DIFFERENTIATION OF TALL FESCUE MONOSOMIC LINES USING RFLP MARKERS ANDDOUBLE MONOSOMIC ANALYSIS

Tall fescue (Festuca arundinacea Schreb., 2n =6x =42) is a major cool- season pasture and turf grass with the genome constitution PPG(1)G(1)G (2)G(2). Lack of aneuploid stocks hinders genetic studies in this impo rtant grass. The objective of this study was to characterize 23 fertil e, embryo culture-derived, 'Kenwell' tall fescue monosomic lines by me ans of (i) RFLP markers, (ii) double monosomic analysis, and (iii) iso zyme phenotypes of Fl progeny. Standard procedures were used for RFLP chemiluminescent detection, crossing, cytogenetic analyses, and obtain ing isozyme banding patterns. Using RFLP markers, we ascertained that four monosomic lines were hemizygous for a P-genome marker and the 23 plants were placed into 17 groups based on plants having the same RFLP handing patterns. For double monosomic analysis,metaphase I chromosom e pairing relationships were ascertained for 220 F-1 progeny from 26 c rosses among the monosomic lines. Five of the progeny were trisomic, 1 48 disomic, 60 monosomic, and seven had 40 chromosomes. All of the 40- chromosome progeny were double monosomic plants, indicating the monoso mes carried in the parents were not the same chromosome. Isozyme pheno types were ascertained for 203 F-1 progeny from crosses for double mon osomic analysis which had both 42-and 41-chromosome progeny to determi ne if an isozyme locus mapped to the monosome from the female parent. A PGI-2 locus most likely mapped to one monosome. Double monosomic ana lysis provided evidence that at least four of the 21 possible tall fes cue monosomic lines were obtained.