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<p>Bread wheat is the second most important cereal globally, fulfilling 20% of human daily calorie and protein intake. Among biotic stresses, leaf rust, caused by <i>Puccinia triticina</i>, reduces crop yields by 20–25% globally. Breeding for genetic disease resistance is the most effective and economical strategy to minimise these losses. However, the dynamic nature of the pathogen renders many of the deployed genes ineffective in a short span, prompting the search for novel seedling/all stage and adult plant resistance (APR) genes. Identifying and mapping novel disease resistance genes requires parents with contrasting phenotypes. The mapping of seedling/all stage resistance is well standardised through bi-parental mapping populations. However, mapping APR genes is challenging due to the need for precise phenotyping and the presence of additional minor genes in commonly used susceptible parents. In the present study, a subset of 20 leaf rust susceptible landraces was selected from a panel of 4575 bread wheat landraces used in the mission mode gene discovery program. These 20 susceptible lines along with checks, HI1500 as a resistant line and Agra Local (AL) a susceptible control, were evaluated at the seedling and the adult plant stage for two consecutive seasons. Fourteen of 20 lines showed an extremely susceptible seedling response (IT-3 to 33+) against all of the tested sixteen different pathotypes of the leaf rust pathogen. Field evaluation under timely and late sown conditions for two years characterised these susceptible lines with higher final disease severity (60–100&#xa0;S), a very high AUDPC score (560–1330), and a high ACI value (75–100). The chances of duplicity among these accessions were eliminated by comparing the SNP data as per the homozygous genotyping difference based on identity by state on the G-DIRT Software, indicating unique identity of each accession. The super-susceptible lines identified through this study could be effectively used as contrasting susceptible parents, a basic requirement in mapping the component traits of APR genes. Additionally, these can also efficiently serve as rust spreader lines in the disease screening nursery.</p>

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Identification and Characterisation of Super Susceptible Bread Wheat (Triticum aestivum L.) Landraces against Leaf Rust Pathogen (Puccinia triticina Eriks.)

  • 期刊论文

  • 发表日期：

    2026年6月18日

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  • Naman Raj,
  • Ujjwal Kapoor,
  • Ramesh Bhurta,
  • Vrinda Batra,
  • Subhash Bijarania,
  • Niharika Mallick,
  • M. G. Mallikarjuna,
  • Vaibhav Kumar Singh,
  • Atul Kumar,
  • Om Prakash Gangwar,
  • Pramod Prasad,
  • Subhash Chander Bhardwaj,
  • Sundeep Kumar,
  • Gyanendra Pratap Singh,
  • Amit Kumar Singh,
  • Shailendra Kumar Jha

摘要

Bread wheat is the second most important cereal globally, fulfilling 20% of human daily calorie and protein intake. Among biotic stresses, leaf rust, caused by Puccinia triticina, reduces crop yields by 20–25% globally. Breeding for genetic disease resistance is the most effective and economical strategy to minimise these losses. However, the dynamic nature of the pathogen renders many of the deployed genes ineffective in a short span, prompting the search for novel seedling/all stage and adult plant resistance (APR) genes. Identifying and mapping novel disease resistance genes requires parents with contrasting phenotypes. The mapping of seedling/all stage resistance is well standardised through bi-parental mapping populations. However, mapping APR genes is challenging due to the need for precise phenotyping and the presence of additional minor genes in commonly used susceptible parents. In the present study, a subset of 20 leaf rust susceptible landraces was selected from a panel of 4575 bread wheat landraces used in the mission mode gene discovery program. These 20 susceptible lines along with checks, HI1500 as a resistant line and Agra Local (AL) a susceptible control, were evaluated at the seedling and the adult plant stage for two consecutive seasons. Fourteen of 20 lines showed an extremely susceptible seedling response (IT-3 to 33+) against all of the tested sixteen different pathotypes of the leaf rust pathogen. Field evaluation under timely and late sown conditions for two years characterised these susceptible lines with higher final disease severity (60–100 S), a very high AUDPC score (560–1330), and a high ACI value (75–100). The chances of duplicity among these accessions were eliminated by comparing the SNP data as per the homozygous genotyping difference based on identity by state on the G-DIRT Software, indicating unique identity of each accession. The super-susceptible lines identified through this study could be effectively used as contrasting susceptible parents, a basic requirement in mapping the component traits of APR genes. Additionally, these can also efficiently serve as rust spreader lines in the disease screening nursery.