Phylogenetic and Cophylogenetic Analyses of the Leaf-Nodule Symbiosis inArdisiaSubgenusCrispardisia(Myrsinaceae): Evidence from Nuclear and Chloroplast Markers and BacterialrrnOperons

Abstract

Premise of research. Leaf-nodule symbiosis represents an intriguing relationship between angiosperms and bacteria. In leaf-nodulated Ardisia (subgenus Crispardisia), it has been hypothesized that the bacterial symbionts, which are also observed in reproductive organs, are transmitted to the next generation in a vertical and closed manner. We tested this hypothesis by using molecular approaches to locate the symbionts within hosts and to conduct host-symbiont cophylogenetic analyses.Methodology. Universal primers were used to amplify bacterial rrn operon from field-collected Crispardisia for identification of symbionts and design of symbiont-specific primers for PCR detection. The relationships of symbionts from 11 Crispardisia taxa with 60 validly named species in the same genus were analyzed. The monophyly of the hosts was also explored by constructing a phylogeny of Ardisia based on nuclear ribosomal internal transcribed spacer (nrITS) and three chloroplast markers from 36 taxa belonging to nine subgene...