Assessment of below ground chemical communication by allelopathic cover crops in response to heterospecific neighbors
SUPERVISOR: Stephan HANN
PROJECT ASSIGNED TO: Alexandra BENNETT
Plants compete with one another for resources in a multitude of ways. A major strategy that some cover crops, such as buckwheat and black oat, utilize to compete is called allelopathy. These plants release compounds which reduce the growth and proliferation of other plants into the rhizosphere, a zone of intense physical and chemical interaction between plants, microorganisms, and the soil. These cover crops and compounds are of interest for their potential as a natural source of controlling weedy species in an agricultural setting. However, little is known about the specific molecules responsible for these allelopathic effects. My research aims to develop a novel liquid chromatography (LC) separation method which utilizes a dual column setup paired with quadrupole time of flight (Q-TOF) mass spectrometry (MS) to identify the specific compounds responsible. Using both a reverse phase pentafluorophenol (PFP) column in tandem with a porous graphic carbon (PGC) column allows for the separation of both polar and non-polar compounds in a single method (Fig 1). This analytical method will be used to assess the exudates from buckwheat and black oat plants that have been grown together with the weedy species pigweed and black grass (Fig 2). These samples, along with samples generated by collaborators utilizing other complimentary growth setups, will allow us to determine how the metabolites produced and exudated by the roots of buckwheat and black oat are altered in the presence of heterospecific neighbors.
Fig 1. Dual column setup. In phase A, pump one is sending aqueous solution through both pentafluorophenol (PFP) column and porous graphic carbon (PGC). After metabolites are retained onto both columns, a valve is switched to begin phase B. In phase B, each column has their own pump and LC gradient for analyte separation.
Fig 2. Rhizotron growth setup. Plants are grown between translucent plates at approximately a 45 degree angle. Cover crop species buckwheat and black oat are grown together with the weedy species pigweed and black grass. Root exudates can then be collected from each species through a variety of methods such as micro-suction cups (shown), root isolation and submersion into aqueous solution, and/or root traps.