Involved in the infection process during the plant-rhizobium interaction. May also have an additional function in the proliferation of the bacteria. Expressed during rhizobium-induced nodule formation. In 4-day old nodules it is found in all the cells of the center of the nodule primordium and also occurs in the root cortical cells containing the infection thread. At day 5, expression is seen in the complete central tissue and at day 20, expressed in the complete prefixation zone II and is present at a similar level throughout the zone. In the distal part of the prefixation zone II it is probably expressed in all cells, whereas in the proximal part, found only in the infected cells. Expression decreases at the transition of prefixation zone II into interzone II-III. Belongs to the plant proline-rich protein superfamily. ENOD12 family.