Two trehalase isoforms, produced from a single transcript, regulate drought stress tolerance in Arabidopsis thaliana

Key message Alternative translation initiation of the unique Arabidopsis trehalase gene allows for the production of two isoforms with different subcellular localization, providing enzyme access to both intra- and extra-cellular trehalose. The trehalose-hydrolyzing enzyme trehalase mediates drought stress tolerance in Arabidopsis thaliana by controlling ABA-induced stomatal closure. We now report the existence of two trehalase isoforms, produced from a single transcript by alternative translation initiation. The longer full-length N-glycosylated isoform (AtTRE1L) localizes in the plasma membrane with the catalytic domain in the apoplast. The shorter isoform (AtTRE1S) lacks the transmembrane domain and localizes in the cytoplasm and nucleus. The two isoforms can physically interact and this interaction affects localization of AtTRE1S. Consistent with their role in plant drought stress tolerance, both isoforms are activated by AtCPK10, a stress-induced calcium-dependent guard cell protein kinase. Transgenic plants expressing either isoform indicate that both can mediate ABA-induced stomatal closure in response to drought stress but that the short (cytoplasmic/nuclear) isoform, enriched in those conditions, is significantly more effective.

Automated summary

This study reports the discovery of two isoforms of trehalase in Arabidopsis that have different subcellular localization and are involved in the regulation of drought stress tolerance. These isoforms can interact with each other and their activation is dependent on a stress-induced calcium-dependent protein kinase. Both isoforms can mediate ABA-induced stomatal closure, but the cytoplasmic/nuclear isoform is more effective in drought conditions.