Strigolactone as a putative signal compound in G. elata in its mycoheterotrophic symbiotic relationship with A. mellea. a Overview of proposed signaling and nutrition transfer in G. elata. The red-labeled genes are expanded in the G. elata genome and P-value of Fisher’s exact test of gene number <0.05 (Supplementary Tables 38, 40, 41). ANT, ANT1-like aromatic and neutral amino acid transporters; ArgJ, glutamate N-acetyltransferase; CCD, carotenoid cleavage dioxygenases; COS, chitooligosaccharides; DMI3, does-not-make-infections 3 subfamily; LOS, lipochitooligosaccharides; LysM, LysM-receptor-like kinases; PDR, ABC transporter. P1, p-value of Fisher’s exact test of gene number in G. elata genome compared to P. equestris, D. officinale, A. comosus, and A. thaliana; P2, p-value of Fisher’s exact test of gene number in G. elata genome compared to A. thaliana; P3, p-value of Fisher’s exact test of gene number in G. elata genome compared to A. comosus; P5, p-value of Fisher’s exact test of gene number in G. elata, P. equestris, and D. officinale genome compared to A. comosus and A. thaliana. b Branching of A. mellea hyphae was significantly promoted after strigolactone treatment (Supplementary Fig. 13). Scale bar was 5 mm. c Cross sections and micrographs of immature G. elata tubers in association with A. mellea (A, epidermis; B, cortex; C, inner parenchyma cells, Supplementary Fig. 14). The black scale bar on the left was 100 μm and the white one on the right was 20 μm