EFFECTS OF MEGAGAMETOPHYTE REMOVAL ON DNA YIELD AND EARLY SEEDLING GROWTH IN COASTAL DOUGLAS-FIR

Stratified seeds of coastal Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco var, menziesii) were germinated, sown in soil, and seed coats and megagametophytes were removed at various stages of early seedling development. Yield and quality of DNA extracted from the megagametophy tes were related to several morphological trails of the seedlings afte r 2 months of growth in a controlled environment chamber. Regression a nd analysis of variance demonstrated nonlinear associations between st age of megagamelophyte removal and seedling size traits, DNA yield and quality, and RNA presence. Megagametophyte removal when cotyledons ha d extended one-quarter of their length (about 4 mm) outside the seed c oat (our stage 4) resulted in sufficient DNA for construction of satur ated PCR-(polymerase chain reaction) based genome maps and had little effect on seedling development.