Breeding Strategies for Durable Powdery Mildew Resistance in Wheat

Key Takeaways

1. Powdery Mildew Resistance in Wheat: Wheat-Dasypyrum villosum translocation lines carrying Pm55 gene variants offer significant resistance to powdery mildew.
2. Developmental-Stage Specific Resistance: Pm55a (previously known as Pm55) provides stage and tissue-specific resistance, while Pm55b (formerly Pm5V) offers resistance across all developmental stages.
3. Allelic Relationship of Resistance Genes: Pm55a and Pm55b are allelic, encoding CNL proteins that confer broad-spectrum resistance to powdery mildew.
4. Interaction with Inhibitor Gene SuPm55: The two alleles interact differently with SuPm55, influencing wheat resistance level.
5. Inactivation of SuPm55 Reduces Plant Fitness: Disabling SuPm55 negatively affects the overall plant health.
6. Potential Breeding Strategy: Combining SuPm55/Pm55a and Pm55b in wheat breeding does not lead to allele suppression or yield reduction, suggesting a viable strategy for durable resistance.

Breeding Strategies for Durable Powdery Mildew Resistance in Wheat: Insights from Lu et al., 2024

Background

Powdery mildew is a widespread and destructive disease affecting wheat crops globally. In response, Lu et al. (2024) have conducted research to develop more effective and durable strategies for disease control.

Study Focus

The study centers on two translocation lines of wheat carrying different genes for powdery mildew resistance:

• T5AL·5V#4S and T5DL·5V#4S lines, carrying the Pm55 gene, exhibit developmental-stage and tissue-specific resistance.
• T5DL·5V#5S line, carrying the Pm5V gene, confers resistance at all plant developmental stages.

Key Findings

• Cloning and Renaming of Genes: The researchers successfully cloned Pm55 and Pm5V, revealing they are allelic. Consequently,

they are renamed Pm55a and Pm55b, respectively.

• Function of Pm55 Alleles: Both alleles encode coiled-coil, nucleotide-binding site-leucine-rich repeat (CNL) proteins, effectively providing broad-spectrum resistance to wheat powdery mildew.
• Different Interactions with SuPm55: Pm55a and Pm55b show distinct interactions with the linked inhibitor gene SuPm55, which affects their resistance capabilities against wheat powdery mildew.
• Impact of SuPm55 Inactivation: Inactivating SuPm55, although it enhances resistance, decreases overall plant fitness.
• Breeding Implications: Combining SuPm55/Pm55a and Pm55b in wheat does not cause allele suppression or decrease yield. This finding opens new avenues for breeding wheat with durable resistance to powdery mildew without compromising crop yield.

Implications for Wheat Breeding

The study by Lu et al. (2024) offers valuable insights into genetic resistance mechanisms against powdery mildew in wheat. It underscores the importance of understanding allelic relationships and gene interactions for developing effective breeding strategies. The findings suggest a promising approach to enhance wheat resistance to powdery mildew while maintaining plant health and yield, which is crucial for global food security.

Read the complete study here.