Ball State University1
University of Toledo2
USDA-ARS-SPRRS3 (posthumously, 10/02)
Tripsacum SR5: Shatter Resistance study population --Blakey, CA1, Goldman, SL2, Dewald, CL3, Frutiger, K2 In a collaborative arrangement with Stephen Goldman (PSRC, University of Toledo), and Chet Dewald (USDA-ARS-SPRRS), preliminary steps have been made towards the development of a study in diploid Tripsacum dactyloides (2n=2x=36). The new population has been designated as the SR5 population. The population has been involved in a large-scale seed shattering and forage quality studies currently being conducted by the USDA-ARS-SPRRS, Woodward, OK (Chester Dewald, personal communication). Large tissue samplings of parental and F1, and a set of 240 out of 1250 SR5 F2 individuals, were harvested during the summers of 2000 and 2001. Samplings of tissue were collected from each F2 individual from the same field for two successive years to reduce possibility of sampling error. These F2 samplings provide both a back-up population tissue set for the BSU on-site map population, and a set of QTL materials scored for seed shattering studies and eventual molecular analysis. The tissue harvested from this subset of 240 individuals of the SR5 F2 has limitations as the actual mapping population. Additional tissue harvests were not possible with the commencing of seed shattering studies in summer 2002, which allowed for nursery contamination by shattered seed. The QTL study materials remain in storage while characterized markers are assembled using the Tripsacum SR5 F2 mapping nursery at Ball State University, Muncie, IN.

As of August 2001, DNA had been isolated and a set of 72 parental/F1 screening blots for the eight enzymes EcoRI, EcoRV, BamHI, BglII, DraI, SacI, XbaI, and HindIII had been constructed. Initial screening results of 5 of seven UMC maize bin markers revealed clearly mappable polymorphisms. These five markers include: umc31 (4-6 bands), umc38 (1 bright monomorphic band + 3-7 polymorphic bands), umc44 (4-6 bands), umc65 (4-8 bands), umc66 (4-8 bands). While Tripsacum typically has a more complex band pattern than that seen in maize, previous experience with Tripsacum mapping has shown that inter-specific probes reduce data complexity. Addition of other markers, particularly Tripsacum genomic markers (TDA), and cDNAs, will be added as they become available through collaborative efforts. The advantage of these materials is that they have the same parentage as the F2 mapping population being established at Ball State University, Muncie, IN, and represent one of the first molecular QTL sample sets extensively scored/rated for analysis of seed shattering and forage quality in Tripsacum.

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