The early nodulin gene, PsENOD7, is expressed in pea root nodules induced by Rhizobium leguminosarum bv. viciae, but not in other plant organs. In situ hybridization showed that this gene is transcribed during nodule maturation in the infected cells of the proximal part of the prefixation zone II. At the transition of zone II into interzone II–III, the level of PsENOD7 mRNA drops markedly. PsENOD7 has no significant homology to other genes. RFLP mapping studies have shown that PsENOD7 is located in linkage group I between the leghaemoglobin genes and sym2.
Kozik, A., Matvienko, M., Scheres, B., Paruvangada, V. G., Bisseling, T., van Kammen, A., ... Weeden, N. (1996). The pea early nodulin gene PsENOD7 maps in the region of linkage group I containing sym2 and leghaemoglobin. Plant Molecular Biology, 31, 149-156. https://doi.org/10.1007/BF00020614