Arabidopsis MHP1, a homologue of yeast Mpo1, is involved in ABA signaling

Sphingolipids and their intermediates play multiple roles in biological processes. The sphingoid long-chain base component of sphingolipids has emerged as a participant in the regulation of plant biotic and abiotic stress responses. The phytohormone abscisic acid (ABA) regulates many stress responses in plants for environmental adaptation. However, the relationship between the sphingoid bases and ABA is undetermined. In this study, mhp1-1 (the yeast (M) under bar po1 (h) under bar omolog in (p) under bar lants) was isolated through a sodium chloride (NaCl)-sensitivity screen of Arabidopsis transfer DNA (T-DNA) insertion mutants. mhp1-1 was hypersensitivity to salt/osmotic stress and ABA. MHP1 encodes a protein with a domain of unknown function 962 (DUF962). Endoplasmic reticulum-localized MHP1 was found to interact with ABI1. MHP1, a homolog of yeast dioxygenase Mpo1, rescued the growth arrest of mpo1 Delta cells caused by ER stress, suggesting functional homology of MHP1 to Mpo1. Overall, MHP1 plays important roles in response to ABA.

Automated summary

The study identified the important role of MHP1 in plant stress responses to salt/osmotic stress and ABA through screening of Arabidopsis T-DNA insertion mutants. The MHP1 protein interacts with ABI1 and exhibits functional homology to the yeast dioxygenase Mpo1 in responding to ER stress. Overall, MHP1 plays a crucial role in ABA-mediated stress responses in plants.