Expression profile of monolignol biosynthetic genes analyzed by quantitative reverse transcription-PCR. The sequences were retrieved from the SUCEST database based on the annotated genes from Arabidopsis, sorghum, rice, and maize. YR, Young internode rind; IR, intermediate internode rind; MR, mature internode rind; YP, young internode pith; IP, intermediate internode pith; MP, mature internode pith. IACSP04-529 is the genotype with higher lignin levels, and IACSP04-683 is the genotype with lower lignin levels. Statistical analysis is found in Supplemental Table S3.