Differential expression of iron transporters in Amaranthus cruentus roots when are subjected to salt stress: The influence of root endophytes

Abstract

Salt-stress is one the main abiotic factors that negatively affect plant growth leading to crop losses throughout the world. Amaranth (Amaranthus L.) is a plant with outstanding agronomic properties and can grow under several environmental stresses including salinity. But, despite its agronomic qualities, molecular changes in plants subjected to salt stress are not well studied. Plant roots are the primary sensors responsible for sensing the rhizosphere conditions to adjust the adequate nutrient uptake for plant growth, and they also house endophytic microbes that play important roles in plant growth promotion. In this work, suppression subtractive hybridization libraries from amaranth roots growing under control conditions and in plants exposed to 150 mM NaCl were constructed. Identified differential expressed sequences tags (EST) were related with Fe, Mo, and amino acids transport, interestingly those EST showed high homology with bacterial sequences. Bacterial endophytes were isolated and identified by 16S ARNr gene sequencing. Under control conditions culturable diazotrophic endophytes were mainly composed by Pseudomonas and Variovorax, while under salt stress were Pseudomonas, Kosakonia, and Enterobacter. Most of the isolated bacteria were able to produce siderophores, solubilize phosphates, and showed the ability to grow under high NaCl conditions. These results open new venues on the relevance of amaranth endophytes on salt-stress tolerance.