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To understand the salinity tolerance mechanism in faba bean contrasting pair to salinity (cv. Chourouk as sensitive and cv. Najeh as tolerant), we evaluated the effect of high salt concentration (150 mM NaCl) on the photosynthetic, physiological, and biochemical parameters at short and long term of treatment (1 and 6 days, respectively) in the seedling stage. In general, the salinity affects the growth of plants. High salinity decreased all studied parameters, especially transpiration rate (E), stomatol conductance (gs), net CO2 assimilation (A), and substomatal CO2 concentration (Ci), and dramatic changes was registered in cv. Chourouk compared to cv. Najeh. Chlorophyll contents were also affected by salinity, especially in the sensitive variety. In addition, the synthesis of osmolytes (proline) was determinate, to understand whether the osmotic adjustment is a mechanism used by cv. Najeh to tolerate salt stress. Our research suggests that cv. Najeh should be introduced in a crossbreeding program as an elite salt-tolerant germplasm.

Context Heavy metal contamination of soils is a serious environmental problem worldwide. Cadmium (Cd) and lead (Pb) are considered among the most important types of pollutants. Aim To investigate the response of a local fenugreek cultivar against lead and cadmium. Methods Physiological changes were studied under different concentrations (0, 100, 200, 300 and 400 μM) of PbCl2 and CdCl2. Key results Fenugreek growth decreased gradually with increasing Cd and Pb supply. This decrease was accompanied by a gradual decline in shoot and root length and photosynthetic parameters. However, Cd treatments showed pronounced effects in fenugreek seedlings as compared to Pb. The tolerance index was between 0.41 and 0.81, which suggests relative tolerance of this cultivar to Pb and Cd. This species was also able to maintain stable water status. Nevertheless, in presence of high Cd concentration (400 μM), this species showed substantial decrease in CO2 assimilation (86%), transpiration rate (87%), stomatal conductance (57%), chlorophyll content (35%) and carotenoid content (53%). Shoot proline content was increased significantly under 200 and 300 μM Cd, and slightly under 100 and 200 μM Pb. Furthermore, Cd and Pb induced a decrease in shoot magnesium and phosphorus content. Conversely, shoot iron content was increased. Data showed that fenugreek accumulated Cd, and translocated to the harvestable parts (up to 20 mg/kg DW under 400 μM). However, Pb was mostly accumulated in roots. Conclusions Our results revealed that the relative tolerance of fenugreek to Pb excess was coupled to a remarkable accumulation of this element in root, which favourite the phytostabilisation process. Implications FM, FL, SJ and OTZ execute the manipulation and the culture of plants. FM, OTZ, IN and KZ analyse and examine obtained results. FM, OTZ and KZ write and preparethe manuscript. IN, HM and KZ prepare the conception and the realisation ofthis work.

Drought is an environmental stress that strongly impacts plants. It affects all stages of growth and induces profound disturbances that influence all cellular functions. Legumes can establish a symbiosis with Rhizobium-type bacteria, whose function is to fix atmospheric nitrogen in organs called nodules and to meet plant nitrogen needs. Symbiotic nitrogen fixation (SNF) is particularly sensitive to drought. We raised the hypothesis that, in drought-stressed nodules, SNF inhibition is partly correlated to hypoxia resulting from nodule structure compaction and an increased O2 diffusion barrier, and that the nodule energy regeneration involves phytoglobin–nitric oxide (Pgb–NO) respiration. To test this hypothesis, we subjected faba bean (Vicia faba L.) plants nodulated with a Rhizobium laguerreae strain to either drought or osmotic stress. We monitored the N2-fixation activity, the energy state (ATP/ADP ratio), the expression of hypoxia marker genes (alcohol dehydrogenase and alanine aminotransferase), and the functioning of the Pgb–NO respiration in the nodules. The collected data confirmed our hypothesis and showed that (1) drought-stressed nodules were subject to more intense hypoxia than control nodules and (2) NO production increased and contributed via Pgb–NO respiration to the maintenance of the energy state of drought-stressed nodules.

The characterization of PR10 proteins has been conducted in many plant species. However, little is known about the roles of PvPR10 in response of common bean (Phaseolus vulgaris L.) to stress. Thus, for the first time a genome wide analysis revealed that the 34 genes of Bet v 1 family were divided into three major subfamilies according to phylogenetic relationship analysis from P. vulgaris and other plant species. The analysis uncovered that tandem duplication was the major force in the expansion of the Bet v 1 family genes in P. vulgaris and two other Fabaceae plants. Furthermore, the gene structure and motifs examination revealed that genes of Bet v 1 family were relatively conserved during evolution. Likewise, we recognized in the PvPR10 promoter regions several cis-regulatory elements related not only to abiotic and biotic stresses but also to phytohormones. In P. vulgaris, several PvPR10 genes exhibited differential expression profiles in many developmental tissues and organs. Notably, the expression profiles showed that essentially the two genes PvPR10-2 and PvPR10-3 genes were up-regulated under various treatments. Besides, the combined NaCl-JA stress enhanced their expressions in leaves and stems. Finally, we noticed that these inductions seem to be correlated with the enhancement of the expression of ABA biosynthesis PvNCED3 gene and the transcription factor PvDREB. Taken together, these data provide a foundation for further functional studies of certain PvPR10 that could be used in various stress tolerance improvements.

The aim of this study was to evaluate the effect of the addition of biochar (0, 2, 5, and 8% designed by C, B2, B5, and B8, respectively) on the single and interactive effects of salinity and drought treatments on the growth of vicia faba plants in alkaline soil. 21 morphological, physiological, and photosynthetic parameters were evaluated. The amendment of biochar, carbon-rich material developed from combustion of biomass under no or limited oxygen supply, in alkaline soil under salinity stress performed positive effects on internal concentration of CO2 (+ 96.16% at B8), transpiration rate (+ 83.79% at B5), stomatal conductance (+ 30% at B2), and net CO2 assimilation (+ 37.84% at B2). Under drought stress, the addition of biochar had no effect on internal concentration of CO2 and the water use efficiency. Under combined conditions, the maximum increase (+ 40%) of internal concentration of CO2 was registered at B5. Also, addition of 2% of biochar (B2) can increase the transpiration rate to + 116%. Biochar was alleviating the effect of combined stress on vicia faba leaves by ameliorating the stomatal conductance to + 58.73% at B2. We, also, noticed that net CO2 assimilation rate increase with the increase of biochar concentration. On the other hand, biochar addition did not have effect on lengths of shoot, roots, and total plants and fresh biomass, spad value, and leaf number. However, the amendment of biochar has slightly ameliorated the electrolyte leakage, protein content, and foliar surface. The pH and the EC of initial and final treatment were also evaluated. The statistical analysis demonstrates that addition of 2% (B2) of biochar can significantly mitigate the negative effect of single effect of salinity and combined salinity drought in alkaline soil. On the other hand, the addition of 5% (B5) of biochar can alleviate the individual effect of drought compared to their respective controls. This result confirms the positive effect of biochar addition in alkaline soils. Thus, a better understanding of biochar addition on physiological basis for faba bean growth under drought and salinity stress in alkaline soil will be beneficial for sustainable agriculture.