AsNODc22, a novel nodulin gene of Astragalus sinicus, encodes a protein that localizes along the cell wall of bacteria-infected cells in a nodule.

A novel nodulin gene, AsNODc22, was isolated from Astragalus sinicus cv. Japan (Renge-sou) by differential screening. The transcript of AsNODc22 was nodule specific, and its size was approximately 0.8 knt. AsNODc22 encoded an unknown ORF containing a putative signal peptide and a pair of similar hepta-peptides (CSAQVSC, CSAQLSC). For immunological study, antiserum against AsNODc22 protein was prepared in mice. By immunoblot analysis, the antiserum detected a nodule specific band at approximately 18 kDa. Immunofluorescence microscopy was used to observe localization of the gene product in the nodule. The signals were seen along the cell wall of bacteria-infected cells, but no significant signals were seen on uninfected cells.