Skip to main content
ARS Home » Pacific West Area » Corvallis, Oregon » Forage Seed and Cereal Research Unit » Research » Publications at this Location » Publication #130559
Title: INHERITANCE OF SUPEROXIDE DISMUTASE (SOD-1) IN A PERENNIAL X ANNUAL RYEGRASS CROSS AND ITS ALLELIC DISTRIBUTION AMONG CULTIVARS

Author
item WARNKE, SCOTT - OSU CROP & SOIL SCIENCE
item Barker, Reed
item BRILMAN, LEAH - SEED RESEARCH OF OREGON
item YOUNG, WILLIAM - OSU CROP & SOIL SCIENCE
item COOK, RONALD - OSU CROP & SOIL SCIENCE

Submitted to: Theoretical and Applied Genetics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/7/2002
Publication Date: 10/3/2002
Citation: WARNKE, S.E., BARKER, R.E., BRILMAN, L.A., YOUNG, W.C., COOK, R.L. INHERITANCE OF SUPEROXIDE DISMUTASE (SOD-1) IN A PERENNIAL X ANNUAL RYEGRASS CROSS AND ITS ALLELIC DISTRIBUTION AMONG CULTIVARS. THEORETICAL AND APPLIED GENETICS. 2002. v. 105. p. 1146-1150.

Interpretive Summary: Perennial ryegrass and Italian, or annual ryegrass are two of the most widely cultivated grasses used for turf and forage throughout the world. Approximately 90 percent of the worldwide supply of certified seed of perennial and Italian ryegrass is produced in Oregon's Willamette Valley. The close genetic similarity of the two species is of concern to seed certification agencies because genetic or physical contamination of turf type perennial ryegrass by forage-type annual ryegrass is objectionable for high quality turf use. The primary test utilized is seedling root fluorescence (SRF). The search for alternative tests for SRF has not been successful in over 70 years. A superoxide dismutase locus (Sod) has shown frequency differences between perennial and annual types, but its inheritance and relationship to annuality traits needed to be determined. We found that Sod-1 has two alleles, Sod-1a and Sod-1b, that segregate as a single gene. A survey of 13 annual and 24 perennial ryegrass cultivars showed that Sod-1bb was present in 98% of the perennial ryegrass plants tested, was very low in annual ryegrass cultivars from Asia and Europe, but up to 56% in annual ryegrasses from the Western Hemisphere. The potential of the Sod-1 locus to serve as a test to separate the two growth types will depend on the source of the annual-type contamination, and may not work well at all if contamination if from Gulf annual ryegrass.

Technical Abstract: Identifying annual ryegrass contamination in perennial ryegrass seed lots has been of major interest in seed testing laboratories and for seed regulatory agencies for many years. This study was conducted to characterize a superoxide dismutase locus (Sod-1) and determine its potential to distinguish cultivated ryegrass species. The inheritance of (Sod-1) was evaluated in a three generation annual X perennial ryegrass mapping population and the molecular form of the Sod-1 locus was determined by H2O2 and KCN inhibitor assays. The common alleles at the Sod-1 locus were scored in 13 annual and 24 perennial ryegrass cultivars to determine the potential of this locus for species separation. Segregation of the Sod-1 locus fit the expected segregation ratio for a single locus with two alleles. Inhibitor assays indicated that the Sod-1 and Sod-2 loci were both Cu/ZnSod enzymes. The Sod-1b allele was homozygous in 98% of perennial ryegrass individuals from 24 cultivars indicating that this allele is a good indicator of perenniality. All eight annual ryegrass cultivars originating in Europe or Asia had a low frequency of Sod-1b homozygous individuals, but the five cultivars originating in the Western Hemisphere had genotype frequencies for homozygous Sod-1b up to 56%. The potential of the Sod-1 locus to serve as a test to separate the two growth forms depends on the source of the annual-type contamination.