Data and analysis scripts for the paper: Resource acquisition and allocation traits in symbiotic rhizobia with implications for life-history outside of legume hosts

Abstract

This repository contains all analysis scripts and data files for Katherine Muller's first dissertation chapter: Resource acquisition and allocation traits in symbiotic rhizobia with implications for life-history outside of legume hosts. The data are being released to meet a publisher's data sharing requirements. The paper addresses two gaps in knowledge needed to understand how polyhydroxybutyrate (PHB), a storage compound accumulated by many nitrogen-fixing rhizobia during interactions with legume hosts, contributes to the in the evolution of the legume rhizobia mutualism. Part 1 provides evidence for wide-ranging, heritable phenotypic variation within natural rhizobia populations in the amount of PHB stored during symbiosis. The conclusions are based on observations of phenotypic variation in rhizobial PHB per cell measured in the field (soybean and Chamaecrista fasciulata) and in greenhouse plants inoculated with field soil, plus experiments with rhizobia isolates showing high heritability in PHB per cell within soybean nodules. Part 2 explores the implications of heritable PHB variation for variation in fitness during the free-living stage using modeling and laboratory experiments. The model shows that the levels of PHB accumulated in nodules could potentially support survival functions for many years after symbiosis, based on published metabolic parameters and soil temperature measurements. The experiments compared survival and PHB use among rhizobia isolates with heritable variation in initial PHB supply, incubated in starvation cultures for over a year. The results on survival were inconclusive (partially due to contamination), but the results on PHB use suggest that variation in PHB accumulation in nodules could contribute to fitness of individual rhizobia long after they are released into the cell.