Isolation of Legume Root Nodule Protoplasts

Abstract

INTEREST has developed in the use of cultured cells for establishing symbiosis between Rhizobium and plant cells in vitro¹, and in the genes controlling nodulation and the regulation of nitrogen fixation². It has, however, been impossible to isolate single cells from infected nodules. Such infected nodule cells would be particularly useful for biochemical studies on nitrogen fixation of infected cells in vitro. Recent studies on the somatic hybridization of plants by the fusion of isolated protoplasts suggest that hybridization between legumes and non-legumes may afford a means of transferring the genetic capability of symbiotic nitrogen fixation from legumes to non-legumes³. Protoplasts can be readily isolated from leaves and many other plant tissues using cell wall degrading enzymes, and these naked single cells can often be readily cultured in vitro⁴. We have therefore investigated the possibility of isolating protoplasts from legume root nodules.