Conserved C3H/APX bifunctionality coordinates lignin deposition and plant growth in Brachypodium and Populus.
Zhu W, Singh-Bakala H, Liu B, Bewg W, Bentelspacher M
Crispr
Poplar and other fast-growing trees used in bioenergy and timber production could be precisely engineered for softer lignin — wood that's easier to break down into fuel or paper — now that we know exactly which gene controls the on/off switch.
Plants have a special protein that does two things at once: it helps build the tough, woody material in stems and also neutralizes harmful molecules that can damage cells. Researchers snipped out the gene responsible for this protein in a grass and in poplar trees, and both plants became stunted and weak. When they fed the plants a key building block that the missing protein normally makes, the plants recovered — proving that making woody material, not managing cell damage, is what keeps plants growing strong.
Key Findings
CRISPR knockout of the C3H/APX gene in Brachypodium grass reduced lignin content and altered its chemical composition, causing impaired growth that was rescued by supplying caffeate or ferulate externally.
Elevated hydrogen peroxide (H2O2) in knockout mutants was not the cause of growth defects — adding catalase to neutralize H2O2 did not restore plant growth, pointing to disrupted lignin biosynthesis as the primary culprit.
Double-gene knockouts (both C3H/APX paralogs) caused severe developmental failure in both species: near-lethality in Brachypodium and complete inability to regenerate from tissue culture in poplar.
chevron_right Technical Summary
Scientists used CRISPR gene editing to confirm that a single plant enzyme performs two critical jobs at once: protecting cells from oxidative damage and building lignin, the woody material that gives plants their structure and strength. Disrupting this dual-purpose enzyme in grasses and poplar trees stunted growth and weakened cell walls, revealing that lignin production is the primary driver of healthy plant development.
Abstract Preview
Cytosolic ascorbate peroxidases (APXs) have been proposed to have bifunctional 4-coumarate 3-hydroxylase (C3H) activity, linking redox regulation to lignin biosynthesis in plants. Although this dua...
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Brachypodium is a genus of plants in the grass family, widespread across much of Africa, Eurasia, and Latin America. The genus is classified in its own tribe Brachypodieae.