Changes in DNA content during rhizobial nodule development in Lupinus luteus L. 2

Both autoradiographic and immunocytochemical in situ hybridization techniques were used to determine the relative number of leghemoglobin-coding sequences in the apical root meristem and in the endopolyploid root hair zone cortex of uninfected plants as well as in nodule cortex and bacteroid-containing tissue in Lupinus luteus L. A higher number of hybridization sites, despite of a similar ploidy level, was found in nuclei of bacteroid-containing cells than in nuclei of root parenchyma or nodule cortex cells. Amplification of leghemoglobin-coding sequences is suggested as one of the mechanisms involved in bacteroid-related induction of leghemoglobin synthesis. (author)