Pseudomonas simiae WCS417 and Debaryomyces hansenii Induce Iron Deficiency Responses in Rice (Oryza sativa L.)...

Iron (Fe) is an essential micronutrient for crop productivity, but its low availability in alkaline and calcareous soils limits the growth of rice (Oryza sativa L.), which employs a combined strategy for its acquisition based on the release of phytosiderophores (PS) and the use of specific transporters. In this study, the effect of the rhizospheric bacterium Pseudomonas simiae WCS417 and the halotolerant yeast Debaryomyces hansenii CBS767 as inducers of responses to Fe deficiency in rice grown under hydroponic conditions was evaluated. Plants were inoculated in nutrient solutions with and without Fe, and PS production and the expression of genes associated with biosynthesis and transport were determined by qRT-PCR. The results showed that both microorganisms significantly increased PS production compared to controls, especially under Fe-deficient conditions, although P. simiae also exerted an effect under Fe sufficiency. Furthermore, induction of key genes (OsNAAT, OsIRO2, OsTOM1, OsYSL15, and OsIRT1), as well as genes related to the ethylene pathway (OsEIN2, OsACS2, and OsACO3), was observed, pointing to a regulatory role for this hormone in the response. In conclusion, P. simiae and D. hansenii act as inducers of Fe acquisition mechanisms in rice, offering a sustainable biotechnological approach to improve iron nutrition in limiting environments.