Acta Physiologiae Plantarum最新文献

The effect of exogenous administration of two concentrations of proline (10 and 20 mM) on postharvest values and chilling injury (CI) of ‘Malaseh Saveh’ pomegranate (Punica granatum L.) fruits was investigated during 90 days at 4 °C. Proline treatment attenuated CI symptoms and prevented membrane lipids peroxidation, and reduction of cell membrane integrity in treated fruits, which were represented by malondialdehyde and electrolyte leakage, respectively. Therewith, a higher amount of endogenous proline (352.48 µg g⁻¹ FW) was perceived in 20 mM proline-treated fruits at the end of the cold storage time. Furthermore, proline treatment increased antioxidant capacity and antioxidant enzyme activity, namely ascorbate peroxidase, superoxide dismutase, and catalase, and also retained ascorbic acid amount at higher levels. This treatment decreased the activity of polyphenol oxidase and enhanced the phenylalanine ammonia-lyase activity which led to high accumulation of total phenol, flavonoids, and anthocyanin. All in all, exogenous application of proline, especially 20 mM concentration, as a safe, natural, and environment-friendly osmolyte substance, could alleviate harmful effects of CI and retain eating values of pomegranate fruits all over long-term postharvest and shelf life.

Boron toxicity is an abiotic stress restricting agricultural production in arid and semiarid parts of the world. This study aimed to investigate the effects of serotonin and melatonin on tomato seedlings under short (5 days) and long-term (8 days) boron toxicity applied as 7.5 mM boric acid in the nutrient solution. Shoot and root lengths, dry weights and water contents, ion leakage levels, malondialdehyde, proline and relative water contents were used as morphological and physiological stress indicators. Expression levels of the enzymatic antioxidative defense genes, FeSOD, CAT2, GR1, APX1, P5CS, ethylene biosynthesis gene ACS2, DEADBOX RNA helicase, and two protein kinase genes CPK2 and MPK3 were also investigated. Melatonin application (10 µM) completely reversed necrotic and chlorotic lesions on leaves, while serotonin application (5 µM) partly ameliorated the visible boron toxicity symptoms. Both indoleamines reduced membrane damage and increased osmoprotectant proline levels under long-term boron toxicity. Exogenous melatonin and serotonin applications also reduced ACS2 gene expression while increasing the transcript levels of CPK2, as well as enzymatic antioxidative defense system genes under long-term boron toxicity. The study showed that both indoleamine compounds interacted with early and late stress responses and successfully mitigated boron toxicity stress in tomato.

In this study, the effect of inoculation with PGPR on growth, sulfur and DL-sulforaphane content of broccoli seedlings was evaluated. Rhizobacterial strains of Bacillus pumilus R44, Pseudomonas tolaasii P61 and P. tolaasii A46 were screened for total indole production and P solubilization. Broccoli seedlings were inoculated with these strains in order to establish a greenhouse experiment. Seedlings were harvested 30 days after inoculation to determine fresh weight, dry weight, root volume, height, and relative chlorophyll content, also S uptake and sulforaphane content. Treatment with PGPR resulted in an increase in almost all the variables evaluated compared to the control. Outstanding results were obtained with the A46 and R44 strains, being 18 and 49% higher for sulforaphane content. P61 was the strain with the best results related to indole production (384% higher than A46), phosphate solubilization (287% higher than A46), and root volume (44% higher than control). There were no significant differences in relative chlorophyll content and sulfur accumulation among the treatments. This is the first work that showed the positive effect of PGPR on sulforaphane content in broccoli seedlings, a compound reported with anticancer activity.

The present study examined the interactive role of hydrogen sulfide (H₂S) and nitric oxide (NO) in alleviation of nickel (Ni) induced toxicity on growth, photosynthetic pigments, PS II photochemistry, and impact on oxidative stress biomarkers and antioxidant defense systems of cyanobacteria, i.e., Nostoc muscorum and Anabaena sp., respectively. To substantiate the potential function of H₂S [as sodium hydrosulfide (NaHS); 8 µM)] and NO [as sodium nitroprusside (SNP); 10 µM] test organisms was exposed under 1 µM Ni stress and distinct physio-biochemical parameters was evaluated. The Ni stress declined the growth (by 19% and 23% in N. muscorum and Anabaena sp. respectively), photosynthetic pigments, photosynthetic oxygen evolution, and imbalanced the values of chlorophyll a fluorescence kinetics parameters (Phi_Po, Psi_o, Phi_Eo, PI_ABS decreased together with Fv/Fo) whereas, energy flux parameters were increased (ABS/RC, TRo/RC, ETo/RC and DIo/RC). The exogenous supplementation of NaHS and SNP significantly reduced reactive oxygen species (ROS) in both the cyanobacteria and induced substantial improvement in growth and photosynthesis under Ni stress. Besides this, under NaHS and SNP treatment the activity of antioxidant enzymes like superoxide dismutase, peroxidase, catalase and glutathione-s-transferase downregulated the level of oxidative biomarkers (superoxide radicals, hydrogen peroxide and malondialdehyde equivalents). Further, the interplay role of H₂S and NO was evaluated using H₂S scavenger [hypotaurine (HT; 20 µM)] and inhibitor [propargylglycine (PAG; 50 µM)] of H₂S and scavenger of NO [2-phenyl-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (PTIO; 20 µM)] and NO inhibitor [NG-nitro-L-arginine methyl ester (L-NAME; 100 µM)]. The present study points towards the combined mechanism with downstream signaling of H₂S on NO mediated response in alleviation of Ni induced toxicity in rice field cyanobacteria.

Low P (LP) levels in leaves can affect their photosynthetic N-use efficiency (PNUE), internal N allocation, and mesophyll conductance to CO₂ (g_m). The changes in leaf internal N allocation and g_m in N-fixing trees and the consequent changes in PNUE under low soil P treatments are not well understood. In this study, we exposed seedlings of Dalbergia odorifera, Erythrophleum fordii (N-fixing trees), Castanopsis hystrix, and Betula alnoides (non-N-fixing trees) to three levels of soil P. The effects were not consistent among species, and LP had no specific effect on N-fixing species. Saturated net CO₂ assimilation rate (A_sat) values in D. odorifera and C. hystrix were remarkably lower under LP than under high P (HP) because C_c in D. odorifera and V_cmax and J_max in C. hystrix were reduced. N_area values in D. odorifera and C. hystrix were also reduced under LP, and the degree of reduction of N_area was larger than that of A_sat, which resulted in decreased PNUE in these species. P_R and g_m in D. odorifera and P_R, P_B, and g_m in C. hystrix significantly decreased under LP and were internal factors affecting the variation in PNUE in these two trees. P_CW was significantly and linearly related to P_R only in C. hystrix, indicating that more N was invested in the cell walls to resist the damage caused by low soil P, at the expense of Rubisco N. Our results showed that soil P deficiency affected leaf N utilization, photosynthetic efficiency, and seedling growth.

Salinity stress adversely affects plant growth and development and causes other stresses, such as osmotic and oxidative stress. Salt-tolerant crops capable of inhabiting salty agricultural land will be useful for farming. Red beet (Beta vulgaris L.) is an economically important plant for high salt tolerance, and also contain rich in valuable ingredients including betacyanins, vitamin, antioxidant, and minerals. Exogenous treatment of chemical components facilitates the improvement of crop productivity under salt stress. N-acetyl-L-cysteine (NAC) derived from cysteine amino acid is a precursor of thiol compounds, an antioxidant, and a chelating agent. The 45-day red beets (Beta vulgaris ‘Scarlet Supreme’, B. vulgaris var. crassa ‘Ruby Queen’) were subjected to three NAC levels (100, 250, and 500 µM) and one salinity level (150 mM NaCl) for 1 week to determine the effect of applications on enzymatic and non-enzymatic antioxidant defense systems by comparing two red beets leaf extracts. NAC treatment in combination with NaCl induced an increase in total phenolic content (TPC), total flavonoid (TF), total betalain, and phenolic acid contents in ‘Ruby Queen’, while these contents decreased under the same conditions in ‘Scarlet Supreme’. The antioxidant capacity values were significantly correlated (P < 0.01) with the TPC content in both red beets. In addition, combination treatment stimulated the activity of some of the antioxidant enzymes in comparison to salt stress alone. The GSH content in the red beets was also enhanced by the combination treatments. Furthermore, TBARS values were negatively correlated with GSH or some AsA–GSH cycle enzyme activities and to some extent with POX activity in the leaves of red beets. These results suggest that NAC treatment alleviated many of the deleterious effects of salt stress in beet leaves, which was achieved by enhancing antioxidant defense system-modulating enzymatic and non-enzymatic antioxidant components.

Acid rain and heavy metal cadmium (Cd) pollution are global environmental problems affecting plants. Plant priming with calcium (Ca) alleviates various environmental stresses. However, the mitigation effect of exogenous Ca on Bermuda grass has not been evaluated under the dual stress of Cd and acid rain. This research was designed to explore the effect of 5 mmol/L Ca on the growth of Bermuda grass seedlings under the combined stress. The results showed that exogenous Ca improved the growth indicators including root length, plant height, stem length, leaf length, root dry weight, stem dry weight, leaf dry weight and total dry weight, reduced the MDA content, and increased the relative chlorophyll content, SOD, POD and CAT activity, and N, P, K contents in different organs. The alleviating effect of exogenous Ca was be limited by acid rain intensity. Exogenous Ca had a significant alleviating effect on plants under combined stress of Cd and pH4.5 acid rain, and promoted the Cd uptake in plants. This research provided a scientific basis for further understanding the positive effects of exogenous Ca on plant growth under the combined stress of Cd and acid rain, and phytoremediation of soil Cd pollution in acid rain areas.

Common bean is a legume with high demand for human consumption and with high protein content on its seeds. The seed filling stage is a crucial step to obtain high-quality seeds with a good level of nutrients. For this, it is necessary for a correct communication between the different seed compartments. Nucleotides are essential components with nitrogen and phosphorous on its molecules, and its metabolism in seed development has not been studied in detail. In this manuscript, we have studied nucleotide metabolism in common bean pods during seed filling stage at pod valves, seed coats, and embryos. Nuclease and ribonuclease activities were assayed as nucleotide-generating enzymes, and nucleotidase, nucleosidase, and allantoinase as nucleotide-degrading activities. Nuclease was predominant in seed coats whereas ribonuclease was equally determined in seed coats and valves, although with differences in the three ribonucleases determined (16, 17, and 19 kDa). Nucleotidase and nucleosidase activities were detected in the three pods parts, and differently to nucleic degrading activities with significant activity in embryos. The relative expression of gene families coding for all these activities (S1 nuclease, S-like T2 ribonuclease, nucleotidase, nucleosidase and allantoinase) in the three pods parts was also studied. We have found the highest level of expression for some members of each family in seed coats. The allantoinase data suggest that nucleotide might be fully degraded in valves and seed coats but not in embryos. Overall, the data presented allow to conclude that there is an intense nucleotide metabolism in fruits during the seed filling stage with an especial involvement of seed coats in the process.

Skewness and kurtosis were analysed using mean data from the F₂ to F₅ generations of three interspecific tomato hybrids, incorporating two feral species: Solanum pimpinellifolium (Currant Tomato) and Solanum lycopersicum var. cerasiformae (Cherry Tomato). The study cantered on three crucial traits impacting fruit yield, with predictions generated through artificial neural networks and multiple linear regression. Plant height (PH), fruit weight (FW) and test weight of seeds (TSW) were identified as the most sensitive traits influencing fruit yield/plant in the Alisa Craig Aft × Solanum pimpinellifolium (Cross 1) and the Berika × Solanum lycopersicum var. cerasiformae (Cross 2). In contrast, fruits per plant (FPP), FW and TSW emerged as the key contributors to fruit yield in the BCT 115 dg × Solanum lycopersicum var. cerasiformae (Cross 3). Skewness and kurtosis distribution suggested complementary gene action with fewer number of segregating genes for PH in Cross 1, FW across all three cross combinations, TSW in Cross 1, and FPP in Cross 3. Duplicate gene action with fewer genes could be predicted for TSW in Cross 2 and Cross 3 while complementary gene action and a greater number of segregating genes were suggested for PH in Cross 2. Moderate-to-high narrow sense heritability was determined for all the characters suggesting phenotypic selection to be rewarding. Isolation of seven promising segregates based on the important yield attributers from three inter-specific hybrids in F₅ generation established the worth of advancing interspecific hybrids. This distinctive and novel breeding method offers exceptional potential for isolating superior tomato segregates through a targeted interspecific breeding programme.

Cryopreservation remains the technology of choice for the long-term preservation of plant germplasm. The current contribution reports on the response of seeds of N. wightii, P. vulgaris and T. indica to cryopreservation in terms of plantlet survival post cryostorage as well as examination of the external morphology of seed coats using scanning electron microscopy (SEM). Survival was determined in Petri dishes in the laboratory as well as in the soil. The results showed differential responses in seeds of the three tested species. In the case of P. vulgaris, exposure to liquid nitrogen (LN) did not adversely affect seedling emergence or characteristics of the seed coat. For N. wightii and T. indica, cracks in the seed coat that were apparent in control seeds, appeared more frequently following exposure to LN. In the case of the former species, this observation did not yield adverse consequences and seed germination rate did actually increase from 5.8 to 85.9% after LN treatment. However, in the case of T. indica, the initial growth rate of seedlings was delayed relative to the control although the germination rate was improved. It is postulated that seeds of T. indica possibly incurred additional damage to other seed components which might have led to delayed recovery.