Genomic organization and expression properties of the VfENOD5 gene from broad bean (Vicia faba L.)

A full-length cDNA encoding the broad bean (Vicia faba L.) early nodulin Vf ENOD5 was isolated from a nodule cDNA library. In addition to the ENOD5 hom ologues from other legumes the derived VfENOD5 amino acid sequence also dis played homologies to the phytocyanin-related nodulins GmENOD55-2, MtENOD16, and MtENOD20. A close inspection of the ENOD5 proteins from broad bean, pe a and vetch indicated that all these nodulins possess a putative C-terminal GPI-anchor signal sequence. This novel finding supports the hypothesis tha t ENOD5 is an arabinogalactan protein. Tissue print hybridizations revealed that the broad bean ENOD5 gene was not only expressed in the central tissu es of root nodules. In contrast to other legumes hybridizing transcripts we re also be detected in a narrow zone within the peripheral nodule tissues. Sequence analysis of a genomic clone indicated the presence of a single int ron interrupting the VfENOD5 coding region at a position precisely correspo nding to the MtENOD16 and MtENOD20 introns. (C) 2000 Elsevier Science Irela nd Ltd. All rights reserved.