Rhizosphere Community Stress Response in Lactuca

 

The rhizosphere is the zone of soil under the direct influence of plant roots. A growing body of work suggests that both plant genotype and age influence the selection and succession of bacterial communities in the rhizosphere.Know factors influencing the development of rhizosphere communities include plant exudation, root surface chemistry and root system architecture.Abiotic stress conditions such as drought, flood and nutrient depletion may also play a role in shaping rhizosphere communities.To test if rhizobacterial communities are reproducible across these abiotic stress conditions, a culture independent technique called terminal restriction fragment length polymorphisms (T-RFLPs) was used to characterize bacterial communities associated with domesticated lettuce, Lactuca sativa, and its wild progenitor, Lactuca serriola.A member of the Composite family, lettuce is an ideal model to study because it is easy to cultivate and is relevant to both agriculture and the study of invasive species. By identifying species-specific differences in bacteria communities, future studies may be able to identify the gene loci involved in plant-bacteria interactions in the rhizosphere.Results show a similar community composition between species within a stress condition.  Differences between L. sativa and L. serriola were due to many differences of small effect-size when considering peak area.  Because wild and domestic lettuce tended to cluster together within each stress condition, abiotic stress appears to be a larger influence on the community structure than plant species.