GENOME ANALYSIS OF THINOPYRUM-INTERMEDIUM AND THINOPYRUM-PONTICUM USING GENOMIC IN-SITU HYBRIDIZATION

Genomic in situ hybridization (GISH) using genomic DNA probes from Thi nopyrum elongatum (Host) D.R. Dewey (genome E, 2n = 14), Thinopyrum be ssarabicum (Savul. & Rayss) A. Love (genome J, 2n = 14), and Pseudoroe gneria strigosa (M. Bieb.) A. Love (genome S, 2n = 14), was used to ex amine the genomic constitution of Thinopyrum intermedium (Host) Barkwo rth Sr D.R. Dewey (2n = 6x = 42) and Thinopyrum ponticllm (Podp.) Bark worth Sr D.R. Dewey (2n = 10x = 70). Evidence from GISH indicated that hexaploid Tit, intermedium contained the J, J(s), and S genomes, in w hich the J genome was related to the E genome of Th. elongatum and the J genome of Th. bessarabicum. The S genome was homologous to the S ge nome of Ps. strigosa, while the J(s) genome referred to modified J- or E-type chromosomes distinguished by the presence of S genome specific sequences close to the centromere. Decaploid Th. ponticum had only th e two basic genomes J and J(s). The J(s) genome present in Th. interme dium and Th. ponticum was homologous with E or J genomes, but was quit e distinct at centromeric regions, which can strongly hybridize with t he S genome DNA probe. Based on GISH results, the genomic formula of T h. intermedium was redesignated JJ(s)S and that of Th. ponticllm was r edesignated JJJJ(s)J(s). The finding of a close relationship among S, J, and J(s) genomes provides valuable markers for molecular cytogeneti c analyses using S genome DNA probes to monitor the transfer of useful traits from Th. intermedium and Th. ponticum to wheat.