Iron (Fe) deficiency is one of the major environmental stresses affecting plant production in the world. The selection of tolerant genotypes is considered an effective remediation strategy for this stress. The present study was carried out in order to investigate the biodiversity within Medicago truncatula plants in response to Fe deficiency, to identify tolerant genotypes and to assess the main tolerance mechanisms. To do this, a screening test was performed on 20 M. truncatula genotypes cultivated in minimal medium. Biometric and physiological markers were analyzed, including plant biomass, chlorophyll and root architecture. Results showed a biodiversity among the 20 genotypes. Interestingly, Fe deficiency tolerance was highest in TN8.20 and A17 genotypes. However, the lowest tolerance behavior was observed in TN1.11 and TN6.18. In order to investigate the main tolerance mechanisms, an experiment was conducted in the hydroponic system on already selected genotypes. Assessment of Fe deficiency tolerance was performed mainly on plant growth parameters, Fe (III)‐chelate‐reductase activity, rhizosphere acidification and antioxidant system defense. The relative better tolerance of A17 and TN8.20 to Fe deficiency was positively correlated with their capacity to maintain higher Fe‐acquisition efficiency in roots via rhizosphere acidification and the stimulation of Fe (III)‐chelate‐reductase activity. Moreover, tolerant genotypes showed the lowest decreases in chlorophyll content and photosynthetic activity (CO2 assimilation) compared to the sensitive ones. The efficiency of antioxidant capacity of the tolerant genotypes was revealed in stimulation of catalase (CAT) and peroxidase (POX) activities as well as accumulation of polyphenols, leading to the maintenance of cell integrity under Fe deficiency.

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Iron (Fe) deficiency leads to an overproduction of reactive oxygen species (ROS) in plants that activate their antioxidant systems to control oxidative burst. In this study, contrasting Medicago truncatula genotypes, A17 and TN8.20 (tolerant) and TN1.11 (sensitive), were grown under Fe deficiency. The superoxide dismutase (SOD: EC1.15.1.1) activity, their isoforms’ coding genes, the copper chaperone expression patterns, and leaf phenolic contents were analysed. Our results showed that Fe deficiency decreases the photosynthetic capacity and plant biomass production with a prominent effect on TN1.11 genotype. The tolerance of A17 and TN8.20 was correlated with a maintenance of Fe content and the photosynthetic apparatus and an increase of Cu concentration compared with the sensitive genotype. We revealed a significant increase of H2O2 in Fe-deficient plants, mainly in TN1.11 sensitive genotype. TN8.20 and A17 tolerance were concomitant with a significant increase of SOD activities (SOD, Cu/Zn-SOD, and Mn-SOD) under Fe deficiency. This increment was correlated to an induction of the copper chaperone gene expression level, as well as an accumulation of isoquercitin phenolic compound. Our study provides new insights into the orchestration of SOD’s isoforms activities, the expression of the copper chaperone, FeSOD, Cu/ZnSOD genes, and the leaf phenolic compounds accumulation that allows Medicago truncatula to overcome Fe deficiency.

There are rapid changes in worldwide species distribution and abundance especially in the tropics and subtropics where they occur in abundance relative to other regions of the world .Countries worldwide including Nigeria show strong inclination towards effective biodiversity monitoring to maintain and sustainably utilize their biological resources Nigeria is blessed with a plethora of biodiversity and biological resources including plants, animals and ecosystems to the extent that some of them are threatened to extinction and degradation resulting from the imbalance between economic development and biodiversity conservation. Some major threats to biodiversity conservation in Nigeria include poverty, economic development, incomplete or non implementation and non ratification by government of international treaties and conventions on conservation issues, ambiguous governmental laws on biodiversity, climate change, pollution, invasion by alien species etc. According to the IUCN Red list of 2013, Nigeria has a total of 309 threatened species in the following taxonomic categories: Mammals (26), Birds (19), Reptiles (8), Amphibians (13), Fishes (60), Mollusks (1), other Invertebrates (14) and Plants (168) Possible remedies include concerted effort towards the implementation and ratification of treaties and conventions on biodiversity, educating the populace to forgo cultural practices that are inimical to conservation of biological resources. The essence of this paper is to highlight some of these unwholesome practices that endanger biodiversity and to sensitize the populace on the importance of biodiversity conservation practices in Nigeria.

The aim of this study was to assess the effect of symbiotic bacteria inoculation on the response of Medicago truncatula genotypes to iron deficiency. The present work was conducted on three Medicago truncatula genotypes: A17, TN8.20, and TN1.11. Three treatments were performed: control (C), direct Fe deficiency (DD), and induced Fe deficiency by bicarbonate (ID). Plants were nitrogen-fertilized (T) or inoculated with two bacterial strains: Sinorhizobium meliloti TII7 and Sinorhizobium medicae SII4. Biometric, physiological, and biochemical parameters were analyzed. Iron deficiency had a significant lowering effect on plant biomass and chlorophyll content in all Medicago truncatula genotypes. TN1.11 showed the highest lipid peroxidation and leakage of electrolyte under iron deficiency conditions, which suggest that TN1.11 was more affected than A17 and TN8.20 by Fe starvation. Iron deficiency affected symbiotic performance indices of all Medicago truncatula genotypes inoculated with both Sinorhizobium strains, mainly nodules number and biomass as well as nitrogen-fixing capacity. Nevertheless, inoculation with Sinorhizobium strains mitigates the negative effect of Fe deficiency on plant growth and oxidative stress compared to nitrogen-fertilized plants. The highest auxin producing strain, TII7, preserves relatively high growth and root biomass and length when inoculated to TN8.20 and A17. On the other hand, both TII7 and SII4 strains improve the performance of sensitive genotype TN1.11 through reduction of the negative effect of iron deficiency on chlorophyll and plant Fe content. The bacterial inoculation improved Fe-deficient plant response to oxidative stress via the induction of the activities of antioxidant enzymes.

The first experiment was conducted to evaluate the impact of seed priming on germination behavior and seedling establishment in Vicia faba and Vicia sativa, for that, seeds priming was done using SA (100 µM) and KH2PO4. In order to determine the optimal concentration of KH2PO4 for improving germination, different concentrations were used: 25 µM, 50 µM, and 100 µM. The best germination behavior and seedling establishment were obtained with 25 and 50 µM KH2PO4, respectively for Vicia faba and Vicia sativa. Moreover, data showed that 100 µM of SA improved seed germination as well as the seedling establishment for both species. The second experiment was carried out to investigate the influence of seed priming for improving phosphorous (P) deficiency tolerance. To do, seedling obtained from primed and nonprimed seeds were grown in a hydroponic culture system with three different treatments: control (C, medium containing sufficient P concentration: 360 µM KH2PO4), direct phosphorus-deficient (DD, medium containing only 10 µM KH2PO4), and induced P deficiency by bicarbonate (ID, medium containing sufficient P concentration: 360 µM KH2PO4 + 0.5 g L-1 CaCO3 + 10 mM NaHCO3). Furthermore, the role of exogenous SA applied to P deficiency tolerance enhancement was explored. Seed priming or the exogenous application of SA significantly reduced the severity effect of P deficiency. In fact, the pretreated plants were observed more tolerant to P deficiency as reflected from the significant increase in plant biomass, P uptake, and an efficient antioxidant system. Overall, this paper highlights the beneficial effect of seeds priming or the exogenous application of SA in the improvement of plant tolerance to phosphorus deficiency.

Nowadays, the agriculture’s target is to reach the amount of crop production that can cover the need to feed growing world population with the crucial challenge of respecting the environment. Several environmental constraints are limiting world agricultural production, mainly the preponderance of calcareous soils suffering from ferric and phosphoric deficiencies. In those soils, legumes were considered as an alternative solution to retrieve a fertile soil without the abusive use of chemical fertilizers. The ability to establish a symbiotic association with nitrogen-fixing soil bacteria is the way used by legumes to restore soil organic matter and to improve soil fertility. Legumes remain a source of healthy food while respecting the environment. This paper describes the importance of legumes for Fe and P deficient soils management through sustainable practices.

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