High quality MAGs from lignocellulose-impacted environments elucidate metabolism and evolutionary mechanisms.

The archaeal class is widely and abundantly distributed in anoxic habitats. Metagenomic studies have suggested that they are mixotrophic, capable of CO fixation and heterotrophic growth, and involved in acetogenesis and lignin degradation. We analyzed 35 metagenome-assembled genomes (MAGs), including the first complete circularized MAG (cMAG) of the Bathy-6 subgroup, from the metagenomes of three full-scale pulp and paper mill anaerobic digesters and three laboratory methanogenic enrichment cultures maintained on pre-treated poplar.

Resolving the contrasting leaf hydraulic adaptation of C and C grasses.

Grasses are exceptionally productive, yet their hydraulic adaptation is paradoxical. Among C grasses, a high photosynthetic rate (A) may depend on higher vein density (D) and hydraulic conductance (K). However, the higher D of C grasses suggests a hydraulic surplus, given their reduced need for high K resulting from lower stomatal conductance (g).

C photosynthesis and hydraulics in grasses.

The anatomical reorganization required for C photosynthesis should also impact plant hydraulics. Most C plants possess large bundle sheath cells and high vein density, which should also lead to higher leaf capacitance and hydraulic conductance (K). Paradoxically, the C pathway reduces water demand and increases water use efficiency, creating a potential mismatch between supply capacity and demand in C plant water relations.