variable between FLO͞LFY-like proteins. The proline-rich domain is not well pronounced in NLY and PrFLL. The acidic domain of gymnosperm FLO͞LFY-like proteins is not as strong as corresponding domains of angiosperm homologs. Because the proline-rich and acidic domains are located within the variable regions, they may be subject to evolutionary changes." Also, we would like to point out that in Fig. 1, the first 44 amino acids of the PEAFLO sequence were missing. A corrected figure and its legend appear below.FIG. 1. Sequence comparison of FLO͞LFY-like proteins (accession numbers in parentheses): PrFLL from P. radiata (U92008); NLY from P. radiata (U76757); BOFH from Brassica oleracea (718362); LFY from Arabidopsis thaliana (M91208); NFL1 and NFL2 from Nicotiana tabacum (U16172) and U16174, respectively); PEAFLO from Pisum sativum (AF010190); FLO from Antirrhinum majus (M55525); PtFL from Populus balsamifera (U931 96); and RFL from Oryza sativa (AB005620). Black boxes indicate identical amino acids, shaded boxes indicate amino acids with similar properties, and dots indicate gaps introduced to optimize alignment. c1 anc c2, conserved regions; v1 and v2, variable regions. Positions of the proline residues within the proline-rich region are indicated by asterisks. Acidic domain indicated by dashed line. 5336Correction Proc. Natl. Acad. Sci. USA 96 (1999) ABSTRACTThe LEAFY͞FLORICAULA genes from Arabidopsis and Antirrhinum are necessary for normal f lower development and play a key role in diverse angiosperm species. A homologue of these f lower meristem-identity genes, NEEDLY (NLY), has been identified in Pinus radiata. Although the NLY protein shares extensive sequence similarity with its angiosperm counterparts, it is lacking the proline-rich and acidic motifs thought to function as transcriptional activation domains. NLY already is expressed during vegetative development at least 5 years before the transition to the reproductive phase. Expression of NLY in transgenic Arabidopsis promotes f loral fate, demonstrating that, despite its sequence divergence, NLY encodes a functional ortholog of the FLORICAULA͞LEAFY genes of angiosperms. Expression of the LFY::NLY transgene can largely complement the defects in f lower development caused by a severe lfy allele.

Three MADS-box genes isolated from Monterey pine (Pinus radiata), PrMADS1, PrMADS2, and PrMADS3, are orthologs to members of the AGL2 and AGL6 gene subfamilies in Arabidopsis. These genes were expressed during early stages of pine shoot development in differentiating seed-and pollen-cone buds. Their transcripts were found within a group of cells that formed ovuliferous scale and microsporophyll primordia. Expression of PrMADS3 was also detected in a group of cells giving rise to needle primordia within differentiated vegetative buds, and in needle primordia.

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Two cDNA clones encoding endo-␤-1,4-glucanases (EGases) were isolated from a radiata pine (Pinus radiata) cDNA library prepared from immature female strobili. The cDNAs PrCel1 (P ᠪ inus r ᠪadiata cellulase 1 ᠪ ) and PrCel2 encode proteins 509 and 515 amino acids in length, respectively, including putative signal peptides. Both proteins contain domains conserved in plant and bacterial EGases. The proteins PRCEL1 and PRCEL2 showed strong similarity to each other (76% amino acid identity), and higher similarity to TPP18 (73 and 67%, respectively), an EGase cloned from tomato (Lycopersicon esculentum) pistils, than to any other reported EGases. Northern-blot analyses indicated that both genes displayed a similar pattern of expression. The only significant difference was in the level of expression. In situ hybridizations were used to demonstrate that, within differentiating pine reproductive structures, PrCel1 expression was greatest in microsporangia in pollen strobili and near the developing ovule in the seed strobili. Expression was also found in vegetative tissues, especially in regions experiencing cell elongation, such as the elongating region of root tips. Both proteins have an ability to degrade carboxymethylcellulose in vitro. Genomic-blot analysis indicated the presence of a family of EGase genes in the radiata pine genome, and that PrCel1 and PrCel2 are transcribed from distinct one-copy genes.

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