Plant & Animal Genome IX Conference Plant & Animal Genome IX Conference
Poster: Sequencing & EST
P01_71.html
A soybean [Glycine max (L.) Merrill] consortium has undertaken the task of large-scale gene discovery in soybean, using expressed sequence tags (ESTs) to discover new soybean genes. As part of this project, five directional complementary DNA (cDNA) libraries were constructed from soybean seedling root, mature root, nodule, 24-hour infected seedling root, and degenerating cotyledon messenger RNAs (mRNAs), resulting in 25,132 ESTs. The ESTs from each library were assembled into 16,960 within-library contigs. These were assembled across all five libraries into 14,016 among-library contigs, which were assigned protein identifications, if possible. No known protein similarities were found for 4,766 of the among-library contigs; another 3,636 protein descriptions contained no functional information. The infected seedling root has six abundant pathogen infection- or defense-related proteins, totaling 2.34% of the ESTs. Despite being grown in the dark, photosynthesis-related transcripts comprise at least 2.65% of the total degenerating cotyledon mRNA, while abundant glyoxysomal proteins explain another 3.61%. The nodule library has devoted 15.2% of its transcript population to nodulins, including leghemoglobins and four novel transcripts. Isoforms of ADR12-2 and metallothionein differed in their relative abundances across the five tissues. The EST sequences and corresponding cDNA clones are publicly available for functional studies. By the time the soybean EST project ends in March 2002, at least 200,000 soybean EST sequences will have been deposited into dbEST, providing abundant material for functional studies. This study, as a part of the soybean EST project, has contributed significantly to soybean gene discovery and genomics.