CHARACTERIZATION OF GMENOD40, A GENE SHOWING NOVEL PATTERNS OF CELL-SPECIFIC EXPRESSION DURING SOYBEAN NODULE DEVELOPMENT

In this paper, the soybean 'early nodulin' clone pGmENOD40 is characte rized. The GmENOD40 encoded protein does not contain methionine and do es not show homology to proteins identified so far. In situ hybridizat ions showed that this gene has a complex expression pattern during dev elopment of determinate soybean nodules. At early stages of developmen t transcription is induced in dividing root cortical cells, the nodule primordium and the pericycle of the root vascular bundle. In mature s oybean nodules, the gene is expressed in the uninfected cells of the c entral tissue and in the pericycle of the nodule vascular bundles. Stu dies on nodules devoid of intracellular bacteria and infection threads , showed that the expression of the gene in the nodule primordium is i nduced in these empty nodules, while the induction of the GmENOD40 gen e in the nodule vascular bundle requires the presence of intracellular bacteria or infection threads. A pea cDNA clone homologous to GmENOD4 0 was isolated to enable in situ hybridization studies on indeterminat e nodules. The expression patterns in both determinate and indetermina te nodules suggests that the ENOD40 protein might have a transport fun ction.