Identification of key enzymes in lignocellulose biosynthesis from dynamic observations in maize stalks
2024
Xiaoxu Zhan | Fanlei Kong | Qinlin Liu | Tianqiong Lan | Fan Liu | Xinglong Wang | Xia Du | Xiang Chen | Jichao Yuan
Maize stalk lignin and cellulose contents are linked to lodging resistance, disease resistance, feed quality and ethanol conversion efficiency. After the six-leaf stage of maize (V6), these constituents are biosynthesized and accumulated under the control of related enzymes and genes. However, the key enzymes, critical MYB transcription factors, and their dynamic alterations pattern under natural field circumstances are still unknown. Hence, we selected five cultivars with significant differences in lignocellulose content and lodging resistance as testing materials, performed field experiments for two years, and investigated the dynamics of lignin and cellulose content, related enzyme concentrations, and gene expression levels in the 3rd and 5th internodes above the ground after V6. The results showed that lignin and cellulose content increased after V6, stabilizing during the silking stage. This study identified COMT (caffeic acid 3-O-methyltransferase), TAL (tyrosine ammonia-lyase) and PAL (phenylalanine ammonia-lyase) as the key enzymes of lignin biosynthesis, while ZmCOMT, ZmCesA10 and ZmCesA8 were identified as essential genes. ZmMYB8, ZmMYB31 and ZmMYB39 were involved in regulating the expression of genes related to lignin synthesis, with ZmMYB31 potentially acting as a key negative regulator, while ZmMYB39 and ZmMYB8 acting as positive regulators. The study also found that around 14 d after V6 was a critical stage for regulating lignocellulose synthesis in the 3rd to 5th basal internode. This provides a theoretical foundation for developing regulatory techniques and breeding new cultivars to enhance lodging and disease resistance as well as the utility of maize stalks.
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