Mechanisms of resistance of new wheat gene Dn10 in comparison with other Dn genes resistant to Russian wheat aphid.

The Russian wheat aphid (RWA, Diuraphis noxia Kurdjumov) is a global pest of wheat (Triticum aestivum L.) that became a significant problem to wheat and barley (Hordeum vulgare L.) in the United States soon after it was detected in 1986. Russian wheat aphid‐resistant wheat varieties expressing the Dn4 gene were effective in managing the first biotype, RWA1, from 1995–2003 until a new biotype, RWA2, overcame this resistance in 2003. Currently, only three genes are useful in developing RWA2 resistance in wheat. A new gene, Dn10, was recently discovered that is resistant to RWA2. This study characterized the effects that RWA1 and RWA2 had on the damage (leaf chlorosis and leaf roll) and growth components (plant height and leaf number) of plants expressing RWA resistance genes Dn4, Dn7, Dn10, Dn2401, Dn626580, and Dn2414 and the susceptible 'Yuma' 22 d after infestation. All plant genotypes that were RWA resistant expressed strong resistance to leaf chlorosis and leaf roll after RWA1 feeding. Results were similar for RWA2 except for the Dn4 genotype, which was equally susceptible as Yuma. Plant height was reduced by 50% for susceptible Yuma and Dn626580 by RWA1 and RWA2 feeding. Plant height and leaf reduction from RWA2 feeding on the susceptible Dn4 genotype were also reduced by 50%, whereas Dn7, Dn10, and Dn2414 reductions were <23%. Dn10 exhibited strong resistance to RWA1 and RWA2 feeding damage comparable with Dn7 and Dn2414 and showed less reduction in plant height than Dn2401 and Dn626580, which makes it a potentially valuable gene for wheat breeding programs. [ABSTRACT FROM AUTHOR]