Meiotic analyses of tall fescue somaclones

Abstract

Genetic studies of open-pollinated, hexaploid tall fescue (Festuca arundinacea Schreb., 2n = 6x = 42) would be enhanced by having aneuploids in a homogeneous background. Regeneration of plants from tissue culture was one possible method of obtaining aneuploids. 'Kenwell' tall fescue was developed from S2 and S3 clones and thus should be more homogeneous than many tall fescue varieties. The somaclones were derived from calli of in vitro cultured mature embryos. Meiotic analyses of 15 parental clones showed mostly ring bivalent pairing and 76.2–98.2% pollen stainability. Of the 166 somaclones analyzed meiotically, there were 99 euploids, 59 aneuploids (2n = 38, 39, 40, and 41), and 8 of higher ploidy (2n = 56, 70, 78, and 80). The somaclones were grouped according to chromosome number (ranging from 38 to 42), meiotic behavior (0–2 vs. 3 or more multivalents), and pollen stainability (more or less than 20%). Also observed were anaphase bridges, heteromorphic bivalents, and centric fragments. The meiotic changes were best explained by the hypothesis that there was perturbation in the replication of heterochromatic regions during tissue culture. Breakage and possible rejoining most likely involved chromosome arms with heterochromatic regions, which resulted in translocations, deficiencies, deletions, and telosomes.Key words: Festuca arundinacea, aneuploids, tissue culture, somaclonal variation.