Evolution of coumaroyl conjugate 3‐hydroxylases in land plants: lignin biosynthesis and defense

Abstract

Summary Multiple adaptations were necessary when plants conquered the land. Among them were soluble phenylpropanoids related to plant protection and lignin necessary for upright growth and long‐distance water transport. Cytochrome P450 monooxygenase 98 (CYP98) catalyzes a rate‐limiting step in phenylpropanoid biosynthesis. Phylogenetic reconstructions suggest that a single copy of CYP98 founded each major land plant lineage (bryophytes, lycophytes, monilophytes, gymnosperms and angiosperms), and was maintained as a single copy in all lineages but the angiosperms. In angiosperms, a series of independent gene duplications and losses occurred. Biochemical assays in four angiosperm species tested showed that 4‐coumaroyl‐shikimate, a known intermediate in lignin biosynthesis, was the preferred substrate of one member in each species, while independent duplicates in Populus trichocarpa and Amborella trichopoda each showed broad substrate ranges, accepting numerous 4‐coumaroyl‐esters and ‐amines, and were thus capable of producing a wide range of hydroxycinnamoyl conjugates. The gymnosperm CYP98 from Pinus taeda showed a broad substrate range, but preferred 4‐coumaroyl‐shikimate as its best substrate. In contrast, CYP98s from the lycophyte Selaginella moellendorffii and the fern Pteris vittata converted 4‐coumaroyl‐shikimate poorly in vitro, but were able to use alternative substrates, in particular 4‐coumaroyl‐anthranilate. Thus, caffeoyl‐shikimate appears unlikely to be an intermediate in monolignol biosynthesis in non‐seed vascular plants, including ferns. The best substrate for CYP98A34 from the moss Physcomitrella patens was also 4‐coumaroyl‐anthranilate, while 4‐coumaroyl‐shikimate was converted to lower extents. Despite having in vitro activity with 4‐coumaroyl‐shikimate, CYP98A34 was unable to complement the Arabidopsis thaliana cyp98a3 loss‐of‐function phenotype, suggesting distinct properties also in vivo.

NO GAMETOPHORES 2 Is a Novel Regulator of the 2D to 3D Growth Transition in the Moss Physcomitrella patens

“…[32][33][34] As such, we hypothesize that blocking metabolic flux into the ascorbic acid pathway in which both PpNOG2 and PpCYP98A3 play a role would lead to a similar overaccumulation of flavonoids and perturbation of auxin homeostasis. This hypothesis is consistent with the Ppnog2-R mutant phenotype, with the observation that loss of PpCYP98A3 function leads to the formation of gametophores that undergo early developmental arrest, 28,35 and the known role of auxin in gametophore development. 31,36 To experimentally validate that auxin homeostasis is disrupted in Ppnog2-R mutants, we monitored the transcript accumulation profiles of a number of auxin-responsive genes in controlled conditions: auxin-inducible PpDOX and PpRSL4 and auxin-repressed PpCBS.…”

NO GAMETOPHORES 2is a novel regulator of the 2D to 3D growth transition in the mossPhyscomitrium patens

“…As such we hypothesize that blocking metabolic flux into the ascorbic acid pathway in which both PpNOG2 and PpCYP98A3 play a role, would lead to a similar overaccumulation of flavonoids and perturbation of auxin homeostasis. This hypothesis is consistent with the Ppnog2-R mutant phenotype, with the observation that loss of PpCYP98A3 function leads to the formation of gametophores that undergo early developmental arrest [28,34], and the known role of auxin in gametophore development [30,35].…”

Phenolamides in plants: an update on their function, regulation, and origin of their biosynthetic enzymes

“…In wheat, CYP98A11 and CYP98A12 were reported for the first time to effectively hydroxylate p-coumaroyl tyramine in vitro (Morant et al, 2007). More recently, high substrate plasticity has been demonstrated for some members of the CYP98A family among terrestrial plants, some of them being able to hydroxylate in vitro the hydroxycinnamic moiety of phenolamides (Alber et al, 2019). The CYP98A family is widely distributed among terrestrial plants and mainly dedicated to catalyze the hydroxylation of the p-coumaroyl shikimate ester for the biosynthesis of monolignols (Alber and Ehlting, 2012).…”

“…The CYP98A family is widely distributed among terrestrial plants and mainly dedicated to catalyze the hydroxylation of the p-coumaroyl shikimate ester for the biosynthesis of monolignols (Alber and Ehlting, 2012). However, in angiosperms, a second copy of CYP98A has also been reported with a wide range of substrates among phenolic compounds (Alber et al, 2019). This additional copy may be recruited to catalyze the decoration of new phenolic compounds such as phenolamides.…”