Cell Wall Characteristics of a Maize Mutant Selected for Decreased Ferulates

Abstract

The cross-linked nature of plant cell walls provides structural integrity for continued growth and development, but limits degradation and utilization by ruminants. In grasses a major cross-linking component is ferulic acid that is incorporated into cell walls as an ester linked residue on arabinoxylans. Ferulates can become coupled to each other and to lignin forming a highly cross-linked matrix of carbohydrates and lignin. Seedling ferulate ester mutants (sfe) were produced in maize using the transposon system and evaluated in feeding trials. The work described here was undertaken to characterize changes in the ferulate cross-linked nature as well as other components of the corn cell wall matrix in leaf, sheath and stem tissues. Total ferulates decreased modestly due to the mutation and were more apparent in leaf tissue (16% -18%) compared to sheath (+5 to −6% change) and stem (8% -9% decrease). The most significant changes were in the ether linked ferulates to lignin, both monomer and dehydrodiferulates (14% to 38% decrease). Other characteristics of the cell wall (lignin, neutral sugar composition) also showed modest changes. The change in total ferulates was modest, but led to improved animal performance. These findings suggest that relatively small changes can have a significant impact upon how well plant materials can be broken down and utilized by ruminants such as dairy cows.

Covalent interactions between lignin and hemicelluloses in plant secondary cell walls

“…In vivo evidence comes from a maize mutant (sfe) with reduced feruloylation. The sfe mutant has higher in vitro rumen digestibility [30,32]. Consistent with this, in animal feeding trials the sfe mutant led to reduced feeding but increased milk production, suggesting it is more digestible in vivo [33].…”

“…It has also been demonstrated that diferulates incorporate into lignin in vitro, suggesting even more complex structures involving multiple xylan molecules linked to each other can cross-link to lignin [28]. Quantification of ether-linked ferulates in grass cell walls, which includes xylan:xylan cross-links and xylan:lignin cross-links, suggests that 20-80% of ferulate is etherlinked [29,30].…”

Functional and nutraceutical properties of maize bran cell wall non-starch polysaccharides

“…[70] It represents about up to 4% of the maize bran cell wall. [71] Cell walls are widely utilized in a large number of foods, feed, and non-food sectors. [72] The main constituent of maize bran is non-starch polysaccharides, and 50% of that are Ferulated arabinoxylans (FAXs).…”

Tailoring renewable materials via plant biotechnology

“…With this biochemical knowledge, efforts to reduce the amount of ferulic acid synthesized in the cell wall have been attempted. For example, the maize mutant seedling ferulate ester ( sfe ) has reduced feruloylation, resulting in better forage digestibility [ 239 – 241 ]. Another example is the rice knock-out mutant xax1 , a family 61 glycosyl transferase ( gt61 ), which is responsible for the arabinosyl substitutions of the xylan backbone.…”