Cytogenetic analyses of tall fescue (Festuca arundinacea Schreb.) plants regenerated from tissue cultures

The primary objective of this study was to compare the cytogenetic variability present in tall fescue (Festuca arundinacea Schreb.) plants regenerated from embryo-derived calli of ethylmethane sulfonate (EMS)-treated (TEM) and non-EMS treated (REG) caryopses and from control plants grown from seed. Secondary objectives were to relate meiotic abnormalities with chiasma frequency, pollen stainability, phenotypic characteristics, and chromosome numbers.

Panicles of tall fescue were collected in May of 1982 and 1983 and fixed in Carnoy's solution. The anthers were dissected from the florets, placed on a microscope slide, and the contents pressed out. After staining with 0.5% acetocarmine, the pollen mother cells were scored for chromosome number, chiasmata frequency, and meiotic aberrations. Pollen from mature anthers was placed on a microscope slide, stained with Newton's Iodine Solution, and examined for viability. Phenotypic characteristics such as date of maturity, growth habit, and leaf morphology of plants exhibiting abnormalities were noted.

All control plants had 2n=42 chromosomes and no meiotic abnormalities were observed. Nearly 48% of the regenerated plants derived from EMS-treated embryos, and nearly 42% of the plants derived from nontreated embryos exhibited aberrations, the most common being lagging chromosomes, chromosomal bridges, and micronuclei in spores. A low frequency of aneuploids, one monosomic (2n=41), and two trisomics (2n=43) were identified. Univalents associated with the aneuploids were responsible for lagging chromosomes and micronuclei in those plants. Inversion heterozygosity and "sticky" chromosome associations accounted for chromosomal bridges.

Meiotic analyses should be performed on all plants re generated from tissue cultures to aid in the identification of novel genotypes. Meiotically aberrant plants have the potential for possible use in genetic and/or breeding studies.