Root Size Research Articles

USING SALT-TOLERANT RHIZOBIA TO IMPROVE THE SOYBEAN (GLYCINE MAX) RESILIENCE TO SALINITY

Soybean (Glycine max [L.] Merr.) is an economically important oilseed crop with an annual increase in growing grain demand. Soybean is a moderately salt-tolerant crop; however, salt stress conditions can affect its growth and yield-related traits and, eventually, reduce productivity. In saline soils, one of the techniques to increase soybean productivity is to use rhizobia inoculation. Although, using industrial rhizobia-based biofertilizers is often ineffective due to their lack of adaptability to salinity. Injecting soybeans with salt-tolerant and growth-promoting rhizobia helps mitigate the effects of salt stress harmful to crop plants. The recent study sought to isolate local strains of salt-tolerant rhizobia, studying its ability to increase soybean tolerance to salt stress conditions. Twenty-four local salttolerant rhizobium isolates underwent isolation from root nodules of soybean grown on saline soils. Studying their basic morphological and biochemical characteristics and ability to withstand salt stress led to the final selection of five salt-tolerant strains. The rhizobium strains were able to synthesize metabolites that stimulate growth and help reduce salt stress in plants. The study of rhizobia nodulation ability under saline conditions resulted in selecting the three most efficient strains from the Bradyrhizobium japonicum species. Inoculation of soybean seeds with salt-tolerant rhizobia proved to mitigate the adverse effects of salinity on plant growth by increasing the root size and the number of nodules in the roots. Thus, the study establishes that inoculation of soybean seeds with local salttolerant rhizobia enhances soybean tolerance to salt stress and improves crop growth and adaptation to soil salinity. Using isolated local strains of salt-tolerant rhizobia will help provide a key and environmentally friendly approach to solving the problem of salt stress for sustainable agriculture.

Shift in fungal communities associated with Pinus sylvestris stands affected by root rot

Introduction
 Scots pine (Pinus sylvestris) covers large areas in European regions with significant economic importance to Ukrainian forest industry. Root rot caused by the wood-decay fungus Heterobasidion annosum damages both below- and above-ground parts of Scots pines. The disease progress is likely to be affected by reshaping in the forest such as soil properties, vegetation composition, and tree age. These changes are apparently followed up by paralleled shifts in fungal community composition on forest soil with potential feedback on ecosystem functioning.
 The objective of the study was to screen fungal groups associated with the root system of P. sylvestris in stands affected by H.annosum s.s. to better understand the pathogenesis and development of root rot infection, as well as to recognize whether root size and disease severity affect diversity of fungi of the root system in the forest-steppe conditions of Ukraine. The additional object was to study other resident microflora of P. sylvestris root infested by H.annosum s.s. to find out whether the H. annosum s.s. impacts the overall diversity of other fungi.
 Materials and Methods
 The field study was carried out in 2018–2020. Field study sites were pure pine forest stands located in Kharkiv region (compartment 126, subcompartment 7, tract Bugri, Kharkiv Forest Research Station). Wood core and root samples from P. sylvestris were collected from the five infected (50–100 m apart from each other) and five non-infected trees (up to 500 m apart from the infested area and 50–100 m apart from each other). Wood and root samples were used for fungal culturing and direct sequencing using ITS1F and ITS4 primers.
 Results
 In the present study, we tried to evaluate fungal communities across diseased Pinus sylvestris stands and investigated correlations between taxonomic composition and forest health. Not surprisingly, root rot infestation had a significant effect on root-associated fungal abundance and diversity. During disease development, the root-associated fungal community shifted in composition from dominance by saprotrophic fungi to ectomycorrhizal and pathogenic fungal species. Our results suggested that maintenance of functional diversity in the root-associated fungal community may sustain long-term forest health or even root rot resistance to some extent by retaining a capacity for symbiosis-driven recycling of organic nutrients; however, this hypothesis is necessary to carefully examine and prove further.
 Conclusions
 Fungal culturing from 10 surface-sterilized wood cores resulted in 21 fungal cultures, 2.1 per wood segment. Direct sequencing from 40 surface-sterilized segments of lateral roots resulted in 247 fungal sequences or 6.2 per root segment on average. The most dominant fungi from the infested trees of Pinus sylvestris were Dactylonectria macrodidyma (4.98%), Acremonium sp (4.52%), Cladosporium cladosporioides (4.07%) from Ascomycota and Heterobasidion annosum s.s. (4.07%) from Basidiomycota, while for non-infested group Unidentified Ascomycota175244 (13.19%), Penicillium spinulosum (9.89%), Acremonium sp. (8.79%), Bionectriaceae sp. (8.79%) were the most common.
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The sensitivity of radish cultivars to high temperatures during germination and seedling growth stages

A laboratory experiment was conducted at constant temperatures of 20, 23, 26, 29, 32, 35, 38, and 41℃ to identify the response of six radish cultivars with different root sizes and colors to high-temperature stress during germination, emergence, and early seedling growth stage. Also, the optimal temperature was determined by calculating the relationship between seedling length and temperature via a polynomial regression model. The results showed that no seed germination was detected at 41℃, while emergence and seedling growth were not observed at 38℃ and above. Similar germination percentages, mean germination time, and germination index were obtained between 20℃ and 35℃. The root length reduced at 32℃ and it was more sensitive to high temperatures than shoots because the root/shoot length ratio showed a decreasing trend by increasing temperatures and longer root length was recorded at lower temperatures than 32℃. There were genotypic variations among radish cultivars for temperatures and ‘Kırmızı İnci’, ‘Beyaz İnci’, and ‘Siyah İnci’ produced a better performance than the others under high temperatures. The regression analysis predicted the optimal temperatures as 21.5℃ and 22.6℃ for root and shoot length, respectively. This study indicates that high temperatures inhibited seedling growth rather than seed germination performance of radishes.

The effect of experimental warming on fine root functional traits of woody plants: Data synthesis

Fine root traits are critical to plant nutrition and water uptake, and soil nutrient cycling. The impacts of climate warming on woody plants are predicted to be severe, but the effects on the fine root traits of woody plants remain unclear. To evaluate the effects of warming on fine-root traits of woody plants, we synthesized 431 paired observations of 13 traits from 78 studies. The result showed that warming increased the fine root nitrogen (N) concentration, root mortality, and root respiration, but decreased fine root phosphorus (P) concentration, root C:N and root nonstructural carbohydrates (NSC) concentration. However, warming had no significant effect on fine root biomass, root production and morphological traits. Warming effects on fine root biomass and root diameter decreased with warming magnitude, while root P concentration increased. Moreover, with increasing warming duration, the effect size of specific root length (SRL), root length, root C:N and root NSC increased. The effects size of root biomass, root diameter, root length and root C:N decreased with mean annual temperature (MAT) and mean annual precipitation (MAP) increase. However, the effect size of root N concentration increased with higher MAT and MAP. Furthermore, warming increased the fine root biomass of ectomycorrhiza (ECM) plants, but decreased that of plants associated with arbuscular mycorrhizal (AM) fungi. These results indicate that the effect of warming on fine root traits of woody plants was not only modulated by warming duration and magnitude, but also MAT and MAP. Our findings highlight the differential warming responses to fine root traits of woody plants, which have strong implications for shrubs and tree-dominated ecosystems soil nutrients cycling and carbon stocks.

Longitudinal Aortic Root Dilatation in Collegiate American-Style Football Athletes.

Background Clinically relevant aortic dilatation (>40 mm) and increased cardiovascular risk are common among retired professional American-style football athletes. Among younger athletes, the effect of American-style football participation on aortic size is incompletely understood. We sought to determine changes in aortic root (AR) size and associated cardiovascular phenotypes across the collegiate career. Methods and Results This was a multicenter, longitudinal repeated-measures observational cohort study of athletes across 3 years of elite collegiate American-style football participation. A total of 247 athletes (119 [48%] Black, 126 [51%] White, 2 [1%] Latino; 91 [37%] linemen, 156 [63%] non-linemen) were enrolled as freshmen and studied at pre- and postseason year 1, postseason year2 (N=140 athletes), and postseason year 3 (N=82 athletes). AR size was measured with transthoracic echocardiography. AR diameter increased over the study period from 31.7 (95% CI, 31.4-32.0) to 33.5 mm (95% CI, 33.1-33.8; P<0.001). No athlete developed an AR ≥40 mm. Athletes also demonstrated increased weight (cumulative mean Δ, 5.0 [95% CI, 4.1-6.0] kg, P<0.001), systolic blood pressure (cumulative mean Δ, 10.6 [95% CI, 8.0-13.2] mm Hg, P<0.001), pulse wave velocity (cumulative mean Δ, 0.43 [95% CI, 0.31-0.56] m/s, P<0.001), and left ventricular mass index (cumulative mean Δ, 21.2 [95% CI, 19.2-23.3] g/m2, P<0.001), and decreased E' velocity (cumulative mean Δ, -2.4 [95%CI, -2.9 to -1.9] cm/s, P<0.001). Adjusting for height, player position, systolic blood pressure, and diastolic blood pressure, higher weight (β=0.030, P=0.003), pulse wave velocity (β=0.215, P=0.02), and left ventricular mass index (β=0.032, P<0.001) and lower E' (β=-0.082, P=0.001) were associated with increased AR diameter. Conclusions Over the collegiate American-style footballcareer, athletes demonstrate progressive AR dilatation associated with cardiac and vascular functional impairment. Future studies delineating aortic outcomes are necessary to determine whether AR dilation is indicative of maladaptive vascular remodeling in this population.

The root of the problem: diverse vulnerability to xylem cavitation found within the root system of wheat plants.

The propagation of xylem embolism throughout the root systems of drought-affected plants remains largely unknown, despite this process being comparatively well characterized in aboveground tissues. We used optical and X-ray imaging to capture xylem embolism propagation across the intact root systems of bread wheat (Triticum aestivum L. 'Krichauff') plants subjected to drying. Patterns in vulnerability to xylem cavitation were examined to investigate whether vulnerability may vary based on root size and placement across the entire root system. Individual plants exhibited similar mean whole root system vulnerabilities to xylem cavitation but showed enormous 6 MPa variation within their component roots (c. 50 roots per plant). Xylem cavitation typically initiated in the smallest, peripheral parts of the root system and moved inwards and upwards towards the root collar last, although this trend was highly variable. This pattern of xylem embolism spread likely results in the sacrifice of replaceable small roots while preserving function in larger, more costly central roots. A distinct pattern of embolism-spread belowground has implications for how we understand the impact of drought in the root system as a critical interface between plant and soil.

English

Sweetpotato is an important food, feed and vegetable crop in Niger and Nigeria. The adoption of a new variety depends on famers and consumers preferences. The objective of this study was to identify sweetpotato preferred traits by end-users in Niger and Nigeria. The study was conducted in two countries through participatory rural appraisal. The results revealed that sweetpotato is produced by men in Niger, while it is mostly produced by women in South-East Nigeria. In Niger, 100% of cultivated varieties were landraces, while 75.00% in Nigeria were landraces. Results showed that in Niger, farmers preferred high yielding, white flesh colour, and drought tolerant varieties, while in Nigeria they preferred high yielding, white flesh colour, and earliness cultivars. Traders and consumers in both countries preferred healthy, white flesh colour and big storage root size varieties. There is a need of effective breeding program in Niger, and both countries should turn toward developing cultivars with high yield, drought tolerant, and pest and disease resistant. Key words: sweetpotato, preferred trait, farmer, consumer, Niger, Nigeria.

Perceived Knowledge of Cassava Value Chain Actors on Varietal Preferences for Various End Uses

This study assessed end users’ perceptions about preferred traits for various end uses, constraints, and varietal preferences using Participatory Rural Appraisal (PRA). A purposive sampling procedure was used to identify value chain actors. A total of 360 questionnaires were administered to 120 producers, 72 processors, 72 consumers and 96 traders. The study revealed that, 89.2% of the respondents grow cassava only whilst 82.5% grow and process in the three study districts. Farmers commonly select cassava varieties with focus on high yield, root size, root taste, early maturity period and inner color. Mean rank of studied traits were significantly (p ≤ 0.0001) differed among cassava producers and processors. In Bo district, high root yield (1st), root size (2nd), dry matter content (3rd) and starch content (4th), were the most important traits. In Bombali district, high root yield (1st), root taste (2st), dry matter content (3rd) and poundability (4th) were the most desired. In Kenema district, high root yield (1st), root taste (2st), maturity period (3rd), and poundability (4th), were the most desired. The overall ranking based on producers’ selection criteria revealed that starch content, dry matter content, root size and ease of peeling as the top key traits considered for cassava processing. Results suggest that participatory variety selection and participatory plant breeding techniques should be explored to promote collaborations between stakeholders and breeders for development of new cassava varieties with desired traits including high dry matter content, high root yield, high starch content and other desired key quality traits.

Impact of physician performed point of care ultrasound (POCUS) during first outpatient cardiology consultation on patient management and downstream testing.

Goal directed point of care ultrasound (POCUS) is a bedside tool to assist with clinical diagnosis. We examined the impact of POCUS performed by consulting cardiologist (CC) during initial cardiology consult on clinical management and downstream testing. Sixty-nine study patients (pts) seen in a general cardiology outpatient clinic of a tertiary center by an expert imaging CC were compared to a control group of 65 pts seen by three different CCs without POCUS during the same time-period, in whom the first standard echo (SE) was performed after the initial visit. Baseline characteristics were similar between the two groups for age, cardiac risk factors, and referral diagnoses. Echo findings on POCUS and by SE (mean delay of 17.2days after visit) in the control group were comparable for RV size and function and for valvular heart disease. More patients with lower LVEF, higher LV filling pressures, new regional wall motion abnormalities, and increased aortic root size were present among POCUS group resulting in greater yield of echo abnormalities. There were more cardiovascular medication changes at the first visit (15.3% vs. 5.7%, p<.01), less referral for noninvasive stress testing (10% vs. 29%, p<.01), more advanced cardiac testing and subspecialty referrals (29% vs. 18% pts, p=.06), in the study compared to the control group after cardiology visit. POCUS at time of consultation detects more abnormal echo findings, results in more medication adjustments, less referral for noninvasive stress testing, earlier referral for advanced cardiac diagnostic imaging, and subspecialty cardiac referrals.

17 Beta-estradiol impedes aortic root dilation and rupture in male Marfan mice

Background: Marfan syndrome causes a hereditary form of TAA with dilation of the aortic root. Male patients with Marfan syndrome are more likely than women to have aortic dilation and dissection and mouse models of Marfan syndrome demonstrate larger aortic roots in males compared to females even after adjustment for body size. In this study we examine the effects of estrogen17 β-estradiol on aortic dilation and rupture in a Marfan mouse model. Methods: Marfan male mice were administered estrogen17 β-estradiol pellets with 60 day release and the growth in aortic root size was measured every 2 weeks for 8 weeks. Aortic root tissue from vehicle and 17 b-estradiol mice were subjected to proteomic analysis and bioinformatics was used to ascertain enriched pathways. Marfan mice with and without 17 b-estradiol were also treated with continuous angiotensin II infusion and survival was determined for 30 days. Results: Male Marfan mice with estrogen17 β-estradiol had a significant reduction in the ratio of aortic diameter 8 weeks after pellet implantation to baseline aortic diameter compared to the same ratio in Marfan mice with sham surgery. Proteomic analysis demonstrated complement C3 and C4 protein upregulation in Marfan mice compared to wild type and Marfan mice treated with 17 b-estradiol. Aortic smooth muscle cells express complement components in vivo and in vitro and expression of these factors are regulated by cytokines and estrogen17 β-estradiol in vitro. Additionally, 17 b-estradiol and female sex protect against aortic rupture when Marfan mice are treated with continuous infusion of angiotensin II and this protection correlates with lower protein levels of C3. Conclusions: Our findings support a protective role of 17 b-estradiol in preventing the dilation and rupture of aortic roots in Marfan male mice and suggest that these therapeutic actions may develop through anti-inflammatory properties. FAER Foundation for Anesthesia Education and Research This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Physiological and anatomical response of rice (Oryza sativa L.) ‘Hom Mali Daeng’ at different salinity stress levels

Abstract Soil salinity is a severe global stressor causing adverse impacts on irrigated land and drastically reducing crop yields, especially in rice, an important economic crop of Thailand. In this study, the impacts of salt stress on the anatomical and physiological features of 28-day-old rice (Oryza sativa L.) ‘Hom Mali Daeng’ were determined. Various NaCl concentrations (0, 50, 100, 150, and 200 mM) were applied every 2 days, with watering for 2 weeks. The results revealed that salinity stress inhibited the growth of rice. Leaf number, root size, fresh weight, and dry weight were significantly reduced. The electrolyte leakage percentage and malondialdehyde (MDA) content increased after treatment with high NaCl concentrations, while the SPAD unit and chlorophyll content were not significantly different between the control and NaCl treatments. Leaf anatomy changes were studied using freehand section and peeling techniques after salinity stress treatment. Lamina thickness in all treatments decreased, while cell wall and cuticle thickness increased. Stomatal density in all treatments significantly increased. Major vascular bundle, vessel, and phloem area of the 100 mM NaCl treatment were different when compared with the control and other treatments. The results provide information about the physiological and anatomical adaptation of ‘Hom Mali Daeng’ rice, which will be useful for further research in this and other rice cultivars.

Phosphorus deficiency tolerance in sorghum

Sorghum is a globally important commodity for food, feed, and fuel, and is known to have a high tolerance to heat, drought, and other abiotic stresses, and have a large genetic variation for grain yield under low-P conditions. Agricultural land in Indonesia is dominated by acid soils with limited P availability, of a total of 144.5 million ha, around 107.3 million ha are acid soils. Information regarding the tolerance of sorghum to P deficiency conditions is still very limited. The review aimed to discuss the adaptation strategy of sorghum to P deficiency. Studies showed that sorghum has a moderate adaptation to Al3+ stress with low P. Under various P levels, the performance of sorghum was also very diverse following the wide genetic diversity. From evaluations of several varieties and inbred lines with high tolerance to P deficiency that has been obtained, sorghum tolerance strategies to low P conditions are: (1) increase root size (length, diameter, and volume), and root proteoid on several genotypes, (2) increase secretion of oxalic acid, particularly in tolerant genotypes, the secretion of which are higher when Al3+ is present, (3) higher P-use efficiency (PUE), eventhough the specific absorption ratio (SAR) was lower than the sensitive ones. The high PUE is thought to contribute to higher grain weight compared to sensitive genotypes under P starvation condition, and (4) higher stay green percentage, which has a high correlation to grain weight/plant. Such strategies should be considered in precission breeding program of sorghum to P deficiency.&#x0D; Keywords: adaptation strategy; oxalic acid; P-use efficiency; sorghum genotypes; sorghum low P; stay green

Fosforo disponible de tres fuentes en el suelo y su efecto sobre la biomasa y desarrollo radical del maíz

Phosphorus deficiency in the country is very common, to overcome the problem high soluble phosphates are applied, the use a less soluble acidulated phosphate rock with sulfuric acid (RFA) is one economical alternative. The partial substitution of sulfuric acid by ammonium thiosulfate in the acidulation process (R30T) has proven feasible. The objective of this study was to prove the effect of these P sources on the maize behavior. Two soils were used a neutral and acidic one. Four doses of P treatments were used: 0, 70, 140 and 210 mg.kg-1, in a glasshouse experiment. 35 days after planting plants were harvest and soil and root samples were taken for phosphorus analysis and determination of dry matter, root length (LR) and root volume (VR). Partial substitution of sulfuric acid by ammonium thiosulfate does not affect the quality of the acidulated rock. A close relationship between biomass and P concentration in the corn tops with residual soil P, LR and VR increased with the first increase of soil P, successive increments of P produced a decrease in roots size. The LR and VR relationship with P uptake and biomass was not the same in the two soils, in the acidic soil there was a higher dependence on P uptake than in the neutral soil.

Natural variation of maize root hydraulic architecture underlies highly diverse water uptake capacities.

Plant water uptake is determined by the root system architecture and its hydraulic capacity, which together define the root hydraulic architecture. The current research aims at understanding the water uptake capacities of maize (Zea mays), a model organism and major crop. We explored the genetic variations within a collection of 224 maize inbred Dent lines and successively defined core genotype subsets to access multiple architectural, anatomical, and hydraulic parameters in the primary root (PR) and seminal roots (SR) of hydroponically grown seedlings. We found 9-, 3.5-, and 12.4-fold genotypic differences for root hydraulics (Lpr), PR size, and lateral root size, respectively, that shaped wide and independent variations of root structure and function. Within genotypes, PR and SR showed similarities in hydraulics and, to a lesser extent, in anatomy. They had comparable aquaporin activity profiles that, however, could not be explained by aquaporin expression levels. Genotypic variations in the size and number of late meta xylem vessels were positively correlated with Lpr. Inverse modeling further revealed dramatic genotypic differences in the xylem conductance profile. Thus, tremendous natural variation of maize root hydraulic architecture underlies a high diversity of water uptake strategies and paves the way to quantitative genetic dissection of its elementary traits.

Effect of Bio-Fertilizer and Banana Peel Extract on the Vegetative Traits and Yield of Carrot Plants

The field experiment was conducted in the training extension farm in Al-Mahanawiya / Al-Musayyab district, 25 km northwest of Hilla city center / Babylon province. The seeds of the stinger carrot hybrid were planted during autumn season on October 3, 2021. To study the effect of adding biofertilizers and banana peel extract on the vegetative growth and yield of carrots. The experiment was designed according to a split plot-system using a randomized complete block design with three replications. The results of the experiment were statistically analyzed according to the method of analysis of variance and according to the significant differences between the treatments at the probability level of 0.05 using the least significant difference LSD. The results indicated that bio-fertilization had a significant effect on (percentage of dry matter in the vegetative total) and (Fulzyme) scored a significantly excelled in (number of leaves, relative content of chlorophyll, percentage of dry matter in the root, root length, root diameter, average root weight and total yield). Treatment with the organic extract of banana peels showed at the concentration of 40 ml. L-1significantly excelled in (plant height, number of leaves, percentage of dry matter in vegetative and percentage of dry matter in the root) and at a concentration of 20 ml. L-1 in (relative content of chlorophyll in leaves, root size, average weight of the root and total yield). The bi-interaction of the biofertilization treatment and the organic extract indicated significant differences, where the interaction of Fulzyme and concentration 40 ml.L-1 was significantly excelled in the percentage of dry matter in the vegetative and root (29.67% and 13.09%), respectively. As for the Biohealth interaction and the concentration of 40 ml.L-1, it significantly excelled in the plant height (25.26 cm). The interaction Fulzyme and concentration 20 ml.L-1 recorded the highest root volume and average root weight (135.8 cm3, 80.9 g), respectively, The interaction between Biohealth and concentration of 20 ml.L-1 recorded the highest total yield (12.73 tons. ha-1) while it was the lowest for all studied traits when the control treatment of both biofertilization and banana peel extract.

Boosting neuregulin 1 type-III expression hastens SMA motor axon maturation

Intercellular communication between axons and Schwann cells is critical for attaining the complex morphological steps necessary for axon maturation. In the early onset motor neuron disease spinal muscular atrophy (SMA), many motor axons are not ensheathed by Schwann cells nor grow sufficiently in radial diameter to become myelinated. These developmentally arrested motor axons are dysfunctional and vulnerable to rapid degeneration, limiting efficacy of current SMA therapeutics. We hypothesized that accelerating SMA motor axon maturation would improve their function and reduce disease features. A principle regulator of peripheral axon development is neuregulin 1 type III (NRG1-III). Expressed on axon surfaces, it interacts with Schwann cell receptors to mediate axon ensheathment and myelination. We examined NRG1 mRNA and protein expression levels in human and mouse SMA tissues and observed reduced expression in SMA spinal cord and in ventral, but not dorsal root axons. To determine the impact of neuronal NRG1-III overexpression on SMA motor axon development, we bred NRG1-III overexpressing mice to SMA∆7 mice. Neonatally, elevated NRG1-III expression increased SMA ventral root size as well as axon segregation, diameter, and myelination resulting in improved motor axon conduction velocities. NRG1-III was not able to prevent distal axonal degeneration nor improve axon electrophysiology, motor behavior, or survival of older mice. Together these findings demonstrate that early SMA motor axon developmental impairments can be ameliorated by a molecular strategy independent of SMN replacement providing hope for future SMA combinatorial therapeutic approaches.

Comparison of the Allelopathic Potential of Non-Native and Native Species of Mediterranean Ecosystems.

Allelopathy is a frequent interaction between species in Mediterranean ecosystems and it is also one of the proposed strategies to explain the colonisation of invasive species. To confirm the importance of allelopathic potential as a mechanism of invasion of non-native species in Mediterranean ecosystems, it would be advisable to compare the allelopathic effects of non-native plants with native plants on the same target species and thus avoid overestimating the role of phytotoxicity in the invasion process. The main objective of this work was to compare the allelopathic activity of native species typical of Mediterranean ecosystems, classified as allelopathic, with the allelopathic activity of non-native species that may have an invasive character in these ecosystems. To this end, we selected three native species (Cistus ladanifer, Pistacia lentiscus, and Pistacia terebithus) and three non-native species (Acacia dealbata, Acer negundo, and Salix babylonica), and we analysed their effect on the species Lactuca sativa and the native species Lavandula stoechas and Echium plantagineum. The tests on L. sativa showed that all species have allelopathic activity. The tests on L. stoechas and E. plantagineum revealed that P. terebinthus exerted the greatest effect, being the only species that maintained an inhibitory effect at extract concentrations of 50% and 25% in all the analysed parameters, except in germination and cotyledon emergence for E. plantagineum. There were no significant differences in the effect on germination between non-native and native species, although significant differences were found in the effect on root size in the three analysed concentrations, with the native species producing greater inhibition. In conclusion, these species exert a negative effect on the selected native target species, but the negative effect of the native species is greater than that of the non-native species. These results indicate that it is important to compare the allelopathic effects of invasive and native species to correctly estimate the phytotoxic effect of invasive species on their invasiveness.

Role of biostimulants (ascorbic acid and fulvic acid) to synergize Rhizobium activity in pea (Pisum sativum L. var. Meteor)

Biostimulants such as ascorbic acid (AA) and fulvic acid (FA)can enhance the efficiency of root-nodulating bacteria. This study investigates optimum concentration of these two biostimulants to maximize the Rhizobium activity and increase root size, nodulation capability, NPK uptake, yield and quality. Interaction with nitrogenase enzyme through molecular docking was also studied by using both AA and FA as ligands to better understand their inhibitory role in excess amounts. The findings of the study suggest: the combined application of both FA and AA at 200 ppm concentrations proved to be more effective than the individual application. Excellent vegetative growth was noticed which translated into an increased reproductive growth i.e statistically significant increase in number of pods per plant, fresh and dry weight of pods per plant, number of seeds per pod, total chlorophyll, carotenoids and chemical constituents of pea seeds i.e. N (16.17%), P (40.47%), K (39.96%) and protein (16.25%). These findings were substantiated by molecular docking of nitrogenase enzyme with ascorbic acid and fulvic acid. The XP docking score of ascorbic acid (−7.07 kcal mol-1) and fulvic acid (−6.908 kcal mol-1) exhibited that the optimum doses (200 ppm) should be used as higher dose or their excess amount can hinder the Rhizobium activity of nitrogen fixation by interacting with the nitrogenase enzyme.

The ROP2 GTPase Participates in Nitric Oxide (NO)-Induced Root Shortening in Arabidopsis.

Nitric oxide (NO) is a versatile signal molecule that mediates environmental and hormonal signals orchestrating plant development. NO may act via reversible S-nitrosation of proteins during which an NO moiety is added to a cysteine thiol to form an S-nitrosothiol. In plants, several proteins implicated in hormonal signaling have been reported to undergo S-nitrosation. Here, we report that the Arabidopsis ROP2 GTPase is a further potential target of NO-mediated regulation. The ROP2 GTPase was found to be required for the root shortening effect of NO. NO inhibits primary root growth by altering the abundance and distribution of the PIN1 auxin efflux carrier protein and lowering the accumulation of auxin in the root meristem. In rop2-1 insertion mutants, however, wild-type-like root size of the NO-treated roots were maintained in agreement with wild-type-like PIN1 abundance in the meristem. The ROP2 GTPase was shown to be S-nitrosated in vitro, suggesting that NO might directly regulate the GTPase. The potential mechanisms of NO-mediated ROP2 GTPase regulation and ROP2-mediated NO signaling in the primary root meristem are discussed.

Crescimento de porta-enxerto de maracujazeiro silvestre (Passiflora foetida L.) sob salinidades da água de irrigação

ABSTRACT Wild passion fruit species, due to the greater tolerance to environmental stresses, reveal potential as interspecific rootstocks. Passiflora foetida is a wild species potentially tolerant to salinity. Therefore, the objective with the study was to evaluate the effects of irrigation water salinity on the growth of wild passion fruit (P. foetida L.) rootstocks. The experiment was carried out in a protected environment. The treatments consisted of the electrical conductivity of the irrigation water (0.3; 1.0; 2.0; 3.0 and 4.0 dS m-1), distributed in randomized blocks. The assessments were performed at 7, 14, 21, 28 and 35 days after transplanting and consisted of: stem height and diameter, number of leaves, average leaf size, leaf area, and dry matter of shoots, roots and total. In younger rootstocks, the deleterious effects of salinity on height growth and leaf components were observed under lower electrical conductivities, with tolerance increasing with age. However, dry biomass accumulation was more severely restricted by salinity with increasing rootstock age. P. foetida rootstocks are salinity tolerant and can be irrigated with water of up to 4.0 dS m-1.