Endoreduplication is essential for symbiotic cell differentiation in Medicago truncatula

摘要

Plant organ development is a constant interplay between cell cycle and differentiation programs. Various stages of nodule development are controlled by differential regulation of the cell cycle. As a first step, the rhizobial Nod factors activate thecell cycle in the nodulation sensitive root zone. In Medicago sativa roots the G0-arrested cortical cells dedifferentiate and reenter the cell cycle in front of the protoxylem poles. These cells undergo the G1/S transition, however, the cell cycle is completed by cell division only in the inner cortex. Maintenance of mitotic activity and recruitment of the neighbouring cells lead to extensive but localized cell proliferation and formation of the nodule primordium.