Biology subjects

Suh, D.-Y.

Publications and source records attributed to Suh, D.-Y..

3 recordsLinked to original sources

bioRxiv2024

The polyketide pathway in sporopollenin biosynthesis is specific to land plants (Embryophyta)

Background and AimsSporopollenin (SP) is a complex biopolymer in the outer wall of spores and pollen and provides protection from environmental stresses. Its extraordinary chemical resistance, especially to acetolysis, was widely used to identify SP in biological specimens. This broad definition of SP led to claims for its widespread occurrence among diverse embryophyte and non-embryophyte taxa. We previously proposed a biochemical definition that can be used to distinguish genuine SP from other chemically resistant cell wall materials. The definition was centred on ASCL (Anther-Specific Chalcone synthase-Like), an embryophyte-specific enzyme of the polyketide pathway that provides precursors for SP biosynthesis. Herein, we examine the evolution and distribution of all five enzymes (CYP703A, CYP704B, ACOS, ASCL and TKPR) of the polyketide pathway and propose a new, more comprehensive definition of SP. MethodsWe performed BLASTp searches, phylogenetic tree construction, protein modeling and sequence analysis to determine the presence or absence of ACOS and TKPR in embryophytes and streptophytic algae. Key ResultsWe found evidence that all five enzymes of the polyketide pathway evolved from ancestral enzymes of primary metabolism and ACOS, ASCL and TKPR were co-selected during evolution. The dosage of all five genes has been subjected to strict evolutionary control and, in some taxa, synteny has provided a selective advantage. All five enzymes are present in embryophytes but absent in green algae, indicating that the polyketide pathway and therefore SP is embryophyte-specific. ConclusionsThe addition of the polyketide pathway in the definition of genuine SP will allow separation of SP from algaenans and other chemically resistant SP-like algal spore wall substances. This study further signifies SP as an evolutionary innovation unique to the embryophyte lineage and encourages research on possible evolutionary relationship between algal spore wall SP-like materials and embryophyte SP.

plant biology↗

bioRxiv2024

Genome-wide analysis of the class III peroxidase gene family in Physcomitrium patens and a search for clues to ancient class III peroxidase functions

Plant class III peroxidases (PRX) catalyze generation of reactive oxygen species and oxidation of various compounds including lignin precursors. PRXs function in cell wall metabolism, defense and stress responses. However, gene redundancy and catalytic versatility have impeded detailed functional characterization of PRX genes. The genome of the model moss Physcomitrium patens harbors a relatively small number (49) of PRX genes. Conserved architecture of four exons and three 001 introns, found in some algal PRX genes and in the PpPRX family, suggests that this architecture predated divergence of the green algal and land plant lineages. The PpPRX family expanded mainly through whole-genome duplications. All duplicated pairs but one were under purifying selection and generally exhibited similar expression profiles. An expanded phylogenetic tree revealed a conserved land plant-wide clade that contained PRXs implicated in stress responses in non-lignifying cells, providing a clue to ancient functions of land plant PRXs. Functional clustering was not observed, suggesting convergent evolution of specific PRX functions (e.g., lignification) in different plant lineages. With its small complement of PRXs, P. patens may be useful for functional characterization of land plant PRXs. Several PpPRXs were proposed for further study, including PpPRX34 and PpPRX39 in the ancient land plant-wide clade.

plant biology↗

bioRxiv2024

Takakia possesses a key marker of embryophyte sporopollenin

The enigmatic moss, Takakia lepidozioides, possesses a particular type III polyketide synthase, ASCL (Anther-Specific Chalcone synthase-Like), that is an identifying marker for genuine sporopollenin in the walls of embryophyte spores and pollen grains. By contrast, a survey of all algae with sequenced genomes confirms that they do not possess ASCL and, therefore, their spore walls are not composed of sporopollenin.

evolutionary biology↗