Terrance P. Riordan

Molecular characterization of Buffalograss germplasm using sequence-related amplified polymorphism markers

Buffalograss [Buchloe dactyloides (Nutt.) Englem] germplasm has a broad resource of genetic diversity that can be used for turfgrass, forage and conservation. Buffalograss is the only native grass that is presently used as a turfgrass in the Great Plains region of North America. Its low growth habit, drought tolerance and reduced requirement for fertilizer and pesticides contribute to interest in its use. The objectives of this study were to use sequence-related amplified polymorphism (SRAP) markers in the evaluation of genetic diversity and phenetic relationships in a diverse collection of 53 buffalograss germplasms, and to identify buffalograss ploidy levels using flow cytometry. Based on their DNA contents, buffalograss genotypes were grouped into four sets, corresponding to their ploidy levels. Thirty-four SRAP primer combinations were used. This is the first report of the detection of differentiating diploid, tetraploid, pentaploid and hexaploid buffalograss genotypes, representing diverse locations of origin, using SRAP markers. Cluster analysis by the unweighted pair-group method with arithmetic averages based on genetic similarity matrices indicated that there were eight clusters. The coefficients of genetic distance among the genotypes ranged from 0.33 up to 0.99 and averaged D=0.66. The genetic diversity estimate, He, averaged 0.35. These results demonstrated that genotypes with potential traits for turfgrass improvement could readily be distinguished, based on SRAP. The use of PCR-based technologies such as SRAP is an effective tool for estimating genetic diversity, identifying unique genotypes as new sources of alleles for enhancing turf characteristics, and for analyzing the evolutionary and historical development of cultivars at the genomic level in a buffalograss breeding program.

Evaluation of Buffalograss Germplasm for Resistance to Blissus occiduus (Hemiptera: Lygaeidae)

Abstract Blissus occiduus Barber has emerged as an important insect pest of buffalograss, Buchloë dactyloides (Nuttall) Engelmann, in Nebraska. This research evaluated selected buffalograss germplasm for resistance to B. occiduus. Eleven buffalograss selections were screened for chinch bug resistance in three greenhouse studies and two field evaluations. Based on chinch bug damage, NE91–118, ‘Tatanka’, ‘Bonnie Brae’, and ‘Cody’ were rated highly to moderately resistant. These four buffalograsses exhibited minimal damage, even though all were heavily infested with chinch bugs. NE84-45-3 and ‘378’ were highly susceptible to B. occiduus. Field evaluations confirmed chinch bug resistance ratings under field conditions. NE91–118 displayed high levels of resistance in the field screening evaluations, whereas Cody and Tatanka showed moderate levels of resistance, and 378 was highly susceptible.