Plant & Animal Genomes XIV Conference

January 14-18, 2006
Town & Country Convention Center
San Diego, CA

Establishment Of Stress And Defense Related EST Landmarks In The Soybean (Glycine max L.) Physical Map.

Kay M Shopinski¹ , Jeffry L Shultz¹ , Javed Iqbal^1,2 , Dheepakkumaran Jayaraman¹ , David Lightfoot¹

¹  Genomics Core Facility, Southern Illinois University, IL, USA

²  VBI, VA

³  USDA Peoria, IL

Genome analysis of soybean (Glycine max L.) has been complicated by its paleo-auto-polyploid nature and conserved homeologous regions. Landmarks of expressed sequence tags (ESTs) located within a minimum tile path (MTP) of contiguous (contig) bacterial artificial chromosome (BAC) clones can identify stress and defense related gene rich regions in the genome. A physical map derived MTPs of 8,064 BAC clones encompassed the soybean genome. The ESTs used included 143 from a root library selected by subtractive hybridization from a multiply disease resistant soybean cultivar ‘Forrest’ 14 days after inoculation with Fusarium solani f. sp. glycines (F. virguliforme). Another 166 were chosen from a root EST library (Gm-r1021) from soybean cultivar ‘Williams 82’. The EST pools located 613 paralogs for 201 of the 309 probes used (range 1-13 per functional probe). Ninety BAC clones contained more than one kind of paralog. Many more BACs (259) contained a single paralog of one of the 201 probes detectable gene families. ESTs were anchored on soybean linkage groups A1, B1, C2, E, D1a+Q, G, I, M, H, and O. When compared to Arabidopsis thaliana there were more 2 and 4 member paralog families reflecting the diploidized-tetraploid nature of the soybean genome. However there were fewer families with 5 or more genes and the same number of single genes suggesting massively extensive selective gene loss or rapidly divergent evolution to regenerate the unique genes in some families.