Plant & Animal Genome V Conference
Town & Country Hotel, San Diego, CA, January 12-16, 1997.
PAG-V: W37 - QTL MAPPING IN A HALF-SIB FAMILY OF LOBLOLLY PINE
W37
QTL MAPPING IN A HALF-SIB FAMILY OF LOBLOLLY PINE
O'MALLEY, DAVID M.(1), Jorge Vasquez(1), Barbara S. Crane(2), David L. Remington(1), Shamima Akhter(1), John J. MacKay(1), Rongling Wu(1), Ben-Hui Liu(1), Steven E. McKeand(1), Ronald R. Sederoff(1)
1. Department of Forestry, North Carolina State University, Raleigh, NC 27695-8008
2. International Paper Co., Route 1, Box 421, Bainbridge, GA 31717
Two ways that QTL mapping in forest trees differ from QTL mapping in crop plants are that individual trees are planted further apart in the field and that measurements are taken on individuals for several years. Our mapping population is a highly variable half-sib family. RAPD marker genotypes were determined for megagametophytes (haploid tissue from seed with same genotype as maternal gamete) corresponding to each tree in the field. The trees were planted in 10 plots each containing 100 trees, with 21 x 31 spacing. We have found strong environmental covariance (spatial autocorrelation) in some plots obscures QTL effects. Position variables (e.g., rows and columns) explain as much as 25% of variation in shoot elongation in some plots. Marker:trait associations using residuals from these regressions have higher significance levels than marker:trait associations using raw phenotypic measurement data. The QTL effects in half-sib families are average effects and are detectable in some years but not in others. An experiment was carried out to determine whether linkages could be detected for RAPD markers scored only in megagametophytes. The initial results look promising and could make it possible to use older half-sib family block plantings for retrospective QTL studies.