Exploring the Effect of ATP-Binding Cassette Transporter Mutants of Arabidopsis thaliana on Rhizobacterial Populations from Old New England Soil

Plants release up to 30% of their photosynthates as organic compounds into the soil surrounding their roots, which leads to increased microbial metabolism, improved plant health and increased crop yields. Studies have shown that plants selectively influence microbial communities through this rhizosphere effect. The released phytochemicals, called exudates, may lead to symbiotic, parasitic or pathogenic plant-microbe interactions and stimulate biogeochemical cycling, and play a role in plant signaling and defense. Recently, ATP-binding cassette (ABC) transporters from several plants, including Arabidopsis thaliana, have been shown to be involved in secreting secondary metabolites into the rhizosphere.  Little is known about how exuded phytochemical via ABC transporters impact soil bacterial communities. Here, to determine the role of ABC transporters in exuding chemicals that change rhizobacterial populations, ABC transporter mutant plant lines growing in old New England soil will be investigated. In this experiment, we will grow single ABC transporter mutant plant lines and wild type Arabidopsis ecotype Columbia controls in containers of field soil.  Five replicates of the genotypes will be grown in randomized design under lights under long-day conditions in a growth room.  Rhizosphere soil will be collected from roots and following the extraction of community DNA, terminal restriction fragment length polymorphisms will be used to create community fingerprints for comparison between plants. The hypothesis is that the exudation mutants will create significantly different fingerprints from each other and wild type controls.