Characterization of euploid backcross progenies derived from interspecifichybrids between Oryza sativa and O-eichingeri by restriction fragment length polymorphism (RFLP) analysis and genomic in situ hybridization (GISH)

Restriction fragment length polymorphism (RFLP) analysis and GISH (genomic in situ hybridization) were performed on euploid plants derived from crosse s between Oryza sativa (2n = 24, AA) and two brown planthopper-resistant ac cessions of O. eichingeri (2n = 24, CC). After screening with 164 RFLP mark ers, 60 of the 67 euploid plants were identified as introgression lines, ea ch carrying 1-6 small O. eichingeri segments integrated on chromosomes 1, 2 , 6, or 10. In the somatic chromosome preparations of F-1 hybrid, O. eichin geri chromosomes, fluorescing greenish-yellow in the sequential GISH, appea red to be longer and to contain more heterochromatin than O. sativa ones, a nd this karyotypic polymorphism can be used to detect some introgressed O. eichingeri segments in euploid plants. In addition, GISH identification pre sented direct evidence for the transfer of small segments from O. eichinger i to O. sativa chromosome(s) which were subsequently recognized according t o their condensation pattern, arm ratio, and chromosome length. The present results would contribute to the molecular mapping and selection of O. eich ingeri - derived brown planthopper-resistant gene and positive yield QTLs.