GENES ENCODING 11S-GLOBULIN-LIKE PROTEINS ARE EXPRESSED IN THE MEGAGAMETOPHYTE SOON AFTER FERTILIZATION IN EASTERN WHITE-PINE (PINUS-STROBUS L)

The nucleotide sequence of two cDNA clones synthesized from eastern wh ite pine (Pinus strobus L.) ovule mRNA showed significant sequence hom ology to the legumins, which correspond to the 11S-globulins of severa l angiosperms. Northern hybridizations with one of the cDNA clones, na med Gib-2 (P. strobus 11S-globulin-like clone 2), revealed that the mR NA was present in the ovules from the early globular stage of embryoge nesis through the mature seed stage but not in unfertilized ovules. Gi b mRNA was found in the megagametophyte of ovules containing late-stag e globular embryos by filter-bound RNA and tissue print hybridization experiments. No Gib mRNA was found in in vitro-cultured globular stage embryos with attached suspensors, sporophytic ovule tissues, whole se edlings, or mature needles.