No abstract

Knowledge of genetic diversity, population structure, and degree of linkage disequilibrium (LD) in target association mapping populations is of great importance and is a prerequisite for LD-based mapping. In the present study, 96 genotypes comprising 92 accessions of the US peanut minicore collection, a component line of the tetraploid variety Florunner, diploid progenitors A. duranensis (AA) and A. ipae¨nsis (BB), and synthetic amphidiploid accession TxAG-6 were investigated with 392 simple sequence repeat (SSR) marker bands amplified using 32 highly-polymorphic SSR primer pairs. Both distance-and model-based (Bayesian) cluster analysis revealed the presence of structured diversity. In general, the wild-species accessions and the synthetic amphidiploid grouped separately from most minicore accessions except for COC155, and were eliminated from most subsequent analyses. UPGMA analysis divided the population into four subgroups, two major subgroups representing subspecies fastigiata and hypogaea, a third group containing individuals from each subspecies or possibly of mixed ancestry, and a fourth group, either consisting of COC155 alone if wild species were excluded, or of COC155, the diploid species, and the synthetic amphidiploid. Modelbased clustering identified four subgroups-one each for fastigiata and hypogaea subspecies, a third consisting of individuals of both subspecies or of mixed ancestry predominantly from Africa or Asia, and a fourth group, consisting of individuals predominantly of var fastigiata, peruviana, and aequatoriana accessions from South America, including COC155. Analysis of molecular variance (AMOVA) revealed statistically-significant (P \ 0.0001) genetic variance of 16.87% among subgroups. A total of 4.85% of SSR marker pairs revealed significant LD (at r 2 C 0.1). Of the syntenic marker pairs separated by distances \ 10 cM, 11-20 cM, 21-50 cM, and [ 50 cM, 19.33, 5.19, 6.25 and 5.29% of marker pairs were found in strong LD (P B 0.01), in accord with LD extending to great distances in self pollinated crops. A threshold value of r 2 [ 0.035 was found to distinguish mean r 2 values of linkage distance groups statistically from the mean r 2 values of unlinked markers; LD was found to extend to 10 cM over the entire minicore collection by this criterion. However, there were large differences in r 2 values among marker pairs even among tightly-linked markers. The implications of these findings with regard to the possibility of using Vikas Belamkar-This work was performed in partial fulfillment of the requirements for the Master of Science degree.

‘Tamrun OL11’ (Reg. No. CV‐118, PI 665017) is a high‐yielding, high‐oleic, runner‐type peanut (Arachis hypogaea L. subsp. hypogaea var. hypogaea) cultivar that has resistance to Sclerotinia minor Jaggar) and improved grade attributes over previously released runner‐type cultivars that are resistant to S. minor. It was tested under the experimental designation Tx055308 and released by Texas AgriLife Research at College Station, TX on 21 July 2011. Tamrun OL11 was derived from a single cross between Tx977116 F2:8, which has a high oleic‐oil content and resistance to Tomato spotted wilt virus, and the cultivar Tamrun 98, which has a normal oleic‐oil content and a high percentage of total sound mature kernels (TSMKs). Early selections were practiced using the pedigree selection technique. Initial yield testing began in the F3:5 generation in 2006 and continued through 2009 for a total of 25 multiple location trials. Tamrun OL11 performed equally as well as Tamrun OL07, which is resistant to S. minor, and was superior to the widely grown Flavorunner 458 cultivar for yield and disease resistance under high incidence of S. minor. Tamrun OL11 also performed equally as well as Flavor Runner 458 and was superior to Tamrun OL07 for the percentage of TSMKs. The objective of releasing this line is to provide growers with a cultivar that will yield and grade the same as the currently grown Flavor Runner 458 cultivar while reducing grower risk by maintaining the level of resistance to S. minor that the recently released Tamrun OL07 cultivar provides.

Tamrun OL07' (Reg. no. CV-92, PI-642851) is a runner market-type peanut (Arachis hypogaea L. subsp. hypogaea var. hypogaea) cultivar with a high O/L ratio and good yield poten-