Resistance evaluation of wheat germplasm containing <i><scp>D</scp>n4</i> or <i><scp>D</scp>ny</i> against <scp>R</scp>ussian wheat aphid biotype <scp>RWASA</scp>3

Abstract

Abstract Host plant resistance can effectively manage R ussian wheat aphid ( D iuraphis noxia ) K urdjumov ( H omoptera: A phididae) in areas where it is an economically important pest of wheat. However, biotypes of D . noxia virulent on wheat containing resistance gene D n4 have been reported in both the U nited S tates and S outh A frica. Thirty wheat genotypes, including susceptible Y uma, resistant CI tr2401, as well as 25 genotypes containing D n4 and three genotypes containing D ny were planted under greenhouse conditions in B ethlehem, S outh A frica, and screened with D . noxia biotype RWASA 3. RWASA 3 caused susceptible damage symptoms in MTRWA 92‐145, A nkor, H alt, B ond CL , 18 FAWWON ‐ SA 262, P rowers99, 18 FAWWON ‐ SA 264, H atcher, Y umar, C orwa and T hunder CL all reported to contain the D n4 resistance gene. Genotypes PI 586956, S tanton and 18 FAWWON ‐ SA 257, containing the D ny‐ resistance gene were susceptible to RWASA 3. Similarly, coinciding development of virulence to resistance genes D n4 and D ny was reported in the U nited S tates. However, in this study, 13 D n4‐ containing genotypes showed moderate resistance when screened with RWASA 3 alluding to a more complex biotype‐gene‐interaction. These findings could indicate that D n4 and D ny may be related and possibly share a similar or common resistance factor. Further studies will be aimed at explaining these results investigating the possibility of an allelic cluster or series for D n4, possibly including D ny .