PAG-VI: GENERATION AND CHARACTERIZATION OF EXPRESSED SEQUENCE TAGS (ESTs) OF THE MODEL LEGUME (Lotus japonicus)

PAG-VI  Plant & Animal Genome VI Conference

Town & Country Hotel, San Diego, CA, January 18-22, 1998.

W87

GENERATION AND CHARACTERIZATION OF EXPRESSED SEQUENCE TAGS (ESTs) OF THE MODEL LEGUME (Lotus japonicus)

KRZYSZTOF SZCZYGLOWSKI1, Philipp Kapranov1 2, Beth Kasiborski1, Frans J. De Bruijn1 2 3

  1. MSU-DOE Plant Research Laboratory, Michigan State University, East Lansing, MI USA 48824
  2. Department of Microbiology, Michigan State University, East Lansing, MI USA 48824
  3. Genetic Program, Michigan State University, East Lansing, MI USA 48824

A diploid, self-fertilizing plant with a small genome, Lotus japonicus, has been proposed as a model legume system for molecular genetic analysis of determinate nodule formation. Lotus japonicus appears to have outstanding potential as a model legume system since in addition to its relatively small genome (about 400Mb), it has several favorable characteristics, including short generation time, and availability of high frequency transformation and regeneration protocols. To contribute to the development of this model legume system we have initiated both molecular and genetic analyses to clone novel nodule specific genes and to identify novel loci important for symbiotic nitrogen fixation. In this presentation we will focus on our recent progress in the construction and analysis of a L. japonicus expressed sequence tag (EST) library. A range of ESTs associated with late developmental events during nodule organogenesis were identified using mRNA differential display; 110 differentially displayed polymerase chain reaction products were cloned and analyzed. Of 88 unique cDNAs obtained, 22 shared significant homology to DNA/protein sequences in the respective databases. This group comprises, among others, nodule-specific homologues of protein phosphatase 2C, transporter proteins, and a nodule-specific form of cytochrome P450. The kinetic of mRNA accumulation of the majority of the ESTs analyzed were found to resemble the expression pattern observed for the L. japonicus leghemoglobin gene. These results indicate that the newly isolated molecular markers correspond to the genes induced during late developmental stages of L. japonicus nodule organogenesis and provide important, novel tools for the study of nodulation.

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