Ashton, N. W. | Search bioRxiv

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↗

bioRxiv2023

The curvature of Physcomitrium patens caulonemal filaments in relation to their capacity forphototropic and thigmotropic responses and nutation

Light-grown, whole gametophytic colonies of Physcomitrium (formerly Physcomitrella) patens (Hedw.) Mitt. exhibit a spiral morphology resulting from the strongly coordinated curvature of the population of peripheral caulonemal filaments. The direction of curvature is predominantly clockwise when cultures are illuminated from above and anticlockwise when illuminated from below. In P. patens, side branch initials (SBIs) emerge from caulonemal subapical cells on the outside of the curve. By contrast, the curvature of caulonemata of Funaria hygrometrica is predominantly anticlockwise when colonies are illuminated from above and clockwise when illuminated from below. In F. hygrometrica, SBIs emerge from caulonemal subapical cells on the inside of the curve. We have discounted a role for gravity in these phenomena and discuss several other possible mechanistic explanations. We also document for the first time thigmotropism of protonemata of P. patens. O_TBL View this table: org.highwire.dtl.DTLVardef@9b2d80org.highwire.dtl.DTLVardef@1c83f39org.highwire.dtl.DTLVardef@1aecda3org.highwire.dtl.DTLVardef@13ebd83org.highwire.dtl.DTLVardef@be625_HPS_FORMAT_FIGEXP M_TBL O_FLOATNOBox 1.C_FLOATNO O_TABLECAPTIONGlossary of Terminology C_TABLECAPTION C_TBL

plant biology↗

bioRxiv2023

D-serine- and p-fluorophenylalanine-resistant mutants of Physcomitrium patens are defective in amino acid uptake

Two amino acid analogue-resistant lines of Physcomitrium (formerly Physcomitrella) patens, DSR8 and PFR4, are resistant to a range of D-amino acids and an inhibitory concentration of L-lysine. Both are defective in the uptake of [35S]-L-methionine. Uptake by the wild-type line is pH-dependent (decreasing with raised external proton concentrations) and is depressed by dinitrophenol and by ammonium ions. We discuss the possible involvement of an active proton-general amino acid antiport pump in the plasma membrane.

plant biology↗