18th International Symposium on Iron Nutrition and Interaction in Plants
Madrid – May 30-June 3 2016
DFFERENTIAL RESPONSE TO IRON DEFICIENCY WITHIN TUNISIAN MEDICAGO
TRUNCATULA GENOTYPES
Nadia Kallala, Wissal M’sehli*, Haytham Mhadhbi
Laboratory of Legumes, Centre of Biotechnology of Borj-Cedria, Hammam-Lif, Tunisia
*corresponding autor: [email protected]
Iron (Fe) deficiency is an important environmental factor restricting plant productivity particularly when
alkaline or calcareous soils are concerned. Selecting tolerant genotypes is one of the possible ways to solve
this nutritional problem. The aim of this work was to compare the tolerance to Fe deficiency of four Medicago
truncatula genotypes (Jemalong A17, TN8.20, TN6.18 and TN1.11) to identify contrasting genotypes for
tolerance mechanisms’ investigation.
Three treatments were used: complete medium containing (C, + 50 µM Fe); direct deficiency (DD, + 5 µM
Fe); induced deficiency (ID, + 50 µM Fe + 10 mM Bicarbonate). Assessment of Fe deficiency effects was
performed mainly on plant vigor and morphology, biomass production, photosynthesis apparatus, Fe status,
Fe (III)-chelate-reductase activity and antioxidant systems.
Our results showed that Fe deprivation had a lowering effect on general plant vigor aspect, biomass
production, photosynthesis apparatus (chlorophyll and chlorophyll fluorescence) and Fe status of all treated
plants. Negative effects were more pronounced in TN1.11 and TN6.18 genotypes than in Jemalong A17 and
TN8.20 ones. Indeed, the observed decrease in biomass production caused by direct iron deficiency is three
time higher in TN1.11 genotype (-78%) than in TN8.20 one (-24%). Overall, the relatively better tolerance of
Jemalong A17 and TN8.20 to both direct and bicarbonate-induced Fe deficiency was positively correlated to
the capacity of these genotypes to maintain higher Fe acquisition efficiency via Fe (III)-chelate-reductase
activity in concomitance with a larger root system. The tolerant genotypes showed also higher antioxidant
capacity revealed in stimulated activities of catalase (CAT) and peroxidase (GPOX) enzymes as well as
polyphenols under this nutritional stress. Spectacularly, plyophenols content was 100 % increased in roots of
TN8.20 genotype under direct Fe deficiency; however it was decreased (-17%) in TN1.11 roots.
Key words: Genotypic variability, Iron deficiency, Medicago truncatula, Tolerance mechanisms
.
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