Membrane Stability Index Research Articles

Foliar application of putrescine alleviates terminal drought stress by modulating water status, membrane stability, and yield- related traits in wheat (Triticum aestivum L.).

Drought stress is one of the major limitations to the growth and yield productivity of cereal crops. It severely impairs the early growing and grain -filling stages of wheat. Therefore, cost- effective and eco-friendly approaches for alleviating drought stress in cereal crops are in high demand. Polyamines, such as putrescine, have a significant effect on improving crop yield under drought- stress conditions. Therefore, the current study was executed with the aim of exploring the significance of putrescine in alleviating drought stress and improving yield- related traits in wheat. Two distinct wheat cultivars (Fakhar-e-Bhakkar and Anaj-2017) were treated with the foliar application of different concentrations (control, 0.5, 1.0, and 1.5 PPM) of putrescine (put) under two moisture conditions (well- watered and terminal drought stress). The results demonstrate that the imposition of terminal drought stress significantly reduces different physiological and yield- related traits of both wheat cultivars. The reduction of relative water content (RWC%), membrane stability index (MSI), leaf area, tillers per plant, biomass yield, number of spikelets per spike, 100-grain weight, grain yield per plant, and straw yield was greater in Anaj-2017 than in Fakhar-e-Bhakkar cultivar. The results further explain that the foliar application of increased concentrations of putrescine from 0.0 to 1.0 PPM gradually improved physiological and yield traits, whereas these traits declined with the application of putrescine at the highest dose (1.5 PPM). The exogenous application of 1.0 PPM putrescine improved the relative water content (19.76%), specific leaf area (41.47%), and leaf area ratio (35.84%) compared with the controlled treatment. A higher grain yield (28.0g plant-1) and 100-grain weight (3.8g) were obtained with the foliar application of 1.0 PPM putrescine compared with controlled treatments. The findings of this study confirm the protective role of putrescine against terminal drought stress. It is therefore recommended to use putrescine at a concentration of 1.0 PPM, which could help alleviate terminal drought stress and attain better wheat yield.

Physiological and gene expression responses involved in teak (Tectona grandis L.) seedlings exposed to osmotic and salt stressors

Teak (Tectona grandis L.) is a forest tree having 2n = 2x = 36 diploid chromosomes. Plants are continually subjected to variety of abiotic stresses due to climate change, which alter their physiological processes and gene expression. The current study sought to examine the physiological and differential gene expression of teak seedlings exposed to abiotic stresses (150mM NaCl and 15% PEG-6000). Chlorophyll content, membrane stability index and relative water content were measured at 0, 2, 7 and 12days after treatment. These parameters were initially numerically reduced, but they were significantly reduced during a longer period of treatment. Seedlings treated with 150mM NaCl displayed more harmful effect on the plant than other treatments. The results showed that variety of stresses significantly affect the physiology of seedlings because they cause membrane damage, ROS generation, chlorophyll degradation, and reduction in water absorption. The gene expression of treated and control seedlings was also evaluated at 12days after treatment. Ten stress-related genes were examined for their differential expression using RT-PCR under applied stress. The stress-treated seedlings' leaves showed an up-regulated expression of the genes MYB-3, HSP-1, BI-1 and CS-2. Up-regulation of the genes confirmed the protective function of these genes in plants under abiotic stress. However, gene expression was affected by treatments, the extent of stress and the species of plant. This study came to the conclusion that physiological parameters could be utilized as marker indices to assess a tree's capability to withstand stress at seedling stage. The up-regulated genes will be further investigated and utilized to validate stress tolerance and susceptible teak seedlings.

Interplay of silymarin and clove fruit extract effectively enhances cadmium stress tolerance in wheat (Triticum aestivum).

Osmoprotectant supplementation can be used as a useful approach to enhance plant stress tolerance. However, the effect of silymarin and clove fruit extract (CFE) on wheat plants grown under cadmium (Cd) stress has not been studied. Wheat seeds were planted in plastic pots filled with ions-free sand. A ½-strength Hoagland's nutrient solution was used for irrigation. Pots were treated with eight treatments thirteen days after sowing: 1) Control, 2) 0.5 mM silymarin foliar application [silymarin], 3) 2% CFE foliar application [CFE], 4) CFE enriched with silymarin (0.24 g silymarin L-1 of CFE) [CFE-silymarin], 5) Watering wheat seedlings with a nutritious solution of 2 mM Cd [Cd]. 6) Cadmium + silymarin, 7) Cadmium + CFE, and 8) Cadmium + CFE-silymarin. The experimental design was a completely randomized design with nine replicates. The Cd stress decreased grain yield, shoot dry weight, leaf area, carotenoids, chlorophylls, stomatal conductance, net photosynthetic rate, transpiration rate, membrane stability index, nitrogen, phosphorus, and potassium content by 66.9, 60.6, 56.7, 23.8, 33.5, 48.1, 41.2, 48.7, 42.5, 24.1, 39.9, and 24.1%, respectively. On the other hand, Cd has an Application of CFE, silymarin, or CEF-silymarin for wheat plants grown under Cd stress, significantly improved all investigated biochemical, morphological, and physiological variables and enhanced the antioxidant enzyme activities. Applying CFE and/or silymarin enhanced plant tolerance to Cd stress more efficiently. Our findings suggest using CFE-silymarin as a meaningful biostimulator for wheat plants to increase wheat plants' tolerance to Cd stress via enhancing various metabolic and physiological processes.

Physiomorphic and molecular-based evaluation of wheat germplasm under drought and heat stress.

Drought and heat stress are potential problems that can reduce wheat yield, particularly during the terminal growth stages in arid and semiarid regions of the world. The current study intended to examine the impact of individual and combined drought and heat stress on the biochemical contents (antioxidant enzymes, proline, soluble proteins, and soluble sugars), physiological parameters (chlorophyll content, cell membrane stability, photosynthesis, stomatal conductance, and transpiration), plant-water relations (relative water content, water potential, osmotic potential, and pressure potential), agronomic traits (flag leaf area, plant height, number of tillers per plant, spike length, grains per spike, and thousand-grain weight), and gene expression (TaHSF1a, TaWRKY-33, TaNAC2L, and TaGASR1) in four different thermostable and drought-tolerant wheat genotypes (i.e., Gold-16, HS-240, Suntop, and Hemai-13) collected from different countries. The tri-replicate experiment was conducted using two factorial arrangements in a randomized complete block design (RCBD). All measured traits, except total soluble sugars, proline, and cell membrane stability index, showed significant reduction under both combined and individual treatments. Furthermore, correlation analysis revealed a significant association between biochemical and physiological characteristics and crop agronomic productivity. Furthermore, principal component analysis (PCA) and heatmap analysis demonstrated significant levels of variation in traits according to the type of stress and nature of wheat genotype. The spectrographs and micrographs generated by scanning electron microscopy for the selected high- and low- tolerance samples revealed clear differences in mineral distribution and starch granulation. All studied genes showed comparatively high levels of relative expression under combined treatments of drought and heat stress in all wheat genotypes, but this expression was the highest in 'Gold-16' followed by 'HS-240', 'Suntop', and 'Hemai-13'. Overall, this study concluded that plants are proactive entities and they respond to stresses at all levels; however, the tolerant plants tend to retain the integrity of their biochemical, physiological, and molecular equilibrium.

Response of varied rice genotypes on cell membrane stability, defense system, physio-morphological traits and yield under transplanting and aerobic cultivation

Aerobic rice cultivation progresses water productivity, and it can save almost 50% of irrigation water compared to lowland rice with the appropriate development of genotypes and management practices. Two field trials were conducted during 2020, and 2021 seasons to determine the validation of different rice varieties under aerobic cultivation based on their plant defense system, physio-morphological traits, stress indices, grain yield, and water productivity. The experiments were designed in a split-plot design with four replications. Two planting methods, transplanting and aerobic cultivation, were denoted as the main plots, and ten rice genotypes were distributed in the subplots. The results revealed that the planting method varied significantly in all measured parameters. The transplanting method with well watering had the highest value of all measured parameters except leaf rolling, membrane stability index, antioxidant, proline, and the number of unfilled grains. EHR1, Giza179 and GZ9399 as well as A22 genotypes a chief more antioxidant defense system that operated under aerobic conditions. Giza179, EHR1, GZ9399, and Giza178 showed high cell membrane stability and subsequently high validation under such conditions, and also showed efficiency in decreasing water consumption and improving water use efficiency. In conclusion, this study proves that Giza179, EHR1, GZ9399, Giza178, and A22 are valid genotypes for aerobic conditions.

Effect of hydrogen sulfide and hydrogen peroxide on growth, yield and nutrient content of broccoli plants grown under saline conditions

Salt stress is one of the most damaging abiotic stresses and is likely to worsen in arid and semi-arid regions under climate change, limiting plant production and reducing crop yields. This study was conducted in an open field in the desert under a saline environment, saline soil (9.68 dS.m−1) and saline irrigation water (7.12 dS.m−1), to evaluate the protective effects of H2O2 and H2S on broccoli, two levels of H2O2 (1, and 2 mmol. L−1), and two levels of sodium hydrosulfide (NaHS), H2S donor (0.1 and 0.2 mmol. L−1). Foliar application of either H2O2 or H2S was effective in mitigating the adverse effects of salt stress on growth and yield of broccoli. Chlorophyll (a and b), carotenoids, and APX were significantly increased in plants sprayed with H2S compared to those sprayed with H2O2, while SOD, POX, and CAT activities were greater in plants sprayed with H2O2. The largest decrease in malondialdehyde (MDA), H2O2, and Na accumulation was observed in plants treated with 0.2 mmol. L−1 H2S. Broccoli yield, nutritional content, and cell membrane stability index (CMSI) were increased with foliar treatments, all foliar treatments yielded larger and heavier broccoli heads than untreated plants. However, plants sprayed with 0.2 mmol. L−1 H2S showed the most promising results, significantly enhancing broccoli yield parameters in terms of head fresh weight (24.5%), head dry weight (19.2%), and head diameter (17.7%), and nutritional content such as vitamin C (16.8%) and total soluble solids (9.9%), as well as, leaf nutrient content in terms of N (21.2%) and K (15.6%), with decreasing sodium content by 20.3%. The results suggest that foliar spraying of H2O2 and H2S could be an effective physiological method to mitigate abiotic stress and improve plant growth and yield.

Effect of Hydrogen Peroxide and Soil Amendments on the Physiological Characteristics of Ranunculus Asiaticus in Saline Soils

This study was conducted in a greenhouse at research station (A) of the College of Agricultural Engineering Sciences - University of Baghdad - Jadiriyah during the autumn season of 2020 to study the impact of exogenous application of hydrogen peroxide and soil amendments (zeolite and Disper osmotic regulator) and their interactions in the physiological traits of the Ranunculus asiaticus L. grown in saline soils. The experiment was carried in a split-split block (2*5*3) according to an RCBD randomized complete block design with three replications and an average of 6 plants in the experimental unit The results showed that the growth of Ranunculus asiaticus L in saline soils caused a significant decrease in the leaf content of relative water content (RWC), membrane stability index (MSI), chlorophyll content. While a significant increase in the leaf content of hydrogen peroxide was observed, and the increase in the electrolytic leaching of the plant is an indicator of oxidative stress. The addition of soil amendments to plants grown under salinity stress caused a significant increase in the leaf content relative to water content, membrane stability, decreased electrolytic leaching, and hydrogen peroxide content. Exogenous application of hydrogen peroxide at a concentration (5 mmol l-1) had a positive effect on most of the physiological characteristics. The interaction between soil amendments and hydrogen peroxide contributed to the avoidance of plants from oxidative stress resulting from the high concentration of effective oxygen radicals (ROS) in the cells of plants exposed to salt stress, and stimulating the activity of the enzymatic and non enzymatic defense system in addition to the increase of chlorophyll and physiological characteristics.

Thermal stress-induced physiological and biochemical alterations in papaya genotypes

Low-temperature stress significantly affects physiological processes inducing plant growth hindrance,and reducing crop productivity. The present study aimed to understand the low-temperature stress inducedphysio-chemical behaviour of five papaya genotypes (Pusa Nanha, Red Lady, P-9-5, P-7-9 and one wild relativespecies Vasconcellea cundinamarcensis). Low temperature stress significantly decreased the canopy gasexchange parameters, relative water content (RWC), membrane stability index (MSI) and chlorophyll contentin all the papaya genotypes, while tending to increase the total soluble sugars, proline and total solubleproteins, although the alterations were genotype-specific. V. cundinamarcensis showed greater tolerance tolow-temperature stress followed by P-9-5 and P-7-9 than other genotypes by maintaining the highest RWC,MSI, total soluble proteins, chlorophyll and proline contents. Our results showed that the chlorophyll content,membrane lipid peroxidation and MSI could be used as the indices for the screening of potential papayagenotypes against cold tolerance.

Identification of simple sequence repeat markers linked to heat tolerance in rice using bulked segregant analysis in F2 population of NERICA-L 44 × Uma.

The damage caused by high temperature is one of the most important abiotic stress affecting rice production. Reproductive stage of rice is highly susceptible to high temperature. The present investigation was undertaken to identify polymorphic microsatellite markers (SSR) associated with heat tolerance. The rice cultivars NERICA- L 44 (heat tolerant) and Uma (heat susceptible) were crossed to generate F1 and F2 populations. The F2 population was subjected to heat stress at >38°C and the 144 F2 plants were evaluated for their tolerance. The results note that the mean of the F2 population was influenced by the tolerant parent with regards to the traits of plant height, membrane stability index, photosynthetic rate, stomatal conductance, evapotranspiration rate, pollen viability, spikelet fertility and 1000 grain weight. Ten each of the extremely susceptible and tolerant plants were selected based on the spikelet fertility percentage. Their DNA was pooled into tolerant and susceptible bulks and Bulked Segregant Analysis (BSA) was carried out using 100 SSR markers to check for polymorphism. The survey revealed a polymorphism of 18% between the parents. RM337, RM10793, RM242, RM5749, RM6100, RM490, RM470, RM473, RM222 and RM556 are some of the prominent markers that were found to be polymorphic between the parents and the bulks. We performed gene annotation and enrichment analysis of identified polymorphic markers. Result revealed that the sequence specific site of that chromosome mostly enriched with biological processes like metabolic pathway, molecular mechanism, and subcellular function. Among that RM337 was newly reported marker for heat tolerance. Expression analysis of two genes corresponds to RM337 revealed that LOP1 (LOC_Os08g01330) was linked to high temperature tolerance in rice. The results demonstrate that BSA using SSR markers is useful in identifying genomic regions that contribute to thermotolerance.

Priming-mediated triggering of antioxidative response to induce drought tolerance in Maize (Zea mays L.)

Drought is a well-known issue in plants and it occurs when plants do not receive enough water to meet their requirements. Hence it alters the metabolic process of the plant, consequently reducing the yield. To overcome the loss of yield under prevailing situations, triggering of the antioxidative defense system is required which can mitigate the impact of drought on plants. The priming chemicals KNO3, Mg(NO3)2 and GA3 were evaluated with hydro-priming to know the mitigative response of priming against drought-induced stress in Maize plants. The morpho-physiological and biochemical parameters were used to evaluate the impact of priming-mediated triggers on the antioxidative response. The results of this work indicate that leaf area index (LAI), crop growth rate (CGR, mg g-1 day-1), total chlorophyll, and chl‘a’ (mg g-1) were recorded maximum in T5 (Mg(NO3)2, 10 mM) while chl ‘b’ in T4 (Mg (NO3)2, 7 mM). The maximum Membrane Stability Index (MSI %) and Membrane Injury Index (MII%) were recorded in T5 and T0 (Control). The osmoregulatory compound proline content (µg g-1) and antioxidative enzyme catalase (nm H2O2 mg-1 min-1) were detected in significantly highest quantity in T3 (KNO3, 15 mM) while the least amount of malondialdehyde (MDA nm g-1) was found under the same treatment. The correlation studies amongst all the parameters reflected that MII % and MDA content (MDA nm g-1) negatively correlated with the remaining parameters studied. This study has reflected that out of all the sources of priming treatments, KNO3 in 15 mM and Mg(NO3)2 in 10 mM has the potential to trigger the antioxidative defense mechanism to mitigate the response of drought in Maize.

Physiological, Biochemical, Anatomical, and Agronomic Responses of Sesame to Exogenously Applied Polyamines under Different Irrigation Regimes

Polyamines (PAs) are plant growth regulators that attenuate the destructive impacts of water deficit on sesame plants, particularly in arid regions under abrupt climate change. Limited information is available on the physiological, biochemical, anatomical, and agronomic responses of sesame to exogenous application of PAs under water deficit under field conditions. Thus, a two-season field trial was carried out to assess the impact of exogenously sprayed spermine (Spm), spermidine (Spd), and putrescine (Put) on physio-biochemical and anatomical parameters and their influences on agronomic performance and crop water productivity of sesame plants. The sesame plants were assessed under three irrigation regimes; full irrigation (100% ETc), mild drought (75% ETc), and severe drought (50% ETc) conditions. Drought stress displayed negative impacts on all evaluated parameters. However, exogenously applied Pas, especially Put, restricted the destructive effects of water deficit. The application of PAs exhibited highly significant enhancement in photosynthetic pigments (chlorophyll a, b, and carotenoids), gas exchange (net photosynthetic rate, stomatal conductance, and rate of transpiration), water relations (relative water content, membrane stability index, excised leaf water retention), and plant nutrient content (N, P, and K) compared to untreated plants, particularly under severe drought stress. Moreover, PA application displayed highly significant amelioration in osmoprotectants (free proline, soluble sugars, α-Tocopherol, ascorbate, and glutathione), and antioxidant enzyme activities (catalase, peroxidase, superoxide dismutase, ascorbate peroxidase, and glutathione reductase). In addition, foliar nourishing with PAs exhibited a highly significant reduction in oxidative stress markers (malondialdehyde, electrolyte leakage, superoxide, and hydrogen peroxide). These positive impacts of PA application under drought stress were reflected in highly significant improvement in anatomical characteristics (midrib length and width, vascular bundle length and width, thickness of phloem, xylem and collenchyma, vessel diameter, and number of xylem rows in midvein bundle), and yield-related traits (plant height, leaf area, number of capsules per plant, 1000-seed weight, seed yield, and oil content). Consequently, exogenous application of PAs (in particular, Put) could be exploited to enhance the crop water productivity and yield traits of sesame plants under low water availability in arid regions.

Exogenous zinc mitigates salinity stress by stimulating proline metabolism in proso millet (Panicum miliaceum L.).

Salinity is one of the most concerning ecological restrictions influencing plant growth, which poses a devastating threat to global agriculture. Surplus quantities of ROS generated under stress conditions have negative effects on plants' growth and survival by damaging cellular components, including nucleic acids, lipids, proteins and carbohydrates. However, low levels of ROS are also necessary because of their role as signalling molecules in various development-related pathways. Plants possess sophisticated antioxidant systems for scavenging as well as regulating ROS levels to protect cells from damage. Proline is one such crucial non-enzymatic osmolyte of antioxidant machinery that functions in the reduction of stress. There has been extensive research on improving the tolerance, effectiveness, and protection of plants against stress, and to date, various substances have been used to mitigate the adverse effects of salt. In the present study Zinc (Zn) was applied to elucidate its effect on proline metabolism and stress-responsive mechanisms in proso millet. The results of our study indicate the negative impact on growth and development with increasing treatments of NaCl. However, the low doses of exogenous Zn proved beneficial in mitigating the effects of NaCl by improving morphological and biochemical features. In salt-treated plants, the low doses of Zn (1 mg/L, 2 mg/L) rescued the negative impact of salt (150mM) as evidenced by increase in shoot length (SL) by 7.26% and 25.5%, root length (RL) by 21.84% and 39.07% and membrane stability index (MSI) by 132.57% and 151.58% respectively.The proline content improved at all concentrations with maximum increase of 66.65% at 2 mg/L Zn. Similarly, the low doses of Zn also rescued the salt induced stress at 200mM NaCl. The enzymes related to proline biosynthesis were also improved at lower doses of Zn. In salt treated plants (150mM), Zn (1 mg/L, 2 mg/L) increased the activity of P5CS by 19.344% and 21%. The P5CR and OAT activities were also improved with maximum increase of 21.66% and 21.84% at 2 mg/L Zn respectively. Similarly, the low doses of Zn also increased the activities of P5CS, P5CR and OAT at 200mM NaCl. Whereas P5CDH enzyme activity showed a decrease of 82.5% at 2mg/L Zn+150mM NaCl and 56.7% at 2mg/L Zn+200 mM NaCl. These results strongly imply the modulatory role of Zn in maintaining of proline pool during NaCl stress.

Morpho-physiological and biochemical attributes as tools to screen tolerance and susceptible rice cultivars for drought stress

Present research work was aimed to observe possible changes in the metabolism of rice plants (Oryza sativa L.) through drought stress. Rice belongs to the family Poaceae. It is considered as a vital food crop across all the major countries worldwide. Rice is prone to be affected by drought stress. Therefore, developing the drought tolerant cultivars of cereal crops assumed considerable importance. This work was carried out with an objective to study the Screening of rice cultivars against water stress and compare biochemical characteristic among different drought tolerant and sensitive rice cultivars. A set of 25 cultivars of rice were screened against drought stress at vegetative stage through various morpho-physiological characters such as moisture, relative water content (RWC), membrane stability index(MSI), membrane injury(MI), seedling length and seedling weight. The RWC is a best criterion for plant water status. The osmotic adjustment is a influential mechanism of conserving cellular hydration under water stress and RWC expression also affects osmotic adjustment in this respect. Thus, it can be considered that the higher RWC having cv. GAR-13 and NWGR-16026 were tolerant and lower RWC having cv. NWGR-16009 and NWGR-16019 were susceptible. Hence, cv. GAR-13 & NWGR-16026 was used as tolerant and NWGR-16009 & NWGR-16019 were used as susceptible. On the basis of first experiment total four cultivars (Two tolerant NWGR-16026 & GAR-13, two susceptible NWGR-16009 & NWGR-16019) were selected for various biochemical analysis. The results indicated that total soluble sugars (TSS), glycine betaine and ascorbic acid content were found significantly higher in cultivar NWGR-16026. The proline content was found significantly higher in cultivar GAR-13. So, RWC and some biochemical parameters are best indicators for selection regarded as potentially useful for drought tolerant rice cultivars and targets for development through transgenic approaches.

In vitro simulation of drought stress in some Iranian Damask rose landraces

Rosa damascena is one of the oldest valuable rose flower varieties that is almost drough tolerant. However, selecting and identifying landraces that are more tolerant to drought conditions will be effective in developing the cultivation of the plant under stress. The most important step in developing drought-tolerant plants is the evaluation and identification of resistant and susceptible genotypes. In this case, an experiment was performed under in vitro conditions using five levels (0, 25, 50, 75, and 100 g/L) of polyethylene glycol (PEG) on four landraces of the Damask rose (Maragheh, Urmia, Pakdasht, and Kashan). Based on the findings, the resistance of the different landraces to a water deficit was measured by the Design-Expert software using the response level (RSM) method. The results showed that Maragheh, with the highest fresh and dry weight, total chlorophyll, chlorophyll a, chlorophyll b, proline and an increase in the superoxide dismutase activity, had a high tolerance to drought stress. Moreover, Maragheh with a decreasing leaf number, height, malondialdehyde, hydrogen peroxide and having a higher membrane stability index, showed a better defence mechanism against oxidative stress than the other landraces. Also, after Maragheh, Pakdasht had the best performance compared to the other two landraces up to 75g/L of PEG, but not as well as Maragheh at the highest level of the tested PEG. Urmia and especially Kashan probably do not have much tolerance to drought stress regarding all the results and levels of desirability.

Plant growth regulators preserved the longevity of cut stems of Chrysanthemum morifolium by orchestrating physio-biochemical and anatomical responses

The marketability of cut flowers is determined by their postharvest quality parameters. Among these parameters, vase life is most crucial and different plant growth regulators (PGRs) play a significant role in regulating vase life. With the objective, to regulate vase life and other quality parameters of commercially important cut stems of chrysanthemum cv. White Star, a study was planned to have an insight into the role of different PGRs in orchestrating underlying physio-biochemical and anatomical responses. Three PGRs viz., Benzyl adenine (50, 100, 150 and 200 μM BA), Thidiazuron (5, 10, 15 and 20 μM TDZ) and Salicylic acid (50, 100, 150 and 200 μM SA) were used as pulsing solution. The results revealed that PGR especially 10 μM TDZ delayed leaf and floret senescence as compared to control. The visual observations (retention of green colour of leaves and white of florets) were correlated to enhanced water absorption, relative water content, membrane stability index, total soluble sugars and total soluble proteins ; higher content of chlorophyll in leaves and lower content of carotenoids and anthocyanins in florets. Further, the antioxidant enzymes (peroxidase and catalase) activities were also higher in PGR-treated stems than in control. These results were further supported by anatomical studies that indicated minimum blockage in xylem and maintenance in turgidity of cells as revealed through the size of tissues (radius of pith) of treated stems (control-118.48 mm and 10 μM TDZ-177.94 mm). Although all PGR concentrations significantly maintained relative water content, membrane stability index, respiratory substrates and antioxidant activity for a longer time, the low concentrations of TDZ had the most relevant impact on longevity. The longevity of stems treated with10 μM TDZ was up to 23 days as compared to 13 days in control. So 10 μM TDZ could be used as a chemical tool to improve chrysanthemum longevity and increase its commercial potential.

Interactive effects of Pseudomonas putida and salicylic acid for mitigating drought tolerance in canola (Brassica napus L.)

This research was designed to analyze the interactive effects of Pseudomonas putida and salicylic acid on the growth of canola in stress and non-stress conditions. Salicylic acid is a phenolic derivative, that has a direct involvement in various plant stages like growth, and inflorescence. While Pseudomonas putida is a drought-tolerant strain having plant growth-promoting characteristics like phosphate solubilization, indole acetic acid, and catalase production. Combined application of Pseudomonas putida and salicylic acid has the ability to develop stress tolerance in plants and also improve growth of plants. They have significant (p < 0.05) effects on germination and morphological, physiological, and biochemical parameters. The plants that received the co-application of Pseudomonas putida and salicylic acid gave more significant results than their alone application. They showed enhanced germination percentage, germination index, promptness index and, seedling vigor index by 19%, 18%, 34% and, 27%, respectively. There was a substantial increase of 25%, 27%, and 39% in shoot length, root length, and leaf area, respectively. The synergistic effect of both treatments has caused a 14% and 12% increase in the Canola plants' relative water content and membrane stability index respectively. A substantial increase of 18% in proline content was observed by the inoculation of Pseudomonas putida, whereas proline content was increased by 28% by the exogenous application of salicylic acid. The content of flavonoids (39%) and phenol (40%) was significantly increased by the co-application. The increase in superoxide dismutase (46%), ascorbate peroxidase (43%), and glutathione (19%) were also significant. The present research demonstrated that the combined application of Pseudomonas putida and salicylic acid induces drought tolerance in canola and significantly improves its growth.

Investigating the Potential of Arbuscular Mycorrhizal Fungi in Mitigating Water Deficit Effects on Durum Wheat (Triticum durum Desf.)

Wheat is one of the main staple cereal crops worldwide. However, drought-induced stress is one of the factors limiting wheat productivity, especially in arid and semi-arid regions. The present study aims to investigate the influence of arbuscular mycorrhizal fungi (AMF) on wheat plant growth under water-deficit conditions. Three Algerian durum wheat varieties—Mohamed Ben Bachir (MBB), Boussellem (BS) and Waha (W)—were grown with (+AMF) or without (−AMF) under water-deficit and non-stress conditions. Morphological, physiological, and biochemical responses to AMF inoculation under water deficit were quantified. The results showed improved morphological parameters (height of the aerial part (HAP), internode length (LIN), aerial part dry weight (APDW), root dry weight (RDW), length of the ear (LE)), and chlorophyll content in AMF-inoculated plants under water-deficit conditions compared to control plants (−AMF). Moreover, soluble protein content (SPC) and membrane stability index (MSI) significantly increased with AMF inoculation under water deficit by 18% and 10%, respectively, while the proline content decreased after AMF inoculation. In addition, the water deficit significantly increases peroxidase (POD), ascorbate peroxidase (APX), and catalase (CAT), but +AMF decreases them considerably in all studied varieties. The results suggest that AMF inoculation can lead to optimized durum wheat production under arid and semi-arid conditions and provide a basis for further studies on its effects under field conditions.

Physiological, biochemical, and postharvest characteristics of two cut rose cultivars are regulated by various supplemental light sources

Light is not only a photosynthetic energy source for biochemically plant cellular accumulation but also the most important signaling messenger for plant growth, development, and environmental adaptations, influencing the postharvest quality and longevity. In this study, to optimize the biochemical and physiological responses of cut rose flowers cv. ‘Jumilia’ and ‘Samurai’ to the different light quality provided by metal halide (MH), high pressure sodium (HPS), and light-emitting diode (LED) lamps and two light intensities of LED (75 and 150 μmol m−2 s−1 PPFD) on the postharvest life. The results showed that flower water content, as well as total carbohydrate, anthocyanin, and carotenoid content, were significantly induced by LED irradiation, but didn't influence the starch content of cut roses. Furthermore, MH and HPS lighting changed the osmotic potential, decreased the membrane stability index, and consequently increased the color change after harvest, resulting in shorter postharvest life of cut roses comparing to the LED environment. More specifically, plants produced by LED lighting reached higher activity of phenylalanine ammonia-lyase (PAL) enzymes and the following higher lignin concentration. LED-exposed rose flowers showed an increase in antioxidant activity and limitation of lipid peroxidation and hydrogen peroxide but were not effective in ascorbate peroxidases (APX) enzyme activity of cut rose flowers. Overall, LED irradiation delayed the senescence of postharvest cut roses mainly by inducting protein biosynthesis, activating the enzymatic system, and inhibiting microbial proliferation. These results suggest that the spectral quality of lighting altered biochemical function, cell wall lignification, and antioxidative defense mechanisms that affect postharvest attributes in roses.

Synergistic Impact of Melatonin and Putrescine Interaction in Mitigating Salinity Stress in Snap Bean Seedlings: Reduction of Oxidative Damage and Inhibition of Polyamine Catabolism

While the individual influences of melatonin (MT) and polyamines (PAs) have been widely studied under various abiotic stresses, little is known about their interaction under salinity stress. In the present study, salt stress applied by 50 mM of sodium chloride (NaCl) on snap bean seedlings has been supplemented with 20 μM of MT and/or 100 μM of putrescine (Put) (individually and in combination). The results indicated that under salinity stress, the combination of MT + Put achieved the highest significant increase in shoot fresh and dry weight, chlorophyll (Chl a), Chl a + b, carotenoids, total soluble sugars, proline, K, Ca, and cell membrane stability index (CMSI), as well as catalase (CAT) and peroxidase (POX) activities. This improvement was associated with an obvious decrease in Na, Na/K ratio, and oxidative damage as indicated by reducing leaf contents of methylglyoxal (MG), hydrogen peroxide (H2O2), and the rate of lipid peroxidation (malondialdehyde; MDA). Moreover, the combination of MT + Put demonstrated a significant decrease in the activities of diamine oxidase (DAO) and polyamine oxidase (PAO) leading to the reduction of the rate of polyamine oxidation. Meanwhile, MT applied individually gave the highest significant increase in leaf relative water content (RWC), Chl b, superoxide dismutase (SOD), and ascorbate peroxidase (APX). Conclusively, the combination treatment of MT + Put could decrease the degradation of polyamines and enhance tolerance to salinity stress in snap bean seedlings.

Elucidating the role of key physio-biochemical traits and molecular network conferring heat stress tolerance in cucumber.

Cucumber is an important vegetable crop grown worldwide and highly sensitive to prevailing temperature condition. The physiological, biochemical and molecular basis of high temperature stress tolerance is poorly understood in this model vegetable crop. In the present study, a set of genotypes with contrasting response under two different temperature stress (35/30°C and 40/35°C) were evaluated for important physiological and biochemical traits. Besides, expression of the important heat shock proteins (HSPs), aquaporins (AQPs), photosynthesis related genes was conducted in two selected contrasting genotypes at different stress conditions. It was established that tolerant genotypes were able to maintain high chlorophyll retention, stable membrane stability index, higher retention of water content, stability in net photosynthesis, high stomatal conductance and transpiration in combination with less canopy temperatures under high temperature stress conditions compared to susceptible genotypes and were considered as the key physiological traits associated with heat tolerance in cucumber. Accumulation of biochemicals like proline, protein and antioxidants like SOD, catalase and peroxidase was the underlying biochemical mechanisms for high temperature tolerance. Upregulation of photosynthesis related genes, signal transduction genes and heat responsive genes (HSPs) in tolerant genotypes indicate the molecular network associated with heat tolerance in cucumber. Among the HSPs, higher accumulation of HSP70 and HSP90 were recorded in the tolerant genotype, WBC-13 under heat stress condition indicating their critical role. Besides, Rubisco S, Rubisco L and CsTIP1b were upregulated in the tolerant genotypes under heat stress condition. Therefore, the HSPs in combination with photosynthetic and aquaporin genes were the underlying important molecular network associated with heat stress tolerance in cucumber. The findings of the present study also indicated negative feedback of G-protein alpha unit and oxygen evolving complex in relation to heat stress tolerance in cucumber. These results indicate that the thermotolerant cucumber genotypes enhanced physio-biochemical and molecular adaptation under high-temperature stress condition. This study provides foundation to design climate smart genotypes in cucumber through integration of favorable physio-biochemical traits and understanding the detailed molecular network associated with heat stress tolerance in cucumber.