Genetic dissection of vegetative propagation traits in Eucalyptus tereticornis and E-globulus

We have detected quantitative trait loci (QTLs) affecting vegetative propag ation traits in Eucalyptus tereticornis and Eucalyptus globulus. Using ampl ified fragment length polymorphism (AFLP) genetic linkage maps, the inherit ance of 199 markers was assessed in 94 F-1 individuals with extreme adventi tious rooting response, and in 221 randomly chosen F-1 individuals. Phenoty pes were scored in 1995 and 1996. QTL analyses were performed using chi-squ are tests (chi(2)), single-marker analysis (SMA), interval mapping (IM) and composite interval mapping (CIM). All approaches yielded similar QTL detec tion results. Three QTLs are hypothesized for mortality (MORT=% dead cuttin gs), nine for adventitious rooting (ROOT, RCT=% rooted cuttings relative to the surviving or total cuttings, respectively), four for petrification (PE TR=% surviving unrooted cuttings), one for sprouting ability (SPR=number of stump sprout cuttings harvested in 1995) and four for the stability of adv entitious rooting (STAB=absolute value of the difference ROOT95-ROOT96). Al l putative QTLs for MORT and PETR were located on the E. tereticornis map, and for SPR and STAB on the E. globulus map. We found different QTLs for MO RT, ROOT, RCT, SPR and STAB. Putative QTLs accounted for 2.6-17.0% of the p henotypic variance of a trait (R-2). Estimated standardized gene substituti on effects varied between 0.13 and 0.49 phenotypic standard deviations (sig ma(p)). These re suits indicate that the phenotypic variation in these trai ts has a meaningful genetic component and that stable QTLs can be found in a family of reasonable size where no previous knowledge of the trait was av ailable.