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Analysis of Medicago truncatula Nodule Expressed Sequence Tags

January 2000 , Volume 13 , Number  1
Pages  62 - 71

János Györgyey , 1 , 2 Danièle Vaubert , 1 José I. Jiménez-Zurdo , 1 , 3 Celine Charon , 1 Liliane Troussard , 1 ádám Kondorosi , 1 and éva Kondorosi 1

1Institut des Sciences Végétales, CNRS, 91198 Gif-sur-Yvette, France; 2Institute of Plant Biology, Biological Research Center, Hungarian Academy of Sciences, H-6726 Szeged, Hungary; 3Departamento de Microbiología del Suelo y Sistemas Simbióticos, Estación Experimental del Zadín, CSIC, 18008 Granada, Spain

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Accepted 1 October 1999.

Systematic sequencing of expressed sequence tags (ESTs) can give a global picture of the assembly of genes involved in the development and function of organs. Indeterminate nodules representing different stages of the developmental program are especially suited to the study of organogenesis. With the vector ΛHybriZAP, a cDNA library was constructed from emerging nodules of Medicago truncatula induced by Sinorhizobium meliloti. The 5′ ends of 389 cDNA clones were sequenced, then these ESTs were analyzed both by sequence homology search and by studying their expression in roots and nodules. Two hundred fifty-six ESTs exhibited significant similarities to characterized data base entries and 40 of them represented 26 nodulin genes, while 133 had no similarity to sequences with known function. Only 60 out of the 389 cDNA clones corresponded to previously submitted M. truncatula EST sequences. For 117 cDNAs, reverse Northern (RNA) hybridization with root and nodule RNA probes revealed enhanced expression in the nodule, 48 clones are likely to code for novel nodulins, 33 cDNAs are clones of already known nodulin genes, and 36 clones exhibit similarity to other characterized genes. Thus, systematic analysis of the EST sequences and their expression patterns is a powerful way to identify nodule-specific and nodulation-related genes.

© 2000 The American Phytopathological Society