Rebuilding core abscisic acid signaling pathways of Arabidopsis in yeast

Abstract

The phytohormone abscisic acid (ABA) regulates plant responses to abiotic stress, such as drought and high osmotic conditions. The multitude of functionally redundant components involved in ABA signaling poses a major challenge for elucidating individual contributions to the response selectivity and sensitivity of the pathway. Here, we reconstructed single ABA signaling pathways in yeast for combinatorial analysis of ABA receptors and coreceptors, downstream‐acting SnRK2 protein kinases, and transcription factors. The analysis shows that some ABA receptors stimulate the pathway even in the absence of ABA and that SnRK2s are major determinants of ABA responsiveness by differing in the ligand‐dependent control. Five SnRK2s, including SnRK2.4 known to be active under osmotic stress in plants, activated ABA‐responsive transcription factors and were regulated by ABA receptor complexes in yeast. In the plant tissue, SnRK2.4 and ABA receptors competed for coreceptor interaction in an ABA‐dependent manner consistent with a tight integration of SnRK2.4 into the ABA signaling pathway. The study establishes the suitability of the yeast system for the dissection of core signaling cascades and opens up future avenues of research on ligand‐receptor regulation.

MAP3Kinase-dependent SnRK2-kinase activation is required for abscisic acid signal transduction and rapid osmotic stress response

“…However, the upstream osmotic stress signalling mechanisms remain incompletely understood. Recent studies suggest that PP2Cs involved in ABA signalling dephosphorylate SnRK2.4 46–48 . The M3K ARK is required for osmotic stress tolerance in Physcomitrella 28,42 .…”

A Synthetic Approach Allows Rapid Characterization of the Maize Nuclear Auxin Response Circuit

“…Thus, our functional annotation and characterization of maize auxin signaling modules is in agreement with the few existing genetic and biochemical studies on maize Aux/IAAs and REL2 and extends functional characterization to many previously uninvestigated maize auxin signaling components for which there are no known mutants. The recent recapitulation of the Arabidopsis abscisic acid hormone signaling pathway in yeast underscores the feasibility of performing similar functional annotation efforts for putative orthologous proteins across many plant signaling pathways (Ruschhaupt et al, 2019). Admittedly these minimal signaling modules do not encompass the full complexity present in vivo, although the ARC Sc has been used to investigate competition between corepressors and the functional role of IAA and ARF PB1 domain oligomerization (Pierre-Jerome et al, 2014 as well as ARF promoter architecture preferences (Lanctot et al, 2020).…”

Toward a better understanding of signaling networks in plants: yeast has the power!

“…The present article reports on a system that enables analyses of large numbers of signaling component permutations and will undoubtedly trigger new studies in plants, for example, on the direct ABA signal transduction roles of the newly identified SnRK2 kinase candidates found in this study (Ruschhaupt et al , ). Further work will be needed to investigate which new models derived from reconstitution of the ABA signal transduction pathway in yeast reflect signaling mechanisms present in plants.…”