Biodiversity within Medicago truncatula genotypes toward response to iron deficiency: Investigation of main tolerance mechanisms

Abstract

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.

Plant Iron Research in African Countries: Current “Hot Spots”, Approaches, and Potentialities

“…Twenty genotypes of barrel medic ( Medicago truncatula ), a small annual legume used as forage but also as a model plant, were screened for their physiological response to Fe deficiency during growth. Fe deficiency-tolerant and -sensitive genotypes were identified; tolerance was correlated with greater acidification capacity, modified root architecture, and an induction of Superoxide Dismutase (SOD) activities [ 63 , 64 ]. Similar approaches were applied to investigate genotypic differences in the response to Fe deficiency in pea [ 51 , 52 ] and in common bean [ 37 ].…”

“…Publications with African Prominent Authorship pea (Pisum sativum) [51,52] [ 51,52] tomato (Solanum lycopersicum) [53][54][55] [ [53][54][55] sorghum (Sorghum bicolor) [56][57][58] [ 57,58] lentil (Lens culinaris) [59,60] wheat (various species) [61,62] [ 61,62] barrel medic (Medicago truncatula) [63,64] [ 63,64] cowpea (Vigna unguiculata) [33,65] [ 33,65] broad bean (Vicia faba) [66,67] [ 66,67] barley (Hordeum vulgare) [68] [68] flax (Linum usitatissimum) [69] date palm (Phoenix dactylifera) [70] grey mangrove (Avicennia marina) [71] African wormwood (Artemisia afra) [ To further restrict our analysis to research prominently conducted in Africa, only 48 publications were retained for further analysis, i.e., those with first and/or corresponding authors affiliated with an African country (Table 1, plant species and references in bold). Hence, 22 papers were excluded, as they either did not report an African affiliation as a prominent authorship [15,19,20,27,…”

Legumes: Model Plants for Sustainable Agriculture in Phosphorus and Iron Deficient Soils

“…In a complimentary study, M'sehli et al, (2011) have studied the tolerance of two lines of Medicago ciliaris (TN11.11 and TN8.7) to Fe deficiency and found that TN11.11 line has a potential to enhance revegetation in calcareous soils for pastoral use. In addition, Kallala et al (2019) carried out a study 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. Based on biometric and physiological markers, those authors found a biodiversity among the 20 genotypes studied toward tolerance to iron deficiency.…”

“…It has been demonstrated that symbiotic nitrogen fixation and ammonium assimilation induce soil acidification and therefore increase of Fe bioavailability (Pii et al, 2015). Kallala et al (2019) showed that the inoculation of Medicago truncatula genotypes with two Sinorhizobium strains ameliorates the tolerance of Fe-deficient plants to Fe starvation. Theses authors stated also that both Sinorhizobium strains (TII7 and SII4) stimulates the antioxidant enzyme activities in Fe-deficient plants.In addition, rhizobia can also produce strain specific siderophores that can help overcome iron starvation (Bargaz et al, 2015).…”

Legumes: Model Plants for Sustainable Agriculture in Calcareous Soils

“…In a complimentary study, [19] have studied the tolerance of two lines of Medicago ciliaris (TN11.11 and TN8.7) to Fe deficiency and found that TN11.11 line has a potential to enhance revegetation in calcareous soils for pastoral use. In addition, a study was carried out by [20] 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. Based on biometric and physiological markers, those authors found a biodiversity among the 20 genotypes studied toward tolerance to iron deficiency.…”