Stomatal Conductance Research Articles

Chloroplast ATP synthase restricts photosynthesis under fluctuating light in tomato but not in maize

Photosynthesis in fluctuating light requires coordinated adjustments of diffusion conductance and biochemical capacity, but the role of chloroplast ATP synthase activity (gH+) in dynamic photosynthesis is not well understood. In this study, we measured gas exchange, chlorophyll fluorescence and electrochromic shift signals in fluctuating light for leaves of tomato (Solanum lycopersicum) and maize (Zea mays). During the transition from sun to shade, simultaneous increases in gH+, effective quantum yield of PSII, and net CO2 assimilation rate (AN) occurred in tomato but uncoupled in maize, indicating that gH+ limited AN during the sun-to-shade transition in tomato but not in maize. During the shade-to-sun transition, gH+ increased simultaneously with stomatal conductance, mesophyll conductance and Rubisco carboxylation capacity in tomato, suggesting that gH+ is an overlooked factor affecting light induction of AN in tomato. By comparison, gH+ maintained at high levels in maize and its AN was mainly restricted by stomatal conductance. Our results reveal that the kinetics of gH+ in fluctuating light differs between species, and chloroplast ATP synthase may be a potential target for improving dynamic photosynthesis in crops such as tomato.

Potencial bioindicador de mudas de Cedrela fissilis em áreas contaminadas por cobre

ABSTRACT Soil contamination with toxic metals brings along severe environmental issues. Among these metals, copper (Cu) is harmful to plant development when it reaches high contamination levels in the soil. Thus, identifying species capable of resisting this contamination type helps these sites’ revegetation and decontamination processes. Therefore, the present study aimed to investigate the tolerance of Cedrela fissilis plants to excess Cu through morphophysiological and biochemical variables. C. fissilis seedlings were subjected to five concentrations of Cu (0, 2, 4, 6, and 8 mg L-1). The experimental design was completely randomized, with five treatments and four repetitions. Morphophysiological (number of leaves, shoot height, root length, dry weight, morphological variables of the root system, and leaf area) and biochemical (antioxidant enzymes, lipid peroxidation, hydrogen peroxide concentration, and photosynthetic pigments) traits and Cu accumulated in roots and shoot were evaluated. High concentrations of Cu had a negative effect on the shoot and root dry weight, photosynthetic rate, stomatal conductance, and transpiration rate. Overall, Cu increased the activity of the antioxidant enzymes and lipid peroxidation. Therefore, Cu incidence in the nutrient solution has negatively influenced the biochemical and physiological traits of C. fissilis seedlings to the detriment of their growth. Thus, it was possible to identify sensitive behavior by the investigated species. Because of these features, C. fissilis seedlings can be used as markers for copper-contaminated areas.

Transfer and biological effects of cadmium along a tomato – thrip – predatory bug food chain

The heavy metal, cadmium (Cd) is an increasingly serious issue in agricultural ecosystems, mediating bottom-up effects on plants, herbivores and natural enemies. We measured how Cd modifies interactions between tomato Solanum lycopersicum, western flower thrips Frankliniella occidentalis, and the predatory bug Orius sauteri by examining Cd effects on the growth of tomato, the fitness of western flower thrips, and the survival and behavior of predators. The photosynthetic parameters of Pn (net photosynthetic rate), Gs (stomatal conductance), Ci (intercellular CO2 concentration), and Tr (transpiration rate) of tomato plants significantly decreased with the increase of Cd concentration. The total survival number of western flower thrips fed on tomato plants treated with different concentrations of Cd was significantly lower than that of the control, and sex ratios (female/male) gradually increased with the increase of Cd concentration. The numbers of thrips predated by O. sauteri on tomato plants treated with high concentrations of Cd (2.0 or 4.0mg/L) were significantly reduced by the second day. Cadmium was accumulated and bioconcentrated in the roots, stems, leaves of tomato plants, and transferred to F. occidentalis, and O. sauteri. Cadmium translocated in significant quantities from roots to the stems and leaves of tomato plants, and from the tomato leaf to F. occidentalis. However, there was minimal (non-significant) transfer of Cd from F. occidentalis to O. sauteri. The presence of Cd significantly reduced the growth of tomato plants, the fitness of F. occidentalis, and the predation efficiency of O. sauteri. Collectively, Cd can mediate bottom-up effects on tomato, thrip, and predatory bug along food chain, potentially interrupting pest biological control in tomato in heavy metal-contaminated ecosystems.

Physiological characteristics of ornamental caladiums (Caladium x hortulanum Birdsey, Araceae Juss.) through leaf color diversity

This work aims to analyze the physiological characteristics of caladium ornamental plants with different leaf colors. Ten leaf colors, i.e., dark maroon, maroon, red, pink, white, pinkish young green, yellow, lime green, pinkish dark green, and dark green, were arranged in a completely randomized design and subjected to colorimetric red–green–blue (RGB) and portable photosynthesis measurement. Caladium leaf color, defined by the colorimetric RGB value, significantly impacted leaf physiological properties. Heatmap analysis apparently clustered caladiums into dark-colored group and light-colored ones. Dark-colored caladiums, as indicated by lower RGB values, exhibited higher photosynthesis rate, stomatal conductance, and water use efficiency (WUE). In contrast, light-colored caladium show a higher RGB, leaf temperature and light use efficiency (LUE) than the dark ones. By considering their leaf color-based physiological adaptability, this work recommends moderate sunlight and adequate water conditions for growing light-colored caladiums, while dark caladiums potentially tolerate excess light and water scarcity. Further research, including quantitative pigment analysis, is necessary to verify this hypothesis.

Triploid Formation and Heat Tolerance of Angelonia angustifolia with Various Ploidy Levels

Angelonia (Angelonia angustifolia), a popular potted flower and bedding plant, often experiences severe wilting or leaf drying during hot summers in tropical and subtropical regions. Polyploidization may enhance the heat tolerance of angelonia plants. In this study, diploid (2x) angelonia ‘Serena Purple’ and ‘Serena White’ were crossed with tetraploid (4x) lines to produce interploidy plants. More seed production was observed from 4x × 2x crosses than from 2x × 4x crosses. Despite observing triploid block in interploidy hybridization, triploid plants were successfully obtained from the interploidy seeds. Growth, flowering, and photosynthesis of diploid, triploid, and tetraploid plants were assessed at day/night temperatures of 30/25 °C and 25/20 °C. All angelonia plants exhibited increased height and stem diameter as well as reduced leaf SPAD-502 value, leaf thickness, flower number, flower length, net photosynthetic rate, and stomatal conductance at 30/25 °C compared with those at 25/20 °C. At 30/25 °C, triploid and tetraploid plants had higher leaf SPAD-502 values, leaf thickness, and net photosynthetic rates than those of diploid plants. Diploid plants had the most branches at 25/20 °C, but their branch and flower numbers decreased the most at 30/25 °C compared with those of triploid and tetraploid plants. Notably, at 30/25 °C, triploid plants exhibited the earliest f lowering and produced the most branches and flowers compared with those of diploid and tetraploid plants.

Mitigating effects of Nigeria seaweed phytonutrients on biochemical and physiological conditions of Lycopersicon esculentum under heavy metal-induced abiotic stress

Abiotic stress has become a significant issue in recent years, affecting various physiological and biochemical aspects of crops and threatening food security. This study aimed to investigate the effects of seaweed on the biochemical and physiological conditions of Lycopersicon esculentum under heavy metal-induced abiotic stress. Lycopersicon esculentum plants were grown in greenhouse bags for four weeks and then exposed to 0.10M Pb Nitrate. They were divided into six groups: one control group sprayed with tap water and five experimental groups sprayed with different seaweed concentrations (0%, 20%, 40%, 60%, and 80%). Results showed that abiotic stress led to notable decreases in root length, shoot length, chlorophyll a, chlorophyll b, stomatal conductance, photosynthetic rate, Rubisco activity, and carotenoids by 48%, 47% 38%, 65%, 61%, 77%, 75%, and 68%, respectively. Seaweed treatment improved these indices, with the 80% seaweed group showing increases of 27%, 21%, 44%, 36%, 56%, and 48%, 54% after 21 days. Additionally, seaweed application enhanced antioxidant activities in the roots (SOD by 71%, CAT by 45%, POD by 51%, and APX by 92%) and in the leaves (SOD by 18%, CAT by 26%, POD by 34%, APX by 58%) compared to the control. The study concluded that seaweeds significantly mitigated oxidative stress in plants, boosting growth, antioxidant potential, mineral absorption, and osmotic protection. Nigeria seaweeds could be a promising tool to enhance food production by reducing oxidative stress in crops.

Sensitive Hydraulic and Stomatal Decline in Extreme Drought Tolerant Species of California Ceanothus.

Identifying the physiological mechanisms by which plants are adapted to drought is critical to predict species responses to climate change. We measured the responses of leaf hydraulic and stomatal conductances (Kleaf and gs, respectively) to dehydration, and their association with anatomy, in seven species of California Ceanothus grown in a common garden, including some of the most drought-tolerant species in the semi-arid flora. We tested for matching of maximum hydraulic supply and demand and quantified the role of decline of Kleaf in driving stomatal closure. Across Ceanothus species, maximum Kleaf and gs were negatively correlated, and both Kleaf and gs showed steep declines with decreasing leaf water potential (i.e., a high sensitivity to dehydration). The leaf water potential at 50% decline in gs was linked with a low ratio of maximum hydraulic supply to demand (i.e., maximum Kleaf:gs). This sensitivity of gs, combined with low minimum epidermal conductance and water storage, could contribute to prolonged leaf survival under drought. The specialized anatomy of subg. Cerastes includes trichomous stomatal crypts and pronounced hypodermis, and was associated with higher water use efficiency and water storage. Combining our data with comparative literature of other California species, species of subg. Cerastes show traits associated with greater drought tolerance and reliance on leaf water storage relative to other California species. In addition to drought resistance mechanisms such as mechanical protection and resistance to embolism, drought avoidance mechanisms such as sensitive stomatal closure could contribute importantly to drought tolerance in dry-climate adapted species.

A chloroplast localized heavy metal-associated domain containing protein regulates grain calcium accumulation in rice

Calcium (Ca) is an essential mineral nutrient and plays a crucial signaling role in all living organisms. Increasing Ca content in staple foods such as rice is vital for improving Ca nutrition of humans. Here we map a quantitative trait locus that controls Ca concentration in rice grains and identify the causal gene as GCSC1 (Grain Ca and Sr Concentrations 1), which encodes a chloroplast vesicle localized homo-oligomeric protein. GCSC1 exhibits Ca2+ transport activity in heterologous assays in yeast and Xenopus laevis oocytes and is involved in the efflux of Ca2+ from the chloroplast to the cytosol. Knockout of GCSC1 results in increased chloroplast Ca concentration, lower stomatal conductance in leaves and enhanced Ca allocation to grains. Natural variation in grain Ca concentration is attributed to the variable expression of GCSC1 resulting from its promoter sequence variation. Our study identifies a chloroplast localized heavy metal-associated domain containing protein that regulates chloroplast Ca2+ efflux and provides a way to biofortify Ca in rice to benefit human nutrition.

Exogenous hydrogen sulfide increased Nicotiana tabacum L. resistance against drought by the improved photosynthesis and antioxidant system

Drought stress is an abiotic stressor that impacts photosynthesis, plant growth, and development, leading to decreased crop yields. Sodium hydrosulfide (NaHS), an exogenous additive, has demonstrated potential regulatory effects on plant responses to polyethylene glycol-induced drought stress in tobacco seedlings. Compared to the control, drought stress induced by 15 g/L PEG-6000 significantly reduced several parameters in tobacco seedlings: shoot dry weight (22.83%), net photosynthesis (37.55%), stomatal conductance (33.56%), maximum quantum yield of PSII (Fv/Fm) (11.31%), photochemical quantum yield of PSII (ΦPSII) (25.51%), and photochemical quenching (qP) (18.17%). However, applying NaHS, an H2S donor, mitigated these effects, ultimately enhancing photosynthetic performance in tobacco seedlings. Furthermore, optimal NaHS concentration (0.4 mM) effectively increased leaf stomatal aperture, relative water content (RWC) and root activity, as well as facilitated the absorption of N, K, Mg and S. It also enhanced the accumulation of soluble sugar and proline content to maintain osmotic pressure balance under drought stress. Compared to drought alone, pretreatment with NaHS also bolstered the antioxidant defense system in leaves, leading to 22.93% decrease in hydrogen peroxide (H2O2) content, a 22.19% decrease in malondialdehyde (MDA) content and increased activities of ascorbate peroxidase (APX) by 28.13%, superoxide dismutase (SOD) by 17.07%, peroxidase (POD) by 46.99%, and catalase (CAT) by 65.27%. Consequently, NaHS protected chloroplast structure and attenuated chlorophyll degradation, thus mitigating severe oxidative damage. Moreover, NaHS elevated endogenous H2S levels, influencing abscisic acid (ABA) synthesis and the expression of receptor-related genes, collaboratively participating in the response to drought stress. Overall, our findings provide valuable insights into exogenous NaHS’s role in enhancing tobacco drought tolerance. These results lay the foundation for further research utilizing H2S-based treatments to improve crop resilience to water deficit conditions.

Physiological Behavior of Rubber Plants (<i>Hevea Brasilliensis</i>) to Different Soil Moisture Conditions

Drought conditions can severely impact rubber (<i>Hevea brasiliensis</i>) plantations, leading to economic loss in Malaysia. The study aimed to assess the impact of varying soil moisture levels on the physiological characteristics of five latex timber clones (LTCs) of rubber, with the goal of identifying the most suitable clone for specific soil moisture conditions. These conditions include (1) field capacity, (2) 75% available water (AW), (3) 50% AW, (4) 25% AW, and (5) wilting point, with the ultimate objective of optimizing cultivation methods and fostering sustainable rubber production in Malaysia. The five clones under investigation include RRIM3001, RRIM2025, RRIM2001, RRIM928, and PB350. Leaf chlorophyll content, stomatal conductance, and net photosynthesis were measured 4 and 8 months after treatment (MAT). The findings indicated significant effects of moisture stress on various physiological attributes, including total chlorophyll content, relative chlorophyll content, stomatal conductance, and net photosynthesis rate. At 4 and 8 MATs, the clones subjected to field capacity exhibited the highest values for these physiological characteristics, followed by those exposed to 75% available water, with the lowest values observed at the wilting point. RRIM3001 consistently exhibited the highest total chlorophyll content, stomatal conductance, and net photosynthesis among the clones at both sampling dates. The highest net photosynthesis was observed in the RRIM3001 clone under field capacity conditions. Furthermore, a significant positive correlation was identified between total chlorophyll and relative chlorophyll contents, as well as between net photosynthesis and stomatal conductance. These findings carry practical implications for water management during the initial growth phase of rubber seedlings and for replanting initiatives in rubber plantations.

Investigating the potency of ethylenediurea (EDU) in alleviating the affliction of ambient ozone in heat labile tomato cultivars (Solanum lycopersicum L.).

Tomato is the second most valuable vegetable crop, and its susceptibility to tropospheric ozone (O3) varies on the cultivar. Eight tomato cultivars with documented O3 sensitivity were reevaluated using ethylenediurea (400ppm EDU) to determine the effectiveness of EDU in assessing O3 sensitivity under heavily O3-polluted tropical conditions. EDU helped in amending the growth, photosynthetic pigments, photosynthetic rate, stomatal conductance, and yield characteristics in the tomato cultivars. EDU reduced the lipid peroxidation and reactive oxygen species content, while enzymatic and non-enzymatic antioxidant responses differed across cultivars. The cultivar Superbug and Sel-7 (O3 susceptible) performed better by employing more biomass and yield and exhibiting more potent antioxidative defense machinery mainly non-enzymatic antioxidants after EDU treatment. The higher value of total antioxidative potential (TAP) in O3 susceptible cultivars suggested the adaptive resilience through EDU application against O3 stress. EDU application greatly enhanced the photosynthetic rate in O3 susceptible cultivars by increasing the stomatal conductance. Hence, both biophysical and biochemical responses were involved in protection against O3 provided by EDU. Kashi chayan and VRT02 (O3 tolerant) cultivars showed least response to EDU, due to their efficient inherent mechanisms in alleviating O3 stress. Thus, EDU may be used as an efficient biomonitoring tool against O3-sensitive cultivars.

Silicon Application Contributes to Efficient Gas Exchange in Tomato Plants

The study aimed to analyze the effect of silicon application on tomato crops subjected to different water management conditions. The experiment was conducted in a completely randomized design with two water replacement conditions (60 and 100% of crop evapotranspiration - ETc), four forms of silicon application (no application, full-dose soil application, split soil application and foliar application) with four replicates. When the plants were in the reproductive stage, gas exchange analysis was performed in two periods (critical period before water replacement and after water replacement). The photosynthesis rates, internal CO2, stomatal conductance, transpiration, and instantaneous water use efficiency were determined. The data were subjected to analysis of variance and the means compared by the Tukey test with 5% significance. The application of silicon caused significant variation in gas exchange in tomato leaves, with an increase in rates and an increase in instantaneous water use efficiency. The application of silicon promotes an increase in gas exchange in tomato plants, whether in adequate water conditions or with a deficit in the crop. The application of the element, via soil and foliar, showed a significant increase in gas exchange in tomato plants. The best results were obtained for application via soil, regardless of the water condition or time of evaluation.

Characterizing the hysteretic effects of water and salinity stresses on root-water-uptake

Characterizing the effects of previous water and salinity stresses is critical for the evaluation of plant water status, which, in turn, is essential for understanding soil-plant water relations and optimizing irrigation schemes. Recent research has found that hysteresis of plant response following water stress alone can be described by an exponential function of the stress degree on the previous day. To explore and quantify the effects of hysteresis concerning salinity stress and combined water-salinity stress, a hydroponic experiment and a soil column experiment on winter wheat, and a field experiment on cotton were conducted. Like water stress, previous salinity stress and combined water-salinity stress also resulted in hysteretic effects on root-water-uptake. Leaf stomatal conductance and plant transpiration rate of stressed crops could only recover gradually from a previous stressed status after re-watering. When stress was mild, compensatory recovery was found, while incomplete recovery occurred when stress was severe. Although the recovery process was closely related to stress history and type, a recovery coefficient was quantified universally with an exponential function of the stress extent on the previous day (with a coefficient of determination R2 ≥ 0.60). Consideration of hysteresis for water and salinity stresses with a mathematical model led to significant improvement in the simulation of both relative transpiration rate (R2 = 0.94, root mean squared error RMSE = 0.04, maximal absolute error MAE = 0.12) and soil water content (R2 = 0.90, RMSE = 0.01 cm3 cm–3, MAE = 0.03 cm3 cm–3), especially during the recovery periods severely affected by historical stress. Consideration of hysteresis is expected to benefit regulation of soil water and salinity and thus enhance water use efficiency. However, the mechanisms underlying hysteresis, especially the compensatory recovery mechanisms, still need to be further investigated.

Morphophysiological, biochemical, and nutrient response of spinach (Spinacia oleracea L.) by foliar CeO2 nanoparticles under elevated CO2

Nanomaterials offer considerable benefits in improving plant growth and nutritional status owing to their inherent stability, and efficiency in essential nutrient absorption and delivery. Cerium oxide nanoparticles (CeO2 NPs) at optimum concentration could significantly influence plant morpho-physiology and nutritional status. However, it remains unclear how elevated CO2 and CeO2 NPs interactively affect plant growth and quality. Accordingly, the ultimate goal was to reveal whether CeO2 NPs could alter the impact of elevated CO2 on the nutrient composition of spinach. For this purpose, spinach plant morpho-physiological, biochemical traits, and nutritional contents were evaluated. Spinach was exposed to different foliar concentrations of CeO2 NPs (0, 25, 50, 100 mg/L) in open-top chambers (400 and 600 CO2 μmol/mol). Results showed that elevated CO2 enhanced spinach growth by increasing photosynthetic pigments, as evidenced by a higher photosynthetic rate (Pn). However, the maximum growth and photosynthetic pigments were observed at the highest concentration of CeO2 NPs (100 mg/L) under elevated CO2. Elevated CO2 resulted in a decreased stomatal conductance (gs) and transpiration rate (Tr), whereas CeO2 NPs enhanced these parameters. No significant changes were observed in any of the measured biochemical parameters due to increased levels of CO2. However, an increase in antioxidant enzymes, particularly in catalase (CAT; 14.37%) and ascorbate peroxidase (APX; 10.66%) activities, was observed in high CeO2 NPs (100 mg/L) treatment under elevated CO2 levels. Regarding plant nutrient content, elevated CO2 significantly decreases spinach roots and leaves macro and micronutrients as compared to ambient CO2 levels. CeO2 NPs, in a dose-dependent manner, with the highest increase observed in 100 mg/L CeO2 NPs treatment and increased roots and shoots magnesium (211.62–215.49%), iron (256.68–322.77%), zinc (225.89–181.49%), copper (21.99–138.09%), potassium (121.46–138.89%), calcium (118.22–91.32%), manganese (133.15–195.02%) under elevated CO2. Overall, CeO2 NPs improved spinach growth and biomass and reverted the adverse effects of elevated CO2 on its nutritional quality. These findings indicated that CeO2 NPs could be used as an effective approach to increase vegetable growth and nutritional values to ensure food security under future climatic conditions.

Identification of drought-salinity combined stress in tomato plants by vegetation indices

A major issue in several farming areas of the Mediterranean basin consists of drought and salinity stress. This stress is mainly due to a steady exposition of warm daily temperature and heatwaves, moreover with inevitable irrigation with saline water. Therefore, detecting the stress is essential to minimise significant yield loss and preserve agricultural sustainability. In this context, remote and proximal sensing can play a crucial role in allowing fast, not destructive, extensive, and reliable assessment of crop status. In this work, the effectiveness of several multispectral indices in detecting salinity and water stress in tomato plants, grown under controlled green-house conditions, was investigated. Three different classifiers (fine tree model, linear discriminant model, and linear support vector machines model) were used to verify whether, and the extent to which, the adopted multispectral indices can be adopted to identify a stress condition of the tomato plants. In the experimental campaign, the stress occurrence on tomato plants was assessed on the base of a set of ecophysiological measurements, such as transpiration, stomatal conductance, and photosynthesis rate. Obtained results showed that a classification model based on linear support vector machines, exploiting the combination of Photochemical Reflectance Index and the Chlorophyl Index, can detect drought and salinity stress in tomato plants with an accuracy higher than 94%.

Application of additional dose of N could sustain rice yield and maintain plant nitrogen under elevated ozone (O3) and carbon dioxide (CO2) condition

IntroductionGlobal food security is challenged by the increasing levels of air pollutants like ozone (O3) through their impacts on crop productivity. The present study was conducted to quantify the interactive effect of elevated ozone (O3) and carbon dioxide (CO2), on different rice varieties in northern India.MethodsAn experiment was conducted in Genetic H field, Environment science, IARI for two consecutive years (2020 and 2021) during the kharif season, to quantify the impact of elevated O3 and CO2 interaction on productivity, and plant N in three rice varieties (Pusa basmati 1121, Nagina 22, IR64 Drt1) under different nitrogen (N) management practices. Rice crop was grown in Free Air Ozone-Carbon dioxide Enrichment rings (FAOCE) rings with two levels of O3 (elevated 60 ±10ppb and ambient) and two levels of CO2 (elevated, 550±25 ppm and ambient) concentration and their interaction with two N fertilizer treatments i.e., 100% RDN (recommended dose of N) and 125% RDN.Results and discussionElevated O3 significantly decreased physiological parameters like photosynthesis rate, stomatal conductance and transpiration rate of the crop. Grain yield reduced by 7.2-7.5%, in Pusa Basmati 1121 and from 6.9-9% in IR64 Drt1 varieties in elevated O3 treatment as compared to ambient treatment. Yield reduction in Nagina 22 variety was not significant in elevated O3 treatment. Elevated CO2 concentration of 550 ppm was able to fully compensate the yield loss in Nagina 22 variety and partially compensate (3.9-8.0%) in Pusa Basmati 1121 and IR64 Drt1 varieties. Grain N concentration in rice varieties decreased by 10.8-14.7% during first year and by 7.8-20.6% during second year in elevated O3 plus CO2 interaction treatment than ambient. Grain N uptake also decreased (13.2-17.1% in first year and 4.5-22.8% in second year) in elevated O3 plus CO2 interaction treatment as compared to ambient. Application of additional 25% of recommended dose of N improved grain N concentration, grain N uptake as well as available N of soil as compared to 100% RDN treatment in elevated O3 plus CO2 interaction treatment. Additional 25% N dose could help in sustaining rice productivity and quality under elevated O3 and CO2 condition.

Bacillus endophytic strains control Fusarium wilt caused by Fusarium oxysporum f. sp. lycopersici in tomato cv. Perinha.

Fusarium wilt is one of main phytopathology attacking tomato (Solanum lycopersicum L.) plantations in Brazil. Plant rhizosphere and endophytic beneficial microorganism are well known as plant growth promoters and biocontrol agents. The present study aims to evaluate the potential of different Bacillus strains as biocontrol agent to Fusarium oxysporum f. sp. lycopersici Race 3 strains; and also as plant growth promoting bacteria on Solanum lycopersicum cv Perinha. Different in vitro and greenhouse experiments were carried out to evaluate the direct and indirect bacterial-fungus antagonism, and they inoculation effects on plant traits. In vitro direct, metabolites, and volatile antagonism analysis demonstrated that B. toyonensis BR 10491(FORT 02) presented a broad antagonism to all tested race 3 FOL strains while B. megaterium BR 10466 (FORT 12), B. aryabhattai BR 10494 (FORT 25), B. stratosphericus BR 10438 (FORT 29) and B. cereus BR 10493 (FORT 113.1) strains showed significant antagonistic activity for at least two applied methods. Greenhouse pot experiments demonstrated a significant BCA effect of FORT 113.1 and FORT 02 against FOL Race 3 Fus 1302 strain during different tomato development stages (seedling, vegetative, and reproductive). Bacillus cereus (FORT 113.1) showed significantly higher shoot and height fresh weight, Chlorophyll a and Chlorophyll b content, stomata conductance, water use efficiency, and also a lower xylem infection percentage during vegetative and reproductive stages. Antioxidant enzymatic components analysis demonstrated a synergic effect of Fusarium and Bacillus inoculation, leading to a higher superoxide dismutase (SOD), catalase (CAT), and ascorbate peroxidase (APX) activity. In conclusion, the results suggest that strain FORT113.1 could be considered as a good candidate for production of new biofungicide with high potential to augment the existing biocontrol strategies.

Biological Acclimatization of Micropropagated Al-Taif Rose (Rosa damascena f. trigintipetala (Diek) R. Keller) Plants Using Arbuscular Mycorrhizal Fungi Rhizophagus fasciculatus

Tissue culture is used to multiply Al-Taif rose (Rosa damascena f. trigintipetala (Diek) R. Keller) plants in order to meet the demands of the fragrance, cosmetic, and floriculture industries. The use of arbuscular mycorrhizal fungus (AMF) could potentially improve plant growth and acclimatization performance to ex vitro conditions. Thus, in the current study, we investigated how AMF Rhizophagus fasciculatus influences the growth, establishment, and physiological performance of micropropagated Al-Taif rose plants during the acclimatization stage. The growth and physiological parameters of the AMF-treated plants were evaluated after a 12 week growth period in the growth chambers. The plants treated with AMF exhibited greater height (25.53 cm) and biomass growth values for both shoot fresh weight (0.93 g/plant) and dry weight (0.030 g/plant), more leaves (11.3/plant), more leaf area (66.15 cm2), longer main roots (15.05 cm/plant), total root length (172.16 cm/plant), total root area (64.36 cm2/plant), and biomass from both fresh weight (383 mg/plant) and dry weight (80.00 mg/plant) of the plants. The plants treated with AMF also exhibited increased rates of net CO2 assimilation, stomatal conductance, and transpiration compared to the control plants. The proline content in the leaves and roots was significantly lower in the AMF-treated plants than untreated plants. The Fv/Fm ratio, which serves as an indicator of the intrinsic or maximal efficacy of Photosystem II (PSII) demonstrated a notable decline in the untreated Al-Taif rose plants. These results elucidate the advantageous impact of AMF colonization on micropropagated Al-Taif rose plants, thereby enhancing their resilience against adverse ex vitro conditions.

Evaluation of Kabuli Chickpea Genotypes for Tropical Adaptation in Northern Australia

Chickpea is one of the economically important legume crops adapted for winter season production in tropical climates. This study evaluated the physiological, morphological, and biochemical traits of eight Kabuli chickpea genotypes in an Australian tropical environment. The result revealed significant differences between genotypes for seed emergence, plant height, primary shoots, leaf number, leaf area index, gas-exchange parameters, seed yield, carbon discrimination (Δ13C), and natural abundance for nitrogen fixation. Among the tested genotypes, AVTCPK#6 and AVTCPK#19 exhibited late flowering (60–66 days) and late maturity (105–107 days), and had higher leaf photosynthetic rate (Asat) (28.4–31.2 µmol m−2 s−1), lower stomatal conductance (gsw) (516–756 mmol m−2 s−1), were associated with reduced transpiration rate (T) (12.3–14.5 mmol m−2 s−1), offered greater intrinsic water-use efficiency (iWUE) (2.1–2.3 µmol m−2 s−1/mmol m−2 s−1), and contributed a higher seed yield (626–746 g/m2) compared to other genotypes. However, a larger seed test weight (>60 g/100 seed) was observed for AVTCPK#24, AVTCPK#8, and AVTCPK#3. Similarly, a high proportion (45%) of larger seeds (>10–11 mm) was recorded for AVTCPK#24. Furthermore, a higher %Ndfa in AVTCPK#6 (71%) followed by AVTCPK#19 (63%) indicated greater symbiotic nitrogen fixation in high-yielding genotypes. Positive correlation was observed between %Ndfa and seed protein, as well as between seed yield and plant height, primary shoots, leaf count, leaf area index, leaf photosynthesis, stomatal conductance, transpiration rate at pod filling stage, biomass, and harvest index. An inverse correlation between (Δ13C) and iWUE, particularly in AVTCPK#6 and AVTCPK#19, indicates greater heat and drought tolerance, required for high-yielding Kabuli chickpea production in northern Australia.

AtZAT10/STZ1 improves drought tolerance and increases fiber yield in cotton

Drought poses a significant challenge to global crop productivity, necessitating innovative approaches to bolster plant resilience. Leveraging transgenic technology to bolster drought tolerance in crops emerges as a promising strategy for addressing the demands of a rapidly growing global populace. AtZAT10/STZ1, a C2H2-type zinc finger protein transcription factor has shown to significantly improve Arabidopsis’ tolerance to various abiotic stresses. In this study, we reports that AtSTZ1 confers notable drought resistance in upland cotton (Gossypium hirsutum), amplifying cotton fiber yield under varying conditions, including irrigated and water-limited environments, in field trials. Notably, AtSTZ1-overexpressing transgenic cotton showcases enhanced drought resilience across critical growth stages, including seed germination, seedling establishment, and reproductive phases. Morphological analysis reveals an expanded root system characterized by an elongated taproot system, increased lateral roots, augmented root biomass, and enlarged cell dimensions from transgenic cotton plants. Additionally, higher contents of proline, chlorophyll, soluble sugars, and enhanced ROS-scavenging enzyme activities are observed in leaves of transgenic plants subjected to drought, underscoring improved physiological adaptations. Furthermore, transgenic lines exhibit heightened photosynthetic rate, increased water use efficiency, and larger stomatal and epidermal cell sizes, coupled with a decline in leaf stomatal conductance and density, as well as diminished transpiration rates compared to the wild type counterparts. Transcriptome profiling unveils 106 differentially expressed genes in transgenic cotton leaves post-drought treatment, including protein kinases, transcription factors, aquaporins, and heat shock proteins, indicative of an orchestrated stress response. Collectively, these findings underscore the capacity of AtSTZ1 to augment the expression of abiotic stress-related genes in cotton following drought conditions, thus presenting a compelling candidate for genetic manipulation aimed at enhancing crop resilience.