Narrow-sense heritability was estimated at 0.35 for seedling length upon infection in the M. truncatula collection, and we detected a single locus in the last third of chromosome 4 (Fig. 1B) with two significant SNPs (P≤10–6) located at positions –4251 and –2467 upstream of the predicted ATG codon of RAD1, a GRAS (GAI, RGA, SCR) transcription factor-encoding gene (Medtr4g104020) (Table 1; Supplementary Fig. S2; Supplementary dataset S1E). This evidence concerns the gene RAD1 and infection.