FISH and RFLP Marker‐Assisted Introgression of Festuca mairei Chromosomes into Lolium perenne

Abstract

ABSTRACTPlant breeders and geneticists have attempted for several decades to combine perennial ryegrass (Lolium perenne L.) with fescue (Festuca spp.) to create novel forage grasses containing both high forage quality and good drought tolerance. Difficulty in selecting true hybrids with alien chromatin or chromosome addition–substitution has been a major barrier in Festuca × Lolium breeding programs. In this investigation, fluorescence in situ hybridization (FISH) and restriction fragment length polymorphism (RFLP) markers were used to monitor transfer of Festuca mairei St. Yves chromosomes into L. perenne through intergeneric hybrids. Among 64 hybrid plants of the BC1G1 generation (intercrossed progeny of first backcross to L. perenne), chromosome addition and substitution of F. mairei were identified by FISH using total genomic DNA of F. mairei as a probe. Forty‐two clones from a Pst I‐genomic DNA library of F. arundinacea Schreb. were used to screen for the presence of F. mairei DNA in the hybrid plants. These RFLP probes rapidly identified presence of the F. mairei genome in F1, F2, BC1, but not in BC2 plants. In contrast, genomic FISH on meiotic cells effectively detected any F. mairei chromosomes as well as chromosomal pairing relationships in any hybrid. By monitoring and selectively introducing F. mairei chromosomes into ryegrass, these molecular markers may accelerate the Festuca × Lolium breeding for improvement of ryegrass.