Field Evaluation of Emmer Wheat-Derived Synthetic Hexaploid Wheat for Resistance to Russian Wheat Aphid (Homoptera: Aphididae)

Abstract

Broadening the genetic base for resistance to Russian wheat aphid, Diuraphis noxia (Mordvilko) (Homoptera: Aphididae), in bread wheat, Triticum aestivum L., is desirable. To date, identified Russian wheat aphid resistance genes are either located to the D chromosomes or to rye translocation of wheat, and resistance derived from the A or B genomes of tetraploid Triticum spp. would therefore be highly beneficial. Fifty-eight synthetic hexaploid wheat, derived from interspecific crosses of Triticum dicoccum Schrank. and Aegilops tauschii (Coss.) Schmal. and their parents were evaluated for resistance to Russian wheat aphid under field conditions. Plots infested with aphids were compared with plots protected with insecticides. The T. dicoccum parents were highly resistant to Russian wheat aphids, whereas the Ae. tauschii parents were susceptible. Resistance levels observed in the synthetic hexaploids were slightly below the levels of their T. dicoccum parents when a visual damage scale was used, but no major resistance suppression was observed among the synthetics. Russian wheat aphid infestation on average reduced plant height and kernel weight at harvest in the synthetic hexaploids and the T. dicoccum parents by 3–4%, whereas the susceptible control ‘Seri M82′ suffered losses of above 20%. Because resistance in the synthetic hexaploid wheat is derived from their T. dicoccum parent, resistance gene(s) must be located on the A and/or B genomes. They must therefore be different from previously identified Russian wheat aphid resistance genes, which have all been located on the D genome of wheat or on translocated segments.

Aegilops tauschii, Diuraphis noxia, resistance evaluation, synthetic hexaploid wheat, Triticum dicoccum