Effect of Fe deficiency on alfalfa plants grown in the presence of Pseudomonas

Abstract

Alfalfa is a model plant defined as less sensitive than others to iron (Fe) deficiency. In the present work, some mechanisms induced in low Fe availability conditions were studied, including the effect of inoculation of alfalfa seeds with Pseudomonas putida. The effect of different Fe contents in the nutrient solution on the growth parameters was evaluated at 3 and 10 days, observing that low Fe conditions promoted biomass accumulation. Activation in the mechanisms of Fe acquisition, through acidification of the media and an increase in the ferric chelate reductase (FCR) activity, was observed in the absence of Fe at 10 days. The presence of P. putida KT2442 in the rhizosphere eliminated FCR activation through the excretion of siderophores. The effect of the siderophores on the modulation of FCR activity was demonstrated using a ppsD mutant strain, unable to segregate them, observing an activation of the activity similar to that observed in the absence of the bacteria. This, together with the demonstrated mechanisms to increase Fe availability, contributed to the conclusion that alfalfa can be used for recovery programmes of soils with low Fe availability.