Implications of Below-Ground Allelopathic Interactions of and Microorganisms for Phosphate Availability and Habitat Maintenance

Toxic breakdown products of young (L.) Crantz, glucosinolates can eliminate microorganisms in the soil. Since microorganisms are essential for phosphate cycling, only insensitive microorganisms with phosphate-solubilizing activity can improve phosphate supply. In this study, P-labeled phosphate, inductively coupled plasma mass spectrometry and pot experiments unveiled that not only and used as phosphate-solubilizing inoculants, but also intrinsic soil microorganisms, including , and the assemblies of root-colonizing microorganisms solubilized as well phosphate from apatite, trigger off competitive behavior between the organisms. Driving factors in the competitiveness are plant and microbial secondary metabolites, while glucosinolates of and their breakdown products are regarded as key compounds that inhibit the pathogen , but also seem to impede root colonization of . On the other hand, fungal diketopiperazine combined with glucosinolates is fatal to . The results may contribute to explain the contradictory effects of phosphate-solubilizing microorganisms when used as biofertilizers. Further studies will elucidate impacts of released secondary metabolites on coexisting microorganisms and plants under different environmental conditions.