX exposure, including environmentally relevant concentrations. Evaluated parameters included survival, development, behaviour and neuronal biochemical markers. Regarding acute toxicity, a 168â¯h-LC50 value of 1.18â¯mg/L was obtained. Moreover, hatching delay and loss of equilibrium were observed, but at a concentration level much higher than FLX measured environmental concentrations (>100⯵g/L). On the other hand, effects on locomotor and acetylcholinesterase activity (≥0.88 and 6⯵g/L, respectively) were found at levels close to the maximum reported FLX concentration in surface waters. Altogether, these results suggest that FLX is neurotoxic to early life stages of zebrafish, in a short period of time causing changes in important ecological attributes which can probably be linked from molecular to population level.
Assuntos
Comportamento Animal/efeitos dos fármacos , Inibidores da Colinesterase/toxicidade , Embrião não Mamífero/efeitos dos fármacos , Desenvolvimento Embrionário/efeitos dos fármacos , Fluoxetina/toxicidade , Proteínas do Tecido Nervoso/antagonistas & inibidores , Poluentes Químicos da Água/toxicidade , Acetilcolinesterase/química , Acetilcolinesterase/metabolismo , Animais , Antidepressivos de Segunda Geração/efeitos adversos , Biomarcadores/metabolismo , Resistência a Medicamentos , Embrião não Mamífero/enzimologia , Larva/efeitos dos fármacos , Larva/enzimologia , Larva/crescimento & desenvolvimento , Dose Letal Mediana , Proteínas do Tecido Nervoso/metabolismo , Concentração Osmolar , Inibidores Seletivos de Recaptação de Serotonina/efeitos adversos , Especificidade da Espécie , Testes de Toxicidade Aguda , Peixe-Zebra/embriologia , Peixe-Zebra/crescimento & desenvolvimento , Proteínas de Peixe-Zebra/antagonistas & inibidores , Proteínas de Peixe-Zebra/metabolismoRESUMO
We characterized the proliferative activity of multi-oocyte follicles with anti-nuclear antigen of proliferating cells (PCNA). Ovaries (n = 12) from heifers were processed for histology. From 789 multi-oocytes follicles observed, only 11 were considered appropriated for immunostaining, since they presented all nuclei of the oocytes clearly visible. All multi-oocyte follicles were positive for PCNA, but some oocytes showed no proliferative activity. We conclude that oocytes in multi-oocyte follicles seem to be in different stages of the cell cycle.
O objetivo deste trabalho foi caracterizar a atividade proliferativa de folículos multi-oócitos com antígeno marcador de proliferação celular (PCNA). Ovários (n = 12) de novilhas foram processados para histologia. A partir de 789 folículos multi-oócitos identificados, somente 11 foram considerados adequados para imunohistoquímica por apresentarem todos os núcleos claramente visíveis. Todos os folículos multi-oócitos foram positivos para PCNA, mas alguns oócitos não apresentaram marcação. Concluímos que oócitos presentes em folículos multi-oócitos parecem estar em diferentes fases do ciclo celular.
Assuntos
Animais , Bovinos , Bovinos/embriologia , Folículo Ovariano/crescimento & desenvolvimento , Folículo Ovariano/fisiologia , Proliferação de Células , OócitosRESUMO
We characterized the proliferative activity of multi-oocyte follicles with anti-nuclear antigen of proliferating cells (PCNA). Ovaries (n = 12) from heifers were processed for histology. From 789 multi-oocytes follicles observed, only 11 were considered appropriated for immunostaining, since they presented all nuclei of the oocytes clearly visible. All multi-oocyte follicles were positive for PCNA, but some oocytes showed no proliferative activity. We conclude that oocytes in multi-oocyte follicles seem to be in different stages of the cell cycle.(AU)
O objetivo deste trabalho foi caracterizar a atividade proliferativa de folículos multi-oócitos com antígeno marcador de proliferação celular (PCNA). Ovários (n = 12) de novilhas foram processados para histologia. A partir de 789 folículos multi-oócitos identificados, somente 11 foram considerados adequados para imunohistoquímica por apresentarem todos os núcleos claramente visíveis. Todos os folículos multi-oócitos foram positivos para PCNA, mas alguns oócitos não apresentaram marcação. Concluímos que oócitos presentes em folículos multi-oócitos parecem estar em diferentes fases do ciclo celular.(AU)