Molecular cytogenetic analysis of genomes between Festuca mairei and Lolium perenne

Intergeneric hybridization has occurred between species of Lolium and Festuca. It has been demonstrated, through morphological and conventional cytogenetic analyses of intergeneric hybrids between Lolium and Festuca, that the genomes of the two genera are closely related. However, information is lacking on how close the genomes are related between the two genera. High frequency of chromosome pairing between Lolium and Festuca was extensively documented in the literature, but the interpretations sometimes were contradictory. The objectives of this study were to: (1) apply in situ hybridization technique to understand chromosome pairing behavior of hybrids between Lolium perenne and Festuca mairei , (2) evaluate the application of molecular markers---species-specific repetitive DNA sequences to the introgression of alien chromatin transfer and (3) understand the genomic relationships between the two tetraploid Festuca species---F. mairei and F. arundinacea var. glaucescens.; Our results indicated that meiocytes of Lolium-Festuca are amenable to genomic in situ hybridization (GISH) analyses. The mean frequency of bivalents was 7.19 in the triploid hybrid (LM1M2) between F. mairei (M1M1M2M 2) and L. perenne (LL). GISH revealed that 53% of the bivalents in the hybrids were chromosome associations involving one chromosome of L. perenne and one of F. mairei. Nearly 50% of the univalents were actually chromosomes of F. mairei. The earlier assumption that chromosomes from the same species paired preferentially must be revised. This study agrees with a few other recent studies that chromosomes of Lolium and Festuca may be genetically equivalent and reciprocal mixing of the genomes may be possible.; Two repetitive DNA sequences were characterized from a tall fescue ( F. arundinacea) genomic library. TF521 was a F. pratensis (PP) species-specific probe as it showed no hybridization signals with diploid Lolium. TF436 was specific to tetraploid Festuca, such as F. arundinacea var. glaucescens and F. mairei. TF436 was useful to monitor the chromatin introgression of F. mairei in the progenies of the hybrid between F. mairei and L. perenne. Potential addition and translocation lines were identified in the BC 1F1 derivatives of F. mairei x L. perenne. The sequences of TF436 and TF521 were submitted to GeneBank with accession number as AF087933 and AF087934, respectively.; An amphiploid of F. mairei and L. perenne was synthesized, which had a frequency of chromosome configurations of 9.85 I + 15.42 II + 0.43 III + 0.10 IV at metaphase I. The amphiploid was unstable cytologically and had 21% pollen KI stainability. A hybrid between F. arundinacea (6x) and F. mairei (4x) was produced with mean chromosome configurations of 6.47 I + 13.40 II + 0.30 III + 0.19 IV + 0.01 V. This hybrid and the amphiploid may be useful in the improvement of drought persistence of tall fescue. GISH failed to differentiate the tetraploid Festuca which suggests that F. arundinacea var. glaucescens and F. mairei have similar genomic structures.; Physical mapping of repetitive DNA sequences onto chromosomes may provide landmarks for karyotypic analyses. pTA71 from wheat (Triticum aestivum L.) rDNA was located on one pair of chromosomes of F. pratensis and two pairs of chromosomes of F. arundinacea by in situ hybridization.