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The Contribution of Zn Uptake and Grain Zn Loading Intensity to Achieving Zn Biofortification Breeding Targets in Rice

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Title: The Contribution of Zn Uptake and Grain Zn Loading Intensity to Achieving Zn Biofortification Breeding Targets in Rice
Authors: Rakotondramanana, Mbolatantely, Stangoulis, James, Grenier, Cécile, Wissuwa, Matthias
Contributors: RIOU, Christine
Source: Journal of Plant Nutrition and Soil Science
Publisher Information: Wiley, 2025.
Publication Year: 2025
Subject Terms: grain zinc, zinc translocation, [SDV.SA.STA] Life Sciences [q-bio]/Agricultural sciences/Sciences and technics of agriculture, Oryza sativa, fertilisation, genotypic variation, [SDV.GEN.GPL] Life Sciences [q-bio]/Genetics/Plants genetics, biomasse, zinc concentrations, essai de variété, grain, riz, [SDV.SA] Life Sciences [q-bio]/Agricultural sciences, variété, zinc, gene-bank accessions, légume racine, [SDV.BV.AP] Life Sciences [q-bio]/Vegetal Biology/Plant breeding, génotype, amélioration des plantes, expression des gènes
Description: BackgroundIncreasing Zinc (Zn) concentrations in rice grains is targeted in Zn‐biofortification breeding but most rice varieties have grain Zn concentrations far below breeding targets.AimsHigh‐Zn donors have been identified and our aim is to investigate whether higher grain Zn concentrations in these donors were the result of superior Zn uptake during the reproductive stage, of higher Zn loading intensities or caused by an extended Zn loading period.MethodsField experiments comparing two high‐Zn donors to two low‐Zn modern varieties were conducted over two seasons in Madagascar and tissue Zn concentrations and content determined from heading to maturity.ResultsZn uptake between heading and maturity was not limiting grain Zn concentrations. Neither did studied genotypes differ significantly in the duration of Zn loading, which peaked 8–12 days after flowering and strongly decreased thereafter, even in high‐Zn donors. Instead, the Zn loading intensity during grain filling differed with peak loading rates exceeding 60 ng Zn day−1 in high‐Zn donors compared to 13–37 ng Zn day−1 in low‐Zn varieties. This high Zn loading intensity was further evident when Zn and biomass grain loading rates were compared. Donor IRIS‐9368 loaded up to 40 ng Zn mg−1 grain biomass compared to 12–21 ng Zn mg−1 in low‐Zn varieties. This high loading intensity resulted in a zinc harvest index of 47.7% in IRIS‐9368 compared to 26.1% for local variety X265 despite similar reproductive‐stage Zn uptake.ConclusionsWe hypothesize that xylem‐to‐phloem transfer of Zn at upper nodes is more efficient in high‐Zn donor IRIS‐9368.
Document Type: Article
File Description: text; application/pdf
Language: English
ISSN: 1522-2624
1436-8730
DOI: 10.1002/jpln.12013
Access URL: http://agritrop.cirad.fr/613112/
https://hal.inrae.fr/hal-05058393v2
https://doi.org/10.1002/jpln.12013
https://hal.inrae.fr/hal-05058393v2/document
Rights: CC BY
Accession Number: edsair.doi.dedup.....74f986b3ff11a5cda98a738da99e0919
Database: OpenAIRE
Description
Abstract:BackgroundIncreasing Zinc (Zn) concentrations in rice grains is targeted in Zn‐biofortification breeding but most rice varieties have grain Zn concentrations far below breeding targets.AimsHigh‐Zn donors have been identified and our aim is to investigate whether higher grain Zn concentrations in these donors were the result of superior Zn uptake during the reproductive stage, of higher Zn loading intensities or caused by an extended Zn loading period.MethodsField experiments comparing two high‐Zn donors to two low‐Zn modern varieties were conducted over two seasons in Madagascar and tissue Zn concentrations and content determined from heading to maturity.ResultsZn uptake between heading and maturity was not limiting grain Zn concentrations. Neither did studied genotypes differ significantly in the duration of Zn loading, which peaked 8–12 days after flowering and strongly decreased thereafter, even in high‐Zn donors. Instead, the Zn loading intensity during grain filling differed with peak loading rates exceeding 60 ng Zn day−1 in high‐Zn donors compared to 13–37 ng Zn day−1 in low‐Zn varieties. This high Zn loading intensity was further evident when Zn and biomass grain loading rates were compared. Donor IRIS‐9368 loaded up to 40 ng Zn mg−1 grain biomass compared to 12–21 ng Zn mg−1 in low‐Zn varieties. This high loading intensity resulted in a zinc harvest index of 47.7% in IRIS‐9368 compared to 26.1% for local variety X265 despite similar reproductive‐stage Zn uptake.ConclusionsWe hypothesize that xylem‐to‐phloem transfer of Zn at upper nodes is more efficient in high‐Zn donor IRIS‐9368.
ISSN:15222624
14368730
DOI:10.1002/jpln.12013