Sensor histidine kinases mediate ABA and osmostress signaling in the moss Physcomitrium patens.

To survive fluctuating water availability on land, terrestrial plants must be able to sense water stresses, such as drought and flooding. The plant hormone abscisic acid (ABA) and plant-specific SNF1-related protein kinase 2 (SnRK2) play key roles in plant osmostress responses. We recently reported that, in the moss Physcomitrium patens, ABA and osmostress-dependent SnRK2 activation requires phosphorylation by an upstream RAF-like kinase (ARK).

Archetypal Roles of an Abscisic Acid Receptor in Drought and Sugar Responses in Liverworts.

Abscisic acid (ABA) controls seed dormancy and stomatal closure through binding to the intracellular receptor Pyrabactin resistance1 (Pyr1)/Pyr1-like/regulatory components of ABA receptors (PYR/PYL/RCAR) in angiosperms. Genes encoding PYR/PYL/RCAR are thought to have arisen in the ancestor of embryophytes, but the roles of the genes in nonvascular plants have not been determined. In the liverwort , ABA reduces growth and enhances desiccation tolerance through increasing accumulation of intracellular sugars and various transcripts such as those of ()-like genes.