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Key message <p><b>Rice genotypes differ in aluminium tolerance, with resistant landraces sustaining root growth</b> <Emphasis Type="BoldItalic">OsSTAR1</Emphasis><b>&#xa0;/&#xa0;</b><Emphasis Type="BoldItalic">OsSTAR2</Emphasis>&#xa0;<b>mediated exclusion, organic acid efflux, and antioxidant defense, whereas sensitive varieties accumulate Al³⁺ via</b> <Emphasis Type="BoldItalic">OsNRAT1</Emphasis><b>–</b><Emphasis Type="BoldItalic">OsALS1</Emphasis> <b>mediated internal sequestration, leading to oxidative damage.</b></p> Abstract <p>This study reveals two contrasting molecular strategies of aluminium (Al) tolerance&#xa0;root-based exclusion and internal detoxification&#xa0;among indigenous rice landraces of Northeast India, a region severely affected by acidic soil-related Al toxicity. Fifty-three rice genotypes were evaluated under hydroponic Al stress (200&#xa0;μM AlCl₃) through integrated morphophysiological, biochemical, and gene expression analyses. Tolerant genotypes such as Ahom Sali and Disang sustained root growth, biomass, and relative water content, whereas sensitive types such as Ranjit Sub-1 and Jolkonwari showed severe root inhibition and oxidative damage. SSR marker analysis of 33 polymorphic loci (mean PIC = 0.48) confirmed high genetic diversity, but weak correlation with phenotypic performance, indicating complex inheritance of tolerance. Biochemical profiling revealed that tolerant landraces maintained higher chlorophyll and antioxidant enzyme activities and secreted greater quantities of organic acids (citrate and malate), facilitating Al exclusion through rhizosphere chelation. Gene expression analysis revealed the upregulation of <i>OsSTAR1</i>, <i>OsSTAR2</i>, and <i>OsFRDL4</i> in tolerant genotypes, promoting Al exclusion, whereas sensitive lines showed increased <i>OsNRAT1</i> and <i>OsALS1</i> expression, indicating a reliance on less effective internal detoxification pathways. These findings demonstrate that aluminium tolerance in traditional rice landraces from Northeast India is driven primarily by exclusion mechanisms. The identified tolerant genotype represents a valuable genetic resource for the breeding of acid soil-resilient rice cultivars, offering promising prospects for sustainable rice production and food security in Al-affected regions.</p>

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Exclusion versus detoxification: contrasting molecular strategies of aluminium tolerance in rice landraces of Northeast India

  • 期刊论文

  • 发表日期：

    2026年4月2日

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  • Darshana Sharma,
  • Sudipta Sankar Bora,
  • Rahul Chandrakant Kaldate,
  • Ishani Borthakur,
  • Pradip Chandra Dey,
  • Madhumita Barooah

摘要

Key message

Rice genotypes differ in aluminium tolerance, with resistant landraces sustaining root growth OsSTAR1 / OsSTAR2 mediated exclusion, organic acid efflux, and antioxidant defense, whereas sensitive varieties accumulate Al³⁺ via OsNRAT1–OsALS1 mediated internal sequestration, leading to oxidative damage.

Abstract

This study reveals two contrasting molecular strategies of aluminium (Al) tolerance root-based exclusion and internal detoxification among indigenous rice landraces of Northeast India, a region severely affected by acidic soil-related Al toxicity. Fifty-three rice genotypes were evaluated under hydroponic Al stress (200 μM AlCl₃) through integrated morphophysiological, biochemical, and gene expression analyses. Tolerant genotypes such as Ahom Sali and Disang sustained root growth, biomass, and relative water content, whereas sensitive types such as Ranjit Sub-1 and Jolkonwari showed severe root inhibition and oxidative damage. SSR marker analysis of 33 polymorphic loci (mean PIC = 0.48) confirmed high genetic diversity, but weak correlation with phenotypic performance, indicating complex inheritance of tolerance. Biochemical profiling revealed that tolerant landraces maintained higher chlorophyll and antioxidant enzyme activities and secreted greater quantities of organic acids (citrate and malate), facilitating Al exclusion through rhizosphere chelation. Gene expression analysis revealed the upregulation of OsSTAR1, OsSTAR2, and OsFRDL4 in tolerant genotypes, promoting Al exclusion, whereas sensitive lines showed increased OsNRAT1 and OsALS1 expression, indicating a reliance on less effective internal detoxification pathways. These findings demonstrate that aluminium tolerance in traditional rice landraces from Northeast India is driven primarily by exclusion mechanisms. The identified tolerant genotype represents a valuable genetic resource for the breeding of acid soil-resilient rice cultivars, offering promising prospects for sustainable rice production and food security in Al-affected regions.