THI1 expression and thiamine content in thi1 mutant roots. A, THI1 structure and position of the LORE1 insertion in the thi1 mutant. P1, P2, and P3 indicate the positions of fragments amplified with primer sets for qRT-PCR. a.a., Amino acids. B, THI1 expression in the thi1 mutant 2 weeks after inoculation with M. loti. P1, P2, and P3 indicate data obtained with the respective primer sets shown in A. Error bars indicate sd (n = 3). Significant differences from WTseg are shown (Student’s t test: **, P < 0.01). C, THI2 expression in the thi1 mutant. Expression levels were normalized to that of ubiquitin. Error bars indicate sd (n = 3). D, Thiamine content in thi1 mutant roots 3 weeks after inoculation with M. loti. Error bars indicate sd (n = 4). A significant difference from wild-type Gifu is shown (Student’s t test: *, P < 0.05).