Ethylene Inhibitors Partly Restore Nodulation to Pea Mutant E 107 (brz)

E107 (brz) is a pleiotropic mutant of pea (Pisum sativum L. cv Sparkle) characterized by low nodulation, leaf necrosis, excessive ion accumulation, and decreased plant size. The defective nodulation of E107 was studied by light microscopy of lateral roots. The number of infections per centimeter of lateral root was only a third that of Sparkle. Moreover, most of the infections were aborted early; i.e. in only 14% of the infections did the infection thread penetrate beyond the epidermis. Nodulation of E107 was partly restored by treating the plant with the ethylene inhibitors aminoethoxyvinylglycine (AVG) or Ag(+). Treatment with Ag(+) did not increase the number of infections, but half of the infections went to completion. Ag(+) and AVG did not alter the size of the mutant, the accumulation of cations in its shoots, nor the leaf necrosis. Thus, in E107, nodule development can be uncoupled from other pleiotropic characteristics.