Introduction
Rough bluegrass (Poa trivialis) is a cool-season
perennial grass that is grown in wet shaded locations for home lawns, golf
courses and sports fields. It is also used for winter overseeding of warm
season turfgrasses in south where it forms one of the highest quality turf of
any cool-season turfgrasses. Colonial bentgrass (Agrostis capillaris) is
a sod-forming, cool-season perennial grass, primarily grown in northeastern and
northwestern regions of the United States. This fine textured grass spreads by
short rhizomes and stolons to form close tight turf and is best suited to golf
course fairways. Velvet bentgrass (Agrostis canina), the finest textured
of all bentgrasses, is adapted to cool, moist areas of coastal regions of the United States. It is primarily used on putting greens, where it forms an attractive,
low-growing, compact turf with a high-quality putting surface. It is also the
most shade-tolerant of all the bentgrasses and is used on fairways where
nitrogen levels are kept low. All of these three species are not extensively
utilized, partly due to the lack of breeding efforts. Germplasm of turfgrass
species, including the aforementioned three species, are being collected by
USDA plant introduction stations throughout the world. However, these germplasm
are largely uncharacterized genetically. To better utilize these collections, genetically
characterizing each accession of these species is critically important.
Molecular markers are a powerful, reliable and cost effective tool for
evaluating genetic diversity and can provide important insights for breeding.
The objectives of this research were to: (1) evaluate the genetic diversity of
selected accessions and varieties of rough bluegrass, colonial bentgrass and
velvet bentgrass using RAPD(Randomly Amplified Polymorphic DNA) markers, and
(2) evaluate the morphological variations of these materials under field
conditions.
Materials and methods
This research involves 61 accessions, including 27 accessions of rough bluegrass, 27 accessions of colonial bentgrass, and 7 accessions of velvet bentgrass that were obtained from the Western Regional Plant Introduction Station (USDA) at Pullman, WA. All seeds were sown in cell packs and DNA was extracted from young leaves after growing one-month in the greenhouse. After the seedlings reached a desirable height, they were transplanted to the Iowa State Horticulture Research Farm for further studies on morphological characteristics under field conditions. All accessions were planted in a randomized complete block design with a maximum of 18 replications for each accession.
RAPD analysis is based on the polymerase chain reaction (PCR). After DNA extraction, PCR conditions were optimized for RAPD primers by examining at least four accessions. Eighty primers were screened for polymorphism. Fifteen out of 80 primers that showed high polymorphism were used to analyze the 27 accessions of rough bluegrass.
The PCR products were checked by agarose gel
electrophoresis. The polymorphic bands were scored either as “1” for presence
and “0” for absence and a similarity coefficient matrix was formed. This matrix
was analyzed by the “Mesquite” software to construct dendrogram and principal
coordinate analysis. Using this similarity coefficient matrix, genetic distance
was analyzed by the “PAUP” software.
Results
Dendrogram analysis showed that accessions in three out of five clusters in the dendrogram tree have a positive relationship with their geographic origins. This is confirmed by their genetic distances. Genetic distances showed that accessions from the United States and Iraq have high genetic distance between them. Accessions from Denmark and Yugoslavia have low genetic distance between them. Data on morphological characteristics of these accessions is unavailable at present.
For colonial and velvet bentgrasses, DNA was extracted and
PCR was optimized. Primers were screened and 18 out of 80 primers that were
screened showed high polymorphism. Data on genetic distance and morphological
characteristics of these accessions is unavailable at present.
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ISU Turfgrass:2004 Turfgrass Report | College of Agriculture |
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