Root type and soil phosphate determine the taxonomic landscape of colonizing fungi and the transcriptome of field-grown maize roots

Key findingOur data illustrates for the first time that root type identity and phosphate availability determine the community composition of colonizing fungi and shape the transcriptomic response of the maize root system.\n\nSummaryO_LIPlant root systems consist of different root types colonized by a myriad of soil microorganisms including fungi, which influence plant health and performance. The distinct functional and metabolic characteristics of these root types may influence root type inhabiting fungal communities.\nC_LIO_LIWe performed internal transcribed spacer (ITS) DNA profiling to determine the composition of fungal communities in field-grown axial and lateral roots of maize (Zea mays L.) and in response to two different soil phosphate (P) regimes. In parallel, these root types were subjected to transcriptome profiling by RNA-Seq.\nC_LIO_LIWe demonstrated that fungal communities were influenced by soil P levels in a root type-specific manner. Moreover, maize transcriptome sequencing revealed root type-specific shifts in cell wall metabolism and defense gene expression in response to high phosphate. Furthermore, lateral roots specifically accumulated defense related transcripts at high P levels. This observation was correlated with a shift in fungal community composition including a reduction of colonization by arbuscular mycorrhiza fungi as observed in ITS sequence data and microscopic evaluation of root colonization.\nC_LIO_LIOur findings point towards a diversity of functional niches within root systems, which dynamically change in response to soil nutrients. Our study provides new insights for understanding root-microbiota interactions of individual root types to environmental stimuli aiming to improve plant growth and fitness.\nC_LI