Exploring associations among lignin biosynthesis gene expression, anatomy, and digestibility in Megathyrsus maximus cultivars

Abstract

Context Megathyrsus maximus (Jacq.) B.K.Simon & S.W.L.Jacobs is a fast-growing perennial grass species used as forage for livestock production suitable for grazing and cut-and-carry systems, depending on management in tropical and subtropical regions. Aims This study evaluated the expression of genes related to lignin biosynthesis during different phenological stages in leaf blades and stems of five cultivars. In addition, their effects on anatomical and nutritive variables were studied. Methods A 2-year field experiment was conducted involving five M. maximus cultivars evaluated at three phenological stages. Agronomic, nutritive, and anatomical variables, as well as lignin biosynthesis genes, were analyzed in leaf blades and stems. Key results Gene expression analyses showed that lignin biosynthesis genes were upregulated during maturation, with cultivar-specific responses. Notably, COMT was significantly upregulated in green panic leaf blades but remained unchanged in Vencedor, indicating differences in regulatory control. In stems, Vencedor showed stronger gene activation at later stages, supporting anatomical and biochemical evidence of enhanced lignification. Significant differences were observed in anatomical and nutritive variables among the cultivars. Vencedor consistently exhibited higher fiber fractions and lower ruminal dry-matter disappearance, indicating reduced digestibility, whereas Mutale showed lower neutral detergent fiber accumulation, particularly at flowering, highlighting its potential to improve nutritive value. Conclusions The gene expression patterns identified provide insights for molecular breeding strategies in M. maximus, with potential implications for improving forage digestibility and utilization. Implications Developmental regulation of lignin biosynthesis influences forage maturity and digestibility. The gene expression data generated provide a framework for future research to identify superior cultivars and optimize selection strategies in grass breeding programs.