Plant & Animal Genome VI Conference

W41

COMPARATIVE ANALYSIS OF cDNA SEQUENCES FROM DIFFERENTIATING PINE XYLEM

1. Forest Biotechnology Group, Department of Forestry, North Carolina State University, Raleigh, NC 27695-8008
2. Computational Biology Center, University of Minnesota, Minneapolis, MN 55455-0312

Xylem is a highly specialized tissue that is likely to express a unique complement of genes, particularly in woody plants. Environmental and developmental stimuli influence secondary xylem differentiation, producing morphological and chemical changes in wood. To increase our understanding of wood formation, expressed sequence tags were obtained from immature xylem of loblolly pine (Pinus taeda L.). A total of 1093 single pass sequences were obtained from 5' ends of cDNAs made from normal and environmentally modified tissue (compression wood) from bent trees. Cluster analysis detected 106 groups of similar sequences, ranging in size from two to twenty sequences. A total of 359 sequences fell into these groups, while 734 sequences were unique. Comparison of the pine EST dataset to ESTs of rice and Arabidopsis showed that 34% of the pine sequences are similar to rice or Arabidopsis ESTs. About 55% of the pine EST sequences show similarity to previously described sequences in public databases. Some of the recognized genes encode factors involved in cell wall synthesis, intermediary metabolism and cellular regulation. Fifty genes encoding putative cell wall structural protein sequences were present and cDNAs encoding most of the known lignin biosynthetic pathway enzymes were found. There are a large number of regulatory proteins present. Sequencing and mapping genes expressed during wood formation provides a basis for identifying mechanisms of xylem growth and differentiation.