Rice wild relatives (RWR) constitute an extended gene pool that can be tapped for the breeding of novel rice varieties adapted to abiotic stresses such as iron (Fe) toxicity. Therefore, we screened 75 Oryza genotypes including 16 domesticated O. sativa genotypes, one O. glaberrima, and 58 RWR representing 21 species, for tolerance to Fe toxicity. Plants were grown in a semi-artificial greenhouse setup, in which they were exposed either to control conditions, an Fe shock during the vegetative growth stage (acute treatment), or to a continuous moderately high Fe level (chronic treatment). In both stress treatments, foliar Fe concentrations were characteristic of Fe toxicity, and plants developed foliar stress symptoms, which were more pronounced in the chronic Fe stress especially toward the end of the growing season. Among the genotypes that produced seeds, only the chronic stress treatment significantly reduced yields due to increases in spikelet sterility. Moreover, a moderate but non-significant increase in grain Fe concentrations, and a significant increase in grain Zn concentrations were seen in chronic stress. Both domesticated rice and RWR exhibited substantial genotypic variation in their responses to Fe toxicity. Although no RWR strikingly outperformed domesticated rice in Fe toxic conditions, some genotypes scored highly in individual traits. Two O. meridionalis accessions were best in avoiding foliar symptom formation in acute Fe stress, while an O. rufipogon accession produced the highest grain yields in both chronic and acute Fe stress. In conclusion, this study provides the basis for using interspecific crosses for adapting rice to Fe toxicity. , et al.(2020) Evaluation of rice wild relatives as a source of traits for adaptation to iron toxicity and enhanced grain quality. PLoS ONE 15(1): e0223086. https://doi.org/10.

20Rice wild relatives (RWR) constitute an extended gene pool that can be tapped for the breeding of novel 21 rice varieties adapted to abiotic stresses such as iron (Fe) toxicity. Therefore, we screened 75 Oryza 22 genotypes including 16 domesticated O. sativas, one O. glaberrima, and 58 RWR representing 21 23 species, for tolerance to Fe toxicity. Plants were grown in a semi-artificial greenhouse setup, in which 24 they were exposed either to control conditions, an Fe shock during the vegetative growth stage (acute 25 treatment), or to a continuous moderately high Fe level (chronic treatment). In both stress treatments, 26 foliar Fe concentrations were characteristic of Fe toxicity, and plants developed foliar stress symptoms, 27which were more pronounced in the chronic Fe stress especially toward the end of the growing season. 28Among the genotypes that produced seeds, only the chronic stress treatment significantly reduced 29 yields due to increases in spikelet sterility. Moreover, a moderate but non-significant increase in grain Fe 30 concentrations, and a significant increase in grain Zn concentrations were seen in chronic stress. Both 31 domesticated rice and RWR exhibited substantial genotypic variation in their responses to Fe toxicity. 32Although no RWR strikingly outperformed domesticated rice in Fe toxic conditions, some genotypes 33 scored highly in individual traits. Two O. meridionalis accessions were best in avoiding foliar symptom 34 formation in acute Fe stress, while an O. rufipogon accession produced the highest grain yields in both 35 chronic and acute Fe stress. In conclusion, this study provides the basis for using interspecific crosses for 36 adapting rice to Fe toxicity. 37