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Background <p>Rice blast, caused by <i>Magnaporthe oryzae</i>, remains a&#xa0;major global threat to rice production. This study integrated agronomic evaluations, pathogenicity screening (local blast races), and molecular identification of key resistance&#xa0;(R) genes to support breeding strategies suited to Egyptian conditions.</p> Methods <p>Twenty-seven rice genotypes were assessed for yield-related traits, field resistance, and R&#xa0;genes presence using marker-assisted analysis. Analysis of variance estimated genetic variability, broad-sense heritability (h<sup>2</sup>bs%), and expected genetic progress. Pathogenicity tests employed 18 local isolates representing five races (IH, ID, IC, IE, and&#xa0;II). Molecular characterization involved PCR-based amplification of R‑gene-linked markers, sequencing, and phylogenetic analysis.</p> Results <p>Genotypes exhibited significant variability across all traits. Days to maturity, grain yield plant<sup>−1</sup>, and grain yield (t&#xa0;feddan<sup>−1</sup>; 1&#xa0;feddan = 4200 m<sup>2</sup>) exhibited high h<sup>2</sup>bs and the greatest expected genetic advance, indicating strong potential for phenotypic selection. Pathogenicity screening revealed that Sakha 101 and Sakha 104 had lost resistance, while Giza 183, Giza 177, and Egyptian Yasmine maintained full resistance. Race ID was the most virulent (42%). Testing with Japanese differential varieties showed that <i>Pi-ks, Pi‑z, Pi‑i,</i> and <i>Pi‑k</i> all worked. Molecular analyses confirmed DNA markers associated with <i>Pi‑i</i> and <i>Pi‑k</i>, and identified the predominant <i>Pi‑9</i> in line GZ6296-12-1-2-1‑1. Sequencing confirmed <i>Pi‑9</i> encodes an <i>Oryza sativa</i> Japonica <i>PIK6-NP</i>-like resistance protein on chromosome&#xa0;6. Phylogenetic analysis demonstrated genetic divergence between highly resistant lines Giza 177 and Giza 183.</p> Conclusions <p>This study identified superior rice genotypes combining high yield potential with broad-spectrum resistance to <i>M.&#xa0;oryzae</i> and validated R‑gene markers, offering efficient tools for gene pyramiding and marker-assisted selection.</p>

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Integrated Agro-Pathological and Molecular Assessment of Selected Local and Introduced Rice Genotypes for Blast Resistance Under Field and Controlled Conditions in Egypt

  • 期刊论文

  • 发表日期：

    2026年6月26日

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  • Abdel-Hamid A. Ali,
  • Rokia Abd-elkader,
  • Moamen M. Abou El-Enin,
  • Walaa M. Essa,
  • Atef M. Mohamed,
  • Ahmed Shaaban,
  • Amir El-Keredy

摘要

Background

Rice blast, caused by Magnaporthe oryzae, remains a major global threat to rice production. This study integrated agronomic evaluations, pathogenicity screening (local blast races), and molecular identification of key resistance (R) genes to support breeding strategies suited to Egyptian conditions.

Methods

Twenty-seven rice genotypes were assessed for yield-related traits, field resistance, and R genes presence using marker-assisted analysis. Analysis of variance estimated genetic variability, broad-sense heritability (h2bs%), and expected genetic progress. Pathogenicity tests employed 18 local isolates representing five races (IH, ID, IC, IE, and II). Molecular characterization involved PCR-based amplification of R‑gene-linked markers, sequencing, and phylogenetic analysis.

Results

Genotypes exhibited significant variability across all traits. Days to maturity, grain yield plant−1, and grain yield (t feddan−1; 1 feddan = 4200 m2) exhibited high h2bs and the greatest expected genetic advance, indicating strong potential for phenotypic selection. Pathogenicity screening revealed that Sakha 101 and Sakha 104 had lost resistance, while Giza 183, Giza 177, and Egyptian Yasmine maintained full resistance. Race ID was the most virulent (42%). Testing with Japanese differential varieties showed that Pi-ks, Pi‑z, Pi‑i, and Pi‑k all worked. Molecular analyses confirmed DNA markers associated with Pi‑i and Pi‑k, and identified the predominant Pi‑9 in line GZ6296-12-1-2-1‑1. Sequencing confirmed Pi‑9 encodes an Oryza sativa Japonica PIK6-NP-like resistance protein on chromosome 6. Phylogenetic analysis demonstrated genetic divergence between highly resistant lines Giza 177 and Giza 183.

Conclusions

This study identified superior rice genotypes combining high yield potential with broad-spectrum resistance to M. oryzae and validated R‑gene markers, offering efficient tools for gene pyramiding and marker-assisted selection.