Date of Award
Doctor of Philosophy
Forty-six inbreds related to Iowa Stiff Stalk Synthetic (BSSS) and Iowa Corn Borer Synthetic #1 (BSCB1) were assayed for polymorphism at 227 microsatellite loci. The inbreds consisted of progenitors of BSSS and BSCB1 as well as elite lines derived from those populations. Diversity statistics were used to estimate genetic variability among the derived lines, and to locate regions of the maize genome that have changed as a result of artificial selection. The four groups of germplasm were labeled CBP and SSP for the progenitors of BSCB1 and BSSS, respectively, and CBL and SSL for the lines derived from BSCB1 and BSSS, respectively.;There were means of 3.5 and 3.4 alleles per locus among the CBP and SSP, respectively, and 2.3 and 2.5 alleles per locus among the CBL and SSL. As expected, many more alleles were found in the progenitor groups than in the groups of derived lines. CBL showed only 60% of the alleles found in CBP, while SSL had 66% of the alleles found in SSP. Supporting previous studies in this area, we found that 26% of the alleles in SSP were unique to a single inbred. In CBP, 32% of the alleles were unique, a figure slightly higher than previous results in BSCB1 or BSSS. Of the unique alleles in both progenitor groups, 73% were not found in any of the derived lines. There were 33 marker loci in BSSS and 18 marker loci in BSCB1 that exhibited reductions in gene diversity that can be attributed to artificial selection (P = 0.1).;Genetic distance between the progenitor groups was very low, indicating the progenitors were not highly divergent from each other. Rogers's distance (RD) between progenitor groups and derived line groups was identical in both BSSS and BSCB1, suggesting that the derived lines are equally divergent from their respective progenitor groups. The largest RD was between the two derived-line groups, about 35% greater than the progenitor-to-derived line distance. Rogers's distance between individual derived lines ranged from 15 to 54 in SSL and 25 to 56 in CBL, indicating some of the derived lines are very closely related.
Digital Repository @ Iowa State University, http://lib.dr.iastate.edu
James R. Rouse
Rouse, James R., "Genetic diversity among progenitors and derived lines of two maize (Zea mays L.) populations " (2004). Retrospective Theses and Dissertations. 1195.