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<p>Rice blast, caused by <i>Magnaporthe oryzae</i>, poses a major threat to global rice production due to its potential to cause severe yield losses. Developing cultivars with durable resistance via strategic pyramiding of resistance (<i>R</i>) genes is essential for sustainable disease management. This study aimed to develop elite rice germplasms with effective <i>R</i> gene combinations and evaluate their resistance stability across multiple blast hotspots in Southwest China. A total of 136 resistant lines were selected from crosses involving elite parental lines based on disease nursery evaluations conducted in Wanzhou and Enshi locations. Subsequent multilocation trails identified 20 lines with stable resistance in Meitan, a region characterized by distinct <i>M. oryzae</i> populations, indicating substantial geographical variation in pathogen virulence. These results highlight the importance of multilocation testing in breeding programs targeting durable resistance. Allele-specific markers for 14 major <i>R</i> genes were used to determine the genetic profiles of the resistant lines. Over 50% of lines carried <i>Pi5</i>, <i>Pi54</i>, <i>Pita</i>, or <i>Pia</i>, with most genotypes harbored 3-5 genes, reflecting the extensive application of <i>R</i> gene pyramiding in rice breeding efforts. Notably, lines that showed strong resistance in Meitan had similar <i>R</i> gene profiles to susceptible lines, suggesting that uncharacterized major-effect <i>R</i> genes may be responsible for the resistance. This finding emphasizes that the functional role and interactions of major-effect genes, rather than the total number of genes stacked, are critical in achieving durable resistance in breeding. Overall, this study provides a region-specific framework for evaluating blast resistance and offers valuable genetic resources for developing adapted and durable rice cultivars in Southwest China.</p>

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Challenges and insights into pyramided R genes for durable rice blast resistance in Southwest China

  • 期刊论文

  • 发表日期：

    2026年3月16日

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  • Junhua Liu,
  • Zhongya Cai,
  • Mei Yang,
  • Peng Liu,
  • Shufan Lei,
  • Zhiwen Lv,
  • Shiyan Huang,
  • Zhongxian Liu,
  • Zeinab A. Kalboush,
  • Yan-yan Huang,
  • Chengzhi Huang

摘要

Rice blast, caused by Magnaporthe oryzae, poses a major threat to global rice production due to its potential to cause severe yield losses. Developing cultivars with durable resistance via strategic pyramiding of resistance (R) genes is essential for sustainable disease management. This study aimed to develop elite rice germplasms with effective R gene combinations and evaluate their resistance stability across multiple blast hotspots in Southwest China. A total of 136 resistant lines were selected from crosses involving elite parental lines based on disease nursery evaluations conducted in Wanzhou and Enshi locations. Subsequent multilocation trails identified 20 lines with stable resistance in Meitan, a region characterized by distinct M. oryzae populations, indicating substantial geographical variation in pathogen virulence. These results highlight the importance of multilocation testing in breeding programs targeting durable resistance. Allele-specific markers for 14 major R genes were used to determine the genetic profiles of the resistant lines. Over 50% of lines carried Pi5, Pi54, Pita, or Pia, with most genotypes harbored 3-5 genes, reflecting the extensive application of R gene pyramiding in rice breeding efforts. Notably, lines that showed strong resistance in Meitan had similar R gene profiles to susceptible lines, suggesting that uncharacterized major-effect R genes may be responsible for the resistance. This finding emphasizes that the functional role and interactions of major-effect genes, rather than the total number of genes stacked, are critical in achieving durable resistance in breeding. Overall, this study provides a region-specific framework for evaluating blast resistance and offers valuable genetic resources for developing adapted and durable rice cultivars in Southwest China.