Resistance of Diploid Triticeae Species and Accessions to the Columbia Root-knot Nematode, Meloidogyne chitwoodi.

The Columbia root-knot nematode, Meloidogyne chitwoodi race 2, is associated with several plant species, including members of the tribe Triticeae. We evaluated 15 diploid species for M. chitwoodi gall and reproductive indices from the following genera: Agropyron, Pseudoroegneria, Hordeum, Psathyrostachys, and Thinopyrum. Species from the genus Thinopyrum (Thinopyrum bessarabicum; J genome) and Psathyrostachys (Psathyrostachys fragilis, P. juncea, P. stoloniformis; N genome) expressed more resistance to M. chitwoodi than species within the genera Agropyron (Agropyron cristatum and A. mongolicum; P genome), Pseudoroegneria (Pseudoroegneria spicata, P. stipifolia, A. aegilopoicles, P. libanotica; S genome), and Hordeum (Hordeum bogdanii, H. brevisubulatum, H. californicum, and H. chilensis; H genome), although there was variation among individuals within P. spicata, P. juncea, and P. fragilis. The variation among genera and within species indicates that it would be possible to select Triticeae grasses for resistance to M. chitwoodi in order to identify and introgress genes for resistance into cultivated cereals.