Mechanisms of genotypic differences in tolerance of iron toxicity in field-grown rice

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dc.contributor.authorRajonandraina, Toavintsoa
dc.contributor.authorRakotoson, Tovohery
dc.contributor.authorWissuwa, Matthias
dc.contributor.authorUeda, Yoshiaki
dc.contributor.authorRazafimbelo, Tantely
dc.contributor.authorAndriamananjara, Andry
dc.contributor.authorKirk, Guy J. D.
dc.date.accessioned2023-05-22T13:01:08Z
dc.date.available2023-05-22T13:01:08Z
dc.date.issued2023-04-28
dc.description.abstractIron (Fe) toxicity is a major constraint to rice yields in much of the world due to the greater solubility of reduced ferrous Fe in paddy soils compared with ferric Fe in aerobic soils and resulting excess uptake into the plants. There is genotypic variation in tolerance in Oryza gene pools, but so far only weak-effect alleles have been identified, largely because multiple critical physiological processes determine the tolerance. Most past research has been done in nutrient solution screens at the seedling stage, and not under field conditions over the full life cycle. We investigated tolerance mechanisms in a diverse set of genotypes under field conditions in a highly iron toxic soil in the Central Highlands of Madagascar. We made repeated plant samplings of young and old tissues throughout the growth period until maturity. Multiple mechanisms were involved, and the importance of different mechanisms changed between growth stages. Higher grain yields were mainly due to healthy vegetative growth, achieved either by reducing Fe uptake (exclusion) or by minimizing the effect of excess uptake through compartmentalization in older tissues and tissue tolerance. Exclusion mechanisms were relaxed during reproductive growth, leading to increased Fe accumulation in shoots. But tolerant genotypes were nonetheless able to grow well through a combination of Fe compartmentalization and tissue tolerance, so that grain filling could proceed relatively unimpeded. Tissue phosphorus (P) and potassium (K) concentrations were close to or below deficiency limits throughout growth. Exclusion by ferrous Fe oxidation in the rhizosphere will impede access of P and K ions to roots, but the differences in their tissue concentrations were much smaller than differences in growth rates, so growth rates evidently drove the uptake differences and responses to Fe toxicity were the more important constraints. There was no relation between grain yield and visual symptoms. To identify useful donors and markers for breeding it is important to develop screening protocols that capture the individual tolerance mechanisms, allowing for the effects of growth stage on their relative importance and expression, and possible interactions with other factors such as mineral nutrition. Selection for tolerance based on visual symptoms, particularly at the seedling stage, is overly simplistic, though it can be useful in the study of specific tolerance mechanisms.en_UK
dc.identifier.citationRajonandraina T, Rakotoson T, Wissuwa M, et al., (2023) Mechanisms of genotypic differences in tolerance of iron toxicity in field-grown rice. Field Crops Research, Volume 298, July 2023, Article number 108953en_UK
dc.identifier.issn0378-4290
dc.identifier.urihttps://doi.org/10.1016/j.fcr.2023.108953
dc.identifier.urihttps://dspace.lib.cranfield.ac.uk/handle/1826/19688
dc.language.isoenen_UK
dc.publisherElsevieren_UK
dc.rightsAttribution 4.0 International*
dc.rights.urihttp://creativecommons.org/licenses/by/4.0/*
dc.subjectGenotypic stress toleranceen_UK
dc.subjectIron toxicityen_UK
dc.subjectMineral nutritionen_UK
dc.subjectOryza spp.en_UK
dc.subjectRhizosphereen_UK
dc.subjectRiceen_UK
dc.subjectSubmerged paddy soilsen_UK
dc.titleMechanisms of genotypic differences in tolerance of iron toxicity in field-grown riceen_UK
dc.typeArticleen_UK

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