1992. Enhanced meiotic chromosome pairing in intergeneric hybrids between Triticum aestivum and diploid Inner Mongolian Agropyron. Genome, 35: 98-102. Triticum aestivum cv. Chinese Spring (2n = 6x = 42, ABD genomes) was crossed with diploid Inner Mongolian Agropyron Gaertn. species A. cristatum and A. mongolicum and reciprocal hybrids between them (2n = 2x = 14, P genome, with or without B chromosomes). Intergeneric hybrids with 2n = 27, 28, 32, and 33 chromosomes were produced by the aid of embryo rescue. The extra chromosomes in two hybrids were assumed to be B chromosomes transmitted by the male Agropyron parent. Average meiotic pairing in the euploid hybrid with 28 chromosomes was 14.38 univalents + 4.92 bivalents + 1.26 trivalents. This level of pairing higher than expected was likely due to homeologous associations between wheat chromosomes. This data indicates that the P genome of diploid as well as tetraploid Agropyron originating from Inner Mongolia possess a genetic system interfering with 5B homoeologous restricting system of wheat.Key words: intergeneric hybrids, Triticum aestivum, diploid Agropyron species, chromosome pairing. CHEN, Q., JAHIER, J., et CAUDERON, Y. 1992. Enhanced meiotic chromosome pairing in intergeneric hybrids between Triticum aestivum and diploid Inner Mongolian Agropyron. Genome, 35 : 98-102. Triticum aestivum cv. Chinese Spring (2n = 6x = 42, genomes ABD) a ete croisi avec des espkces diploides du genre Agropyron Gaertn. originaires de Mongolie Interieure A. cristatum et A. mongolicum et des hybrides reciproques entre ces derniers (2n = 2x = 14, genome P, avec ou sans chromosomes B). Des hybrides intergeneriques a 2n = 27, 28, 32 et 33 chromosomes ont ete obtenus grace a la culture d'embryons. Les chromosomes surnumeraires dans deux hybrides etaient vraisemblablement des chromosomes B transmis par les parents males Agropyron. Le comportement meiotique moyen dans l'hybride euploi'de a 28 chromosomes Ctait : 14,38 univalents + 4,92 bivalents + 1,26 trivalents. Ce niveau d'appariement, plus ClevC que celui attendu, est vraisemblablement dQ a des associations homeologues entre les chromosomes de ble. Ce resultat indique que le genome P des Agropyron diploi'des comme celui des Agropyron tetraploi'des originaires de Mongolie Interieure posskde un ou des gkne(s) inhibant l'activite du systkme genetique contrdlant les appariements chromosomiques chez le blC.