1. National Center for Supercomputing Applications, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA
2. Pacific Northwest National Laboratory, Richland, Washington, USA, and was with the Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA
3. Department of Computer Science, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA
4. Department of Plant Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA