Initial stages in the morphogenesis of nitrogen-fixing stem nodules of Sesbania rostrata.

摘要: Morphogenesis of stem nodules in Sesbania rostrata was studied over a period 6 days after inoculation with an appropriate species Rhizobium. Nodulation sites were initially slightly raised, circular areas 0.3 to 0.6 mm diameter and 4 5 apart vertical rows along the length stem. Each site underlaid by adventitious root primordium. A became susceptible infection specific Rhizobium sp. when primordium broke through epidermis, leaving fissure. Rhizobia multiplied within this fissure colonized exposed intercellular spaces. The extended inward as narrow, branched threads moved into cortical meristematic zone, where cell division initiated, invagination thread branches adjacent plant cells followed. released surrounded immediately membrane. Intracellular rhizobia divided actively, leading bacteroid-filled cells. Infected enlarged coalesced nodule matured. Images