Genetic Mechanism of Flag Leaf Size in Foxtail Millet Revealed

Strategic Insights -

Research from Shanxi Agricultural University in China has shed light on the genetic mechanism underlying flag leaf size in foxtail millet (Setaria italica L.). The study found that flag leaf size significantly influences final grain yield in crops, including foxtail millet, and optimizing flag leaf size is considered an effective strategy for enhancing grain yield potential under higher planting densities. The researchers identified 11 flag leaf width (FLW) QTLs on chromosomes 3, 5, and 6, explaining 2.35%-36.06% of the variation in FLW. Among these, qFLW5-2 was a major QTL, detected consistently across 3 environments and explaining a large proportion of FLW variation.

Key Takeaways:

  • The flag leaf significantly influences final grain yield in foxtail millet, and optimizing flag leaf size is crucial for enhancing grain yield potential under higher planting densities.
  • The study identified 11 flag leaf width (FLW) QTLs on chromosomes 3, 5, and 6, explaining 2.35%-36.06% of the variation in FLW.
  • qFLW5-2 was a major QTL, detected consistently across 3 environments and explaining a large proportion of FLW variation.
  • RNA-seq revealed 2,293 and 2,338 differentially expressed genes (DEGs) between biparents at heading stage and grain filling stage, respectively.
  • 11 and 9 DEGs within the location range of qFLW5-2 were identified among 2 comparison groups (HZG-H_vs_CN35-H and HZG-G_vs_CN35-G).
  • Combining QTL mapping and RNA-seq, the researchers speculated that Seita.5g134600 (encoding an auxin responsive protein Aux/IAA) and Seita.5G123900 (encoding a cytochrome P450 family protein) as key candidate genes for qFLW5-2.
  • Variation analysis confirmed that the lines or germplasm with Seita.5G134600 allele, both within the RIL population and natural populations, exhibited significantly wider leaves than those with Seita.5G134600 allele.

Statistics:

  • 11 flag leaf width (FLW) QTLs were identified on chromosomes 3, 5, and 6, explaining 2.35%-36.06% of the variation in FLW.
  • 2,293 and 2,338 differentially expressed genes (DEGs) were identified between biparents at heading stage and grain filling stage, respectively.
  • 11 and 9 DEGs within the location range of qFLW5-2 were identified among 2 comparison groups (HZG-H_vs_CN35-H and HZG-G_vs_CN35-G).
  • The QTL qFLW5-2 explained a large proportion of FLW variation, with an effect size of 2.35%-36.06%.

Sources:

  • Combining QTL mapping and RNA-Seq reveals candidate genes controlling flag leaf width in foxtail millet. BMC Plant Biology, 2025;25(1):1365.