Simultaneous Downregulation of MTHFR and COMT in Switchgrass Affects Plant Performance and Induces Lesion-mimic Cell Death
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ABSTRACT: Switchgrass (Panicum virgatum) has been developed into a model lignocellulosic bioenergy crop. Downregulation of caffeic acid O-methyltransferase (COMT), a key enzyme in lignin biosynthesis, led to altered lignification and increased biofuel yield in switchgrass. Methylenetetrahydrofolate reductase (MTHFR) mediated C1 metabolism provides methyl units consumed by COMT. It was predicted that co-silencing of MTHFR and COMT would have a more significant impact on lignification than either of the single genes. However, our results showed that strong downregulation of MTHFR in a COMT-deficient background led to altered plant growth and development, but no significant change in lignin content or composition was found when compared with COMT plants. Another unexpected finding is that the double MTHFR/COMT downregulated plants showed a novel lesion-mimic leaf phenotype. Molecular analyses revealed that the lesion-mimic phenotype was caused by the synergistic effect of MTHFR and COMT genes, with MTHFR playing a predominant role. Microarray analysis showed significant induction of genes involved in oxidative and defenserelated processes. The results demonstrated the lack of additive effects of MTHFR and COMT on lignification. Furthermore, this research revealed an unexpected role of the two genes in the modulation of lesion-mimic cell death as well as their synergetic effects on agronomic performance.
ORGANISM(S): Panicum virgatum
PROVIDER: GSE98676 | GEO | 2018/05/01
REPOSITORIES: GEO
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