Diverse Sorghum bicolor accessions show marked variation in growth and transcriptional responses to arbuscular mycorrhizal fungi

Sorghum is an important crop grown worldwide for feed and fibre. Like most plants, it has the capacity to benefit from symbioses with arbuscular mycorrhizal (AM) fungi, and its diverse genotypes likely vary in their responses. Currently, the genetic basis of mycorrhiza‐responsiveness is largely unknown. Here, we investigated transcriptional and physiological responses of sorghum accessions, founders of a bioenergy nested association mapping panel, for their responses to four species of AM fungi. Transcriptome comparisons across four accessions identified mycorrhiza‐inducible genes; stringent filtering criteria revealed 278 genes that show mycorrhiza‐inducible expression independent of genotype and 55 genes whose expression varies with genotype. The latter suggests variation in phosphate transport and defence across these accessions. The mycorrhiza growth and nutrient responses of 18 sorghum accessions varied tremendously, ranging from mycorrhiza‐dependent to negatively mycorrhiza‐responsive. Additionally, accessions varied in the number of AM fungi to which they showed positive responses, from one to several fungal species. Mycorrhiza growth and phosphorus responses were positively correlated, whereas expression of two mycorrhiza‐inducible phosphate transporters, SbPT8 and SbPT9, correlated negatively with mycorrhizal growth responses. AM fungi improve growth and mineral nutrition of sorghum, and the substantial variation between lines provides the potential to map loci influencing mycorrhiza responses. Here, we investigated sorghum bioenergy accessions for their physiological and transcriptional responses to four diverse species of arbuscular mycorrhizal fungi. Variation in mycorrhiza‐induced growth and nutritional responses was observed, and this set of lines shows diversity in both mycorrhiza responsiveness and dependence. Additionally, four sorghum mycorrhizal root transcriptomes were generated which enabled the identification of conserved and variable arbuscular mycorrhiza‐regulated sorghum genes. Genetically diverse sorghum lines show variation in their growth, nutrition, and transcriptional responses to several arbuscular mycorrhizal fungi.