The microbial siderophore desferrioxamine B inhibits Fe and Zn uptake in three spring wheat genotypes grown in Fe-deficient nutrient solution

Abstract

While phytosiderophores (PS) are known to chelate Fe, the role that microbial siderophores play in iron and zinc transport in graminaceous plants has not been sufficiently investigated. The aim of this study was to assess the influence of the microbial siderophore DFOB (desferal, desferrioxamine B) in Fe and Zn transport and chlorosis resistance in three hard red spring wheat genotypes (Triticum aestivum L. cvs. 2375, Marquis, and Waldron). Plants were grown in Fe deficient nutrient solutions containing two DFOB levels (0 and 30 µM) for 6 weeks. Phytosiderophore concentrations were determined after 1, 2, 4 and 6 weeks of Fe deficiency. After 6 weeks plants were harvested and separated to root and shoot tissue to determine the dry matter and Fe and Zn content of the genotypes. There was no positive relationship between the amount of phytosiderophore exudation and differential tolerance of the wheat genotypes to Fe deficiency. Across most weeks, Fe-inefficient genotypes, Marquis and 2375, had no significant difference in the rate of phytosiderophore exudation compared to Fe-efficient genotype, Waldron, and only at 6 weeks in -DFOB treatment and 4 weeks in + DFOB treatment Waldron had a significantly higher rate of phytosiderophore exudation compared to Marquis and 2375. These findings suggested that mechanisms other than phytosiderophores might be involved in Fe deficiency tolerance of the wheat genotypes. There was not a strong correlation between phytosiderophore secretion and Fe and Zn transport to shoots of the studied wheat genotypes. Even though in most weeks Fe-inefficient genotype, Marquis, had the lowest phytosiderophore exudation among the studied genotypes, its ability to transport Fe and Zn to shoot was higher than Fe-efficient genotype, Waldron. These results also revealed that the relationship between Fe and Zn transport and tolerance to Fe deficiency was poor. Addition of DFOB decreased overall tolerance to Fe deficiency of the wheat genotype. In general, DFOB decreased Fe and Zn transport to the shoots of the Marquis and Waldron genotypes and only Zn transport to the shoots of the 2375 genotype. Further studies are needed to investigate the ability of these chelators in tolerance to Fe deficiency and Fe and Zn transport to shoot of wheat genotypes