Lignin and Its Pathway-Associated Phytoalexins Modulate Plant Defense against Fungi

Abstract

Fungi infections cause approximately 60–70% yield loss through diseases such as rice blast, powdery mildew, Fusarium rot, downy mildew, etc. Plants naturally respond to these infections by eliciting an array of protective metabolites to confer physical or chemical protection. Among plant metabolites, lignin, a phenolic compound, thickens the middle lamella and the secondary cell walls of plants to curtail fungi infection. The biosynthesis of monolignols (lignin monomers) is regulated by genes whose transcript abundance significantly improves plant defense against fungi. The catalytic activities of lignin biosynthetic enzymes also contribute to the accumulation of other defense compounds. Recent advances focus on modifying the lignin pathway to enhance plant growth and defense against pathogens. This review presents an overview of monolignol regulatory genes and their contributions to fungi immunity, as reported over the last five years. This review expands the frontiers in lignin pathway engineering to enhance plant defense.

Mitigating biomass recalcitrance for plant‐based bioenergy production

“…5-hydroxylase, cinnamoyl CoA reductase, CAD, and peroxidases/laccases. 24,[109][110][111][112][113][114][115][116][117][118] The functions of the individual proteins in regulating lignin biosynthesis and genetic manipulations that influence lignin biosynthesis can be accessed from our previous review of article (Figures 1 and 2). 24 DNA motifs are rich in adenosine and cytosine (AC) elements that promote and largely influence lignin biosynthesis.…”

“…24,[109][110][111][112][113][114][115][116][117][118] The functions of the individual proteins in regulating lignin biosynthesis and genetic manipulations that influence lignin biosynthesis can be accessed from our previous review of article (Figures 1 and 2). 24 DNA motifs are rich in adenosine and cytosine (AC) elements that promote and largely influence lignin biosynthesis. The transcriptional factor MYB is rich in AC elements and mediates lignin synthesis gene expression; for example, MYB46 and its homologue MYB83 regulate the expression of lignin synthetic genes.…”

“…Lignin, cellulose, and hemicellulose have been recently targeted for conferring impermeability to SCW against external invasion. 24 Interestingly, resources for bioenergy production heavily depend on crop straws, which are mostly genetically programmed to produce more lignocellulosic polymers. Therefore, it is compelling to reduce the lignin content for sustainable use of plant biomass.…”

“…9,20,21 Enzymes that catalyse the synthesis of lignocellulosic polymers have been identified in many plant species. [22][23][24][25] Genetic transformation provides a cheaper way to reduce biomass recalcitrance and to increase and enhance the saccharification process. For example, deletion of the site-binding residues (W436 and P437) of cellulose synthase A4 (CESA4) reduces its binding affinity, leading to normal growth and thinner cell walls of plants, with a 50% improvement in the saccharification process in poplar plants.…”

Antimicrobial Peptide-Inspired Design of Amino-Modified Lignin with Improved Antimicrobial Activities

“…This is because lignin is a natural antimicrobial polymer. Plants deposit lignin in the secondary cell wall to defense against pathogens . Research with isolated lignin indicated that the antimicrobial mode of action of lignin involves the affinity to microbial cell surface and causing membrane destabilization, which do not induce drug resistance in pathogenic microbes .…”