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Background and aims <p>Pepper (<i>Capsicum annuum</i> L.) is rich in micronutrients, but genotypic variation in fruit iron (Fe) and zinc (Zn) concentrations remains poorly characterized. This study compared two pepper varieties (XL111 and XL1) under contrasting Fe and Zn supply to elucidate the physiological and molecular mechanisms responsible for differences in Fe and Zn acquisition and fruit accumulation.</p> Methods <p>Root morphology, biomass (root, shoot, fruit), and Fe/Zn accumulation in fruits were measured in pot experiments under control (CK), Fe–deficient (-Fe), and Zn–deficient (–Zn) conditions. Parallel hydroponic experiments with the same treatments were used to determine Fe and Zn uptake kinetics (Imax, Km, Cmin) and root transcriptome profiles of key transporter genes. These approaches collectively elucidated the mechanisms of efficient Fe/Zn acquisition in the superior variety.</p> Results <p>XL111 exhibited 13.6% higher Fe and 33.5% higher Zn concentrations in fruits, with 24.2% and 37.5% greater total accumulation, respectively, compared to XL1. XL111 also exhibited 20%-30% greater root length and root surface area, higher Imax (0.5-2 folds) and lower Cmin (20%-50% reduction) for both nutrients. Transcriptome analysis revealed XL111 showed stronger upregulation of Fe–related transporters (<i>NRAMP1, ZIP2, ZIP3, ABCB, ABC10, FRO2, FRO3</i>) and Zn–related transporters (<i>YSL1, VIT1, ZIP11</i>) under nutrient deficiency.</p> Conclusion <p>The superior Fe/Zn efficiency of XL111 arises from enhanced root architectural plasticity, improved uptake kinetics, and stronger transcriptional activation of metal transporters under deficiency. These traits provide targets for breeding and nutrient acquisition strategies in nutrient–limited environments.</p> Graphical Abstract <p>Conceptual model describing differences in root morphology, Fe and Zn uptake capacity, relative expression of Fe and Zn uptake and transport associated genes, and photosynthetic capacity of two pepper varieties XL111 and XL1 grown under high and low Fe/Zn concentration. The blue and red arrows indicate the efficient and inefficient levels of the corresponding indicators, respectively.</p> <p></p>

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Unraveling iron and zinc efficiency in pepper: integration of root architecture, uptake kinetics, and transcriptional regulation

  • 期刊论文

  • 发表日期：

    2026年2月25日

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  • Cheng-Xiang Zhou,
  • Wei Zhang,
  • Bao-Gang Yu,
  • Hao-Feng Yang,
  • Yuan Wang,
  • Kai Sun,
  • Fu-Lin Zhao,
  • Huai-Yu Yang,
  • Prakash Lakshmanan,
  • Xin-Ping Chen,
  • Chun-Qin Zou

摘要

Background and aims

Pepper (Capsicum annuum L.) is rich in micronutrients, but genotypic variation in fruit iron (Fe) and zinc (Zn) concentrations remains poorly characterized. This study compared two pepper varieties (XL111 and XL1) under contrasting Fe and Zn supply to elucidate the physiological and molecular mechanisms responsible for differences in Fe and Zn acquisition and fruit accumulation.

Methods

Root morphology, biomass (root, shoot, fruit), and Fe/Zn accumulation in fruits were measured in pot experiments under control (CK), Fe–deficient (-Fe), and Zn–deficient (–Zn) conditions. Parallel hydroponic experiments with the same treatments were used to determine Fe and Zn uptake kinetics (Imax, Km, Cmin) and root transcriptome profiles of key transporter genes. These approaches collectively elucidated the mechanisms of efficient Fe/Zn acquisition in the superior variety.

Results

XL111 exhibited 13.6% higher Fe and 33.5% higher Zn concentrations in fruits, with 24.2% and 37.5% greater total accumulation, respectively, compared to XL1. XL111 also exhibited 20%-30% greater root length and root surface area, higher Imax (0.5-2 folds) and lower Cmin (20%-50% reduction) for both nutrients. Transcriptome analysis revealed XL111 showed stronger upregulation of Fe–related transporters (NRAMP1, ZIP2, ZIP3, ABCB, ABC10, FRO2, FRO3) and Zn–related transporters (YSL1, VIT1, ZIP11) under nutrient deficiency.

Conclusion

The superior Fe/Zn efficiency of XL111 arises from enhanced root architectural plasticity, improved uptake kinetics, and stronger transcriptional activation of metal transporters under deficiency. These traits provide targets for breeding and nutrient acquisition strategies in nutrient–limited environments.

Graphical Abstract

Conceptual model describing differences in root morphology, Fe and Zn uptake capacity, relative expression of Fe and Zn uptake and transport associated genes, and photosynthetic capacity of two pepper varieties XL111 and XL1 grown under high and low Fe/Zn concentration. The blue and red arrows indicate the efficient and inefficient levels of the corresponding indicators, respectively.