Genetic diversity in bentgrass (Agrostis spp.) by AFLP analysis and studies on disease resistance to Typhula incarnata Lasch.

摘要

Bentgrasses (Agrostis spp.) (>220 species) are widely occurring temperate grasses with varied ploidy levels that represent a vast resource for genetic improvement of turfgrass cultivars. Genetic characterization would help in the selection of breeding materials and utilization of germplasm resources.{09}In the first part of this study, 40 plant introductions of 14 Agrostis species from 20 countries were studied using fluorescently labeled amplified fragment length polymorphism (AFLP) analyses. Data from 400 AFLP markers and using Unweighted Pair Group Method with Arithmetic Mean (UPGMA) showed genetic similarities between species ranged from 0.62 to 0.98. Principal component analysis (PCA) distinguished seven groups. Dendrogram constructed on the basis of genetic similarities defined groups consistent with the geographic origins and physical and genetic attributes of the species. In the second part of this study, AFLP analyses was performed on old and modern creeping and redtop bentgrasses, selected MSU lines, and plant introductions. Using 355 AFLP markers and clustering analyses, three groups were distinguished. The mean genetic similarity for creeping bentgrasses in the first group was 0.78. Creeping bentgrasses from the US were separated as a subgroup from the European plant introductions. Selected MSU lines were differentiated from modern cultivars. Redtop bentgrasses were found in different groups.; Bentgrasses are susceptible to devastating winter injury caused by gray snow mold (Typhula incarnata Lasch). In the third part of this study, 115 random amplified polymorphic DNA (RAPD) markers on 40 isolates of gray snow mold from Michigan, Wisconsin and Minnesota showed mean percentage polymorphism at 48%. Dendrograms constructed showed a wide genetic distance between isolates suggesting high variability and possibly recent colonization. The high variation within populations could be due to outcrossing and recombination. In the last part of the study, controlled screening procedures against T. incarnata were developed and used to search for a resistant genotype in creeping bentgrass populations and plant introductions of Agrostis . We selected 20 creeping bentgrass genotypes from 890 samples taken from old Northern Michigan golf courses and identified 3 accessions of colonial bentgrasses from 40 plant introductions with potentially useful resistance to T. incarnata.