Molecular Methods for Research on Actinorhiza

Abstract

Actinorhizal root nodules result from the interaction between a nitrogen-fixing 7actinomycete from the genus Frankia and roots of dicotyledonous trees and 8shrubs belonging to 25 genera within 8 plant families. Most actinorhizal plants 9can reach high rates of nitrogen fixation comparable to those found in root nodule 10symbiosis of the legumes. As a consequence, these trees are able to grow in poor and disturbed soils and are important elements in plant communities worldwide.13 While the basic knowledge of these symbiotic associations is still poorly under-14 stood, actinorhizal symbioses emerged recently as original systems to explore15 developmental strategies to form nitrogen-fixing nodules. Many tools have been16 developed in recent years to explore the interaction between Frankia and17 actinorhizal plants including molecular biology, biochemistry and genomics.18 However, technical difficulties are often encountered to explore these symbiotic19 interactions, mainly linked to the woody nature of the plant species and to the lack20 of genetic tools for their bacterial symbionts. In this chapter, we report an21 inventory of the main recent molecular tools and techniques developed for22 studying actinorhizae.