The role of D14-LIKE in the perception of arbuscular mycorrhizal signals in rice and its evolutionary significance in arbuscular mycorrhizal symbiosis

PhD project strategic theme: Bioscience for sustainable agriculture and food

Root colonisation by arbuscular mycorrhizal fungi (AMF) is tightly regulated by the plant depending on its physiological and developmental status. Mutation of the rice alpha/beta receptor DWARF14-LIKE (D14L) blocks arbuscular mycorrhizal symbiosis (AMS) and renders roots insensitive to fungal exudates (Gutjahr et al., 2015; Summers, unpublished). D14L appears to function as a central node for multiple inputs to pre-symbiosis signalling, as the d14l mutant is defective in the normal transcriptional reprogramming required to accommodate AMF (Summers, unpublished). D14L is hypothesised to function in a complex with D3 to degrade the transcriptional repressor SMAX1 in rice to direct a symbiotic response (Choi et al., in press). However, a detailed functional explanation for the severity of the d14l phenotype is lacking and how D14L ties together with other pre-symbiosis components remains unclear. The aim of this PhD is to elucidate the transcriptional networks downstream of D14L signalling by identifying key transcription factors regulated by SMAX1 and studying their connectivity and evolutionary conservation. To understand the D14L-SMAX1 regulon, analyses of mutant phenotypes and transcriptomics data, in conjunction with a large scale transcriptomics experiment, protein-protein interactions, and phylogenetics, will be used to investigate the importance of D14L signalling in AMS.