Introgression fromOryza meridionalisinto domesticated riceOryza sativaresults in shoot-based iron tolerance

Abstract

AbstractIron (Fe) toxicity is one of the most common mineral disorders affecting rice (Oryza sativa) production in flooded lowland fields.Oryza meridionalisis endemic from Northern Australia and grows in regions with Fe rich soils, making it a candidate for use in adaptive breeding. Aiming to understand tolerance mechanisms in rice, we screened a population of interspecific introgression lines (IL) from a cross betweenO. sativaandO. meridionalisfor the identification of QTLs contributing to Fe toxicity tolerance. Six putative QTLs were identified. A line carrying one introgression fromO. meridionalison chromosome 9 associated with one QTL was highly tolerant despite very high shoot Fe concentrations. Physiological, biochemical, ionomic and transcriptomic analyses showed that the IL tolerance could partly be explained by Fe retention in the leaf sheath and culm. We constructed the interspecific hybrid genomein silicofor transcriptomic analysis, and identified differentially regulated introgressed genes fromO. meridionalisthat could be involved in shoot-based Fe tolerance, such as metallothioneins, glutathione S-transferases and transporters from ABC and MFS families. This is the first work to demonstrate that introgressions ofO. meridionalisinto theO. sativagenome can confer increased tolerance to excess Fe.HighlightWe identified QTLs associated with iron tolerance derived fromO. meridionalis, and characterized their physiological basis inO. sativa.