Is Nitrogenase-Linked Respiration Regulated by Osmocontractile Cells in Legume Nodules?

Observing that a decrease in nodule conductance to oxygen diffusion (gno) was associated with changes in shape and size of nodule cortical cells we hypothesized that the energetic metabolism supporting N2 fixation in the Rhizobium-legumz symbiosis would be regulated by contraction / expansion of nodule inner-cortex (IC) cells (Serraj et al., 1995). Recent circumstancial evidences, summarized here, support this hypothesis and show relations with nodule carbon metabolism.