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<p>Two proton-dependent members of the nitrate/peptide transporter (NPT) family-glucosinolate transporter 1 (<i>GTR1</i>) and <i>GTR2</i>-modulate long-distance mobility of glucosinolates (GLSs) in Brassicas, key secondary metabolites involved in defense. This study analyzed mustard genotypes varying in GLS content, combining organ-specific GLS profiling with qRT-PCR-based assessment of <i>GTR1</i> and <i>GTR2</i> transporter expression. Total GLS in siliques increased from anthesis (11.17–24.91 µmol g⁻¹ DW) through 3 days after fertilization (DAF; 16.30–35.72 µmol g⁻¹ DW), peaking at 14 DAF (21.90–69.14 µmol g⁻¹ DW), suggesting the developing silique as a major hub of net GLS accumulation. Thereafter, GLS in silique walls declined at 21 DAF (17.63–42.69 µmol g⁻¹ DW) and 30 DAF (9.01–32.68 µmol g⁻¹ DW), while mature seeds accumulated 24.32–123.45 µmol g⁻¹ defatted meal, suggesting developmental re-partitioning from maternal tissues toward the developing seeds, which acts as a major sinks during seed filling and maturation. Although <i>GTR1</i> and <i>GTR2</i> expression increased at late stages, inconsistent relationships with GLS content indicate that transporters expression alone is not a quantitative predictor of GLS accumulation. Instead, GLS outcomes likely reflect integrated control of biosynthesis, side-chain modification, and multi-step transport. Genotype x developmental stage interactions strongly shaped both total and individual GLS profiles, with sinigrin predominating in leaves and gluconapin in seeds. These findings suggest breeding strategies to optimize defense allocation and seed meal quality by altering GLS partitioning between maternal tissues and seeds and motivate future work to resolve homolog-specific transporter contributions and quantify <i>UMAMIT</i>/<i>GTR</i> protein abundance, cell-type localization, and in vivo transport activity alongside <i>MYB28</i> and biosynthetic gene expression.</p>

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Developmental shifts in glucosinolate allocation and GTR1/GTR2 expression in mustard (Brassica juncea (L.) Czern.)

  • 期刊论文

  • 发表日期：

    2026年6月2日

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  • Heena Rani,
  • Sanjula Sharma,
  • Harjeevan Kaur,
  • Meenakshi Mittal,
  • Chhaya Atri,
  • Gurpreet Kaur,
  • Rimaljeet Kaur,
  • S. S. Banga

摘要

Two proton-dependent members of the nitrate/peptide transporter (NPT) family-glucosinolate transporter 1 (GTR1) and GTR2-modulate long-distance mobility of glucosinolates (GLSs) in Brassicas, key secondary metabolites involved in defense. This study analyzed mustard genotypes varying in GLS content, combining organ-specific GLS profiling with qRT-PCR-based assessment of GTR1 and GTR2 transporter expression. Total GLS in siliques increased from anthesis (11.17–24.91 µmol g⁻¹ DW) through 3 days after fertilization (DAF; 16.30–35.72 µmol g⁻¹ DW), peaking at 14 DAF (21.90–69.14 µmol g⁻¹ DW), suggesting the developing silique as a major hub of net GLS accumulation. Thereafter, GLS in silique walls declined at 21 DAF (17.63–42.69 µmol g⁻¹ DW) and 30 DAF (9.01–32.68 µmol g⁻¹ DW), while mature seeds accumulated 24.32–123.45 µmol g⁻¹ defatted meal, suggesting developmental re-partitioning from maternal tissues toward the developing seeds, which acts as a major sinks during seed filling and maturation. Although GTR1 and GTR2 expression increased at late stages, inconsistent relationships with GLS content indicate that transporters expression alone is not a quantitative predictor of GLS accumulation. Instead, GLS outcomes likely reflect integrated control of biosynthesis, side-chain modification, and multi-step transport. Genotype x developmental stage interactions strongly shaped both total and individual GLS profiles, with sinigrin predominating in leaves and gluconapin in seeds. These findings suggest breeding strategies to optimize defense allocation and seed meal quality by altering GLS partitioning between maternal tissues and seeds and motivate future work to resolve homolog-specific transporter contributions and quantify UMAMIT/GTR protein abundance, cell-type localization, and in vivo transport activity alongside MYB28 and biosynthetic gene expression.