Physiological Limits to Zinc Biofortification of Edible Crops

Summary

White and Broadley review the physiological constraints limiting zinc biofortification of edible crops, demonstrating that whilst root and leaf zinc concentrations can reach 500–5000 and 100–700 mg kg⁻¹ dry matter respectively through soil-applied fertilisers, zinc concentrations in fruits, seeds, and tubers are severely constrained by low phloem mobility, rarely exceeding 30–100 mg kg⁻¹ dry matter. The authors propose that genetic modification to enhance phloem zinc translocation or tolerance to high tissue zinc could overcome these limitations and improve dietary zinc intakes in populations.

Regional applicability

The findings are globally applicable to zinc biofortification efforts across the United Kingdom and internationally. UK crop production and breeding programmes pursuing micronutrient biofortification would need to account for these physiological constraints, particularly when targeting seed and fruit crops where phloem limitation is most pronounced.

Key measures

Zinc concentrations (mg kg⁻¹ dry matter) in roots, leaves, stems, fruits, seeds, and tubers; phloem mobility; tissue-specific accumulation capacity

Outcomes reported

The study examined zinc concentrations achievable in different crop tissues (roots, leaves, stems, fruits, seeds, tubers) through fertiliser application and genetic approaches, identifying physiological limits to biofortification in phloem-fed tissues.

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