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Buffalograss genetic linkage mapping, chinch bug resistance characteristics and turfgrass performance
Buffalograss (Buchloe dactyloides (Nutt.) Engelm.) is a warm season perennial grass that has emerged as a turfgrass species due to its low maintenance requirements, and suitability for different turf uses. Turfgrass quality and western chinch bug (Blissus occiduus Barber) resistance are of interest to buffalograss breeding programs. The objectives of the current research were to (1) explore genetic variability for chinch bug resistance among available genotypes; (2) assess the merits of hybridization breeding in creating chinch bug resistance, buffalograss morphological traits, and turfgrass performance genetic variability; and (3) construct a genetic linkage map of diploid buffalograss. Fifteen buffalograss genotypes comprising diploids, tetraploids, pentaploid and hexaploids were evaluated for chinch bug resistance. Three half-sib populations were generated by crossing four diploid buffalograss genotypes (three females and one male). Random samples of the half- sibs were field evaluated for turfgrass performance. One full-sib population was selected, and 94 progeny from this population were evaluated for chinch bug resistance and genotyped using Sequence Related Amplified Polymorphisms (SRAP) and Simple Sequence Repeat (SSR) markers for genetic linkage mapping. The evaluation of parents and progeny indicated highly significant differences among the crosses and the parents for all the traits studied. The progeny nested within crosses differed only for genetic color and turfgrass quality in fall. Best linear unbiased prediction (BLUP) showed high improvement potential for lateral spread, genetic color, and spring density. These results support the potential of recombination breeding in identifying transgressive segregants for certain traits of interest in buffalograss genotypes. The genotypes (diploids, tetraploids, pentaploid, and hexaploids) and the progeny evaluated for chinch bug resistance had highly significant differences for chinch bug damage ratings. The genotypes were categorized into moderately resistant to moderately susceptible types. Genotypes NE 3297, 196, 184, Bowie, and Legacy were moderately resistant with a damage rating of >1, but <3, while NE 2990, NE 2838, and 1-57-19 were moderately susceptible with a damage rating of≥3, but <4. The susceptible genotypes, NE 2990, NE 2838, and 378, had area under the chinch bug damage progress curve ranging from 88.2 to 78.1, while the resistant genotypes, Prestige, NE 3297 and NE 196, had values of 53.7 to 59.2. There was no relationship between ploidy level of the genotypes and chinch bug resistance. The progeny were segregated into one highly resistant, 78 progeny (83%) moderately resistant, 13 (14%) moderately susceptible, and two highly susceptible types. This response is a strong indication that chinch bug resistance can be improved by hybridization. Morphological traits such as leaf and stolon internodes length were highly variable, indicating a strong potential of slow growth and reduced mowing in buffalograss, but had no impact on chinch bug resistance of the progeny evaluated. The co-segregation analysis of the marker data placed 42 markers into nine discrete linkage groups covering 355.10 cM, with linkage group sizes ranging from 10 cM to 119.78 cM. A range of 2 to 18 loci per linkage group were mapped with an average map distance between two consecutive markers of 12.68 cM. This linkage group would be a rational starting point for further delineation of the buffalograss linkage map with more markers, and could serve as an anchor for genome sequencing. Results from this study lay a foundation for a new direction for buffalograss breeding research that will aid further study and improvement of turfgrass quality and pest resistance. ^
Agriculture, Agronomy|Agriculture, Horticulture
Serba, Desalegn Debelo, "Buffalograss genetic linkage mapping, chinch bug resistance characteristics and turfgrass performance" (2009). ETD collection for University of Nebraska - Lincoln. AAI3386559.