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United States Department of Agriculture

Agricultural Research Service

Title: Genomic Relationships among Ryegrass Species Reveal Diagnostic Structure at the Specific Gene Level

Authors
item Barker, Reed
item Brown, Rebecca - UNIV OF RHODE ISLAND
item Warnke, Scott

Submitted to: American Society of Agronomy Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: September 30, 2005
Publication Date: October 31, 2005
Citation: Barker, R.E., Brown, R.N., Warnke, S.E. 2005. Genomic relationships among ryegrass species reveal diagnostic structure at the specific gene level. American Society of Agronomy Abstracts. Paper No. XXXX.

Interpretive Summary: Of the eight ryegrass species found world wide, perennial and Italian (or annual in the US) ryegrasses have major economic importance as turf and forage in temperate areas, but the ryegrass known internationally as annual, L. rigidum Gaud., is a major weed and the self-pollinated L. temulentum L. is listed as a noxious weed in 43 U.S. states. Thus, ability to rapidly identify seed of these four species as physical mixtures or originating from pollination among them is a priority for seed testing labs. We have studied several genes that appear different among the species as they relate to published cereal grain DNA sequences. Our results indicate that DNA-based tests for based on differences in these genes can be developed to rapidly, inexpensively, and accurately detect contamination of one ryegrass species in seed lots of another.

Technical Abstract: Traditional taxonomic classification of the ryegrasses (<I>Lolium</I> sp.) lists eight species. Of these, perennial (<I>L. perenne</I> L.) and Italian (or annual) (<I>L. multiflorum</i> Lam.) ryegrasses have major economic importance as turf and forage in temperate areas of the world. The ryegrass known internationally as annual, <I>L. rigidum</i> Gaud., is a major weed, but can also be used as a forage. Likewise the self-pollinated <I>L. temulentum</i> L. is listed as a noxious weed in 43 U.S. states. Thus, ability to rapidly identify seed of these four species as physical mixtures or originating from pollination among them is a priority for seed testing labs. Generalized RAPD and AFLP marker analyses showed DNA band profiles that differed among the species, but often a distinctive band in bulked samples would not be present in all individuals of one species and the band could be found at a low frequency in other species. The vernalization gene (<I>vrn-1</I>) and genes for the isozymes <I>pgi-2</I> and <I>sod-1</I> were cloned from the four ryegrass species based on primers developed from published cereal grain DNA sequences. DNA sequences from the ryegrasses were highly conserved, but polymorphisms were present which appear to be useful for accurately predicting species identity. The results indicate that DNA-based tests for these gene polymorphisms can be further developed to rapidly, inexpensively, and accurately detect contamination of one ryegrass species in seed lots of another.

Last Modified: 7/28/2014
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