Putative Seedling Ferulate Ester (sfe) maize mutant: morphology, biomass yield, and stover cell wall composition and rumen degradability
Ferulate cross-linking of lignin to arabinoxylan contributes to poor cell wall degradability of grass forages. We hypothesized that reduced ferulate ester deposition will result in formation of fewer ferulate cross links and improved degradability. Objectives were to determine if the putative seedling ferulate ester (sfe) maize (Zea mays L.) mutant, selected for reduced ferulate esters in seedling leaves, (i) exhibits reduced ferulate ethers; (ii) alters morphology, yield, and cell wall concentration and composition; and (iii) changes degradability. Four near-isogenic sfe lines and backcrosses to W23 were compared with the inbred W23 in replicated field trials. Leaf blade, sheath, and stem of immature (1-m plant height) and mature (silage) growth stages were analyzed for ferulate esters and ethers, cell wall concentration and composition, and in vitro rumen degradability. The sfe lines were taller and had greater internode cross-sectional area than W23. Plant yield was greater at silage maturity for sfe lines and backcross lines yielded more than sfe. Mature plant parts of sfe lines had lower ferulate ester concentrations than W23. At silage stage sfe lines had less ferulate ethers, small reductions in cell wall concentration, and shifts in composition. Immature samples were inconsistent for cell wall traits and backcross lines were generally intermediate, regardless of maturity. Cell wall degradability was higher for the sfe mutant as hypothesized. Reducing ferulate-mediated cross-linking of lignin to arabinoxylan in the cell walls of maize stover appears to be an effective strategy for improving cell wall degradability, and the sfe mutant may offer an opportunity to identify a gene controlling ferulate deposition in grasses.