Wall fractions extracted with mild reagents such as ammonium oxalate and sodium carbonate generally contain large amounts of GalA along with rhamnose (Rha), arabinose (Ara), galactose (Gal), glucose (Glc), xylose (Xyl), and mannose (Man) and, thus, are considered to be enriched in pectin.
During fractionation of the cell wall material, three fractions of pectin were obtained: the water-soluble fraction (WSF – pectin that is loosely associated with the cell wall); the CDTA-soluble fraction (CSF – pectin that is enriched in bound ions); and the Na2CO3-soluble fraction (NSF – pectin that is enriched in covalently bound ions).
Interestingly, two CAZy families involved in pectin degradation are enriched in P. digitatum compared to P. chrysogenum.
Fruits and vegetables are rich in pectin, whereas seeds are enriched in storage polysaccharides such as galactomannan, starch and inulin.
Genes known to be involved in fungal pathogenicity, including polygalacturonase (PG) and pectin lyase, were enriched in plant pathogens.
Furthermore, with regard to GO terms related to the hydrolysis of lignocellulose, 'GO 0045490; pectin catabolic process' was enriched in the list of genes with increased transcripts at 6 h carbon starvation and 6 h straw.
These results indicate that pectin of 02-5B-318R spikenrichedrinhedomainsmains less susceptible to PGs of F. graminearum secreted at early stages of infection [ 8].
The outermost thin layer of middle lamella and primary cell wall, frequently referred to as the compound middle lamella, is rich in pectin and xyloglucan (XG) and is heavily lignified, whereas the inner thicker secondary-wall layers are enriched in cellulose and in hemicelluloses such as xylans and mannans, but are thought to contain relatively less lignin.
Additionally, putative α-rhamnosidases (GH78) were enriched in the SAC and rumen communities relative to the drywood-eating termite hindgut microbiome, although the main rhamnose-containing heteropolysaccharide, pectin, is more prevalent in dicot cell walls than grass cell walls [10].
Not surprisingly, the xylan and pectin regulons were enriched for hemicellulose and pectin hydrolytic genes but showed limited induction for AA genes.
