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United States Department of Agriculture

Agricultural Research Service

Title: Analysis of Bromus Inermis Populations Using Amplified Fragment Length Polymorphism Markers to Identity Duplicate Accessions

Authors
item Bradley, Vicki
item Kisha, Theodore

Submitted to: Meeting Proceedings
Publication Type: Proceedings
Publication Acceptance Date: April 1, 2005
Publication Date: July 1, 2005
Citation: Bradley, V.L., Kisha, T.J. 2005. Analysis of bromus inermis populations using amplified fragment length polymorphism markers to identity duplicate accessions. In: Molecular breeding for the improvement of forage crops and turf: Proceedings of the 4th International Symposium on the Molecular Breeding of Forage and Turf, a satelllite workshop of the XXth International Grasslands Congress, July 2005, Aberystwyth, Wales. p. 267.

Interpretive Summary: The temperate grass germplasm collection maintained at the USDA, ARS Western Regional Plant Introduction Station (WRPIS) in Pullman, Washington, consists of more than 18,000 accessions. Passport and collection data suggest that some of these accessions are duplicates, and their maintenance drains limited resources. The objective of this study was to use Amplified Fragment Length Polymorphism (AFLP) marker analysis on four populations of smooth bromegrass, Bromus inermis Leyss. subsp. inermis 'Manchar´, a cross-pollinated perennial grass, to determine if the genetic variation among them was significant. If not, then maintaining separate populations would be unnecessary. Total nucleic acids were extracted from new-leaf tissue of 24 plants from each population. Restriction enzyme digestion, ligation of adapter sequences, preliminary amplification, and selective amplification was performed using AFLP kits. Two primer pairs were analyzed providing a total of 780 polymorphic markers whose polymorphic information content (PIC) values were calculated, as was the proportion of genetic diversity that resides among populations (GST). Using the average of the PIC values obtained at each locus for each population as variances within populations, and the proportion of the total variance calculated using GST as variance among populations, an F-test (3 and 92df for among and within population variances, respectively) revealed no significant differences among populations. (F = 0.35). The results indicate that the four populations are very similar and it is not necessary to maintain them separately.

Technical Abstract: The maintenance of duplicate accessions drains limited resources. Four populations of smooth bromegrass, Bromus inermis Leyss. subsp. inermis 'Manchar', were characterized using AFLP marker analysis to determine if the genetic variation among them was significant. If not, then maintaining separate populations would be unnecessary. Two primer pairs were analyzed providing a total of 780 polymorphic markers. Identification of markers was performed automatically and exported to a spreadsheet where allele frequencies and variances were calculated. PIC values, measures of genetic variance within populations, were calculated over all plants analyzed (total variance) and for each of the populations. The proportion of genetic diversity that resides among populations (GST) was calculated using two methods. The Nei method gave a value of 0.068 and the Hamrick and Godt method gave a value of 0.071. Using the average of the PIC values obtained at each locus for each population as variances within populations, and the GST value as variance among populations, an F-test (3 and 92df for among and within population variances, respectively) revealed no significant differences among populations (F= 0.35). The results indicate that the four populations are very similar and it is not necessary to maintain them separately.

Last Modified: 8/22/2014
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