Fig. 5

Effect of biochar-amendment to the growth medium on H₂0₂ accumulation and lignin levels in the rice roots. a H₂O₂ content per gram of root was measured upon reaction with KI and detection using a CLARIOstar Microplate Reader at 390 nm. The bars represent the mean ± SE of four replicates, each containing a pool of six roots. Different letters indicate significant differences (Duncan’s Multiple Range Test at p ≤ 0.05). b Relative transcript levels of the H₂O₂ synthesis gene (OsRbohB) at 24 hpi were analyzed using qRT-PCR. The gene expression levels were normalized using three internal reference genes, OsEXP, OsEif5C and OsEXPnarsai. The data shown are the relative transcript levels compared with the control roots (expression level set at 1). The bars represent the mean expression level ± SE from two independent biological replicates, each containing a pool of 6 plants. Asterisks indicate significantly different expression levels in comparison with water-treated control roots. (p ≤ 0.05). c Lignin content in the roots of rice amended with 1.2 % biochar or water was determined using the acetylbromide assay. Root samples were collected before inoculation (0 h) and 24 hpi. The bars represent the mean ± SE of the lignin content of 6 plants. Different letters indicate significant differences (Duncan’s multiple range test at p ≤ 0.05)