Impacts of amoebal diversity on crop growth:promotion and inhibition

Abstract

Protists are a little-researched component of soil food webs, though they are the primary consumers of bacteria. Microcosm experiments have revealed they stimulate plant root growth and commitment of carbon to mycorrhizal fungi, which in turn accelerates release of N sequestered in the bodies of their bacterial prey. This substantially increases plant biomass. Amoebal predation has been found to stimulate release of 2, 4, diacetylphloroglucinol (DAPG) by Pseudmonas fluorescens which is known to cause Induced Systemic Resistance (ISR) in plants and has been associated with pathogen-suppressive soils. Models of intense protist grazing in the rhizosphere indicate an increase of bacteria producing defensive toxins that have beneficial effects on plant health. Next gen sequencing techniques do not yet provide the flexibily required to identify potentially useful protist groups. Integrated farming methods already employ the N mobilizing effects of comparatively higher protist diversity and abundance, and this will likely increase with development of effective organic amendments and protist seeding methods.