The MsDHN1‐MsPIP2;1‐MsmMYB module orchestrates the trade‐off between growth and survival of alfalfa in response to drought stress

Abstract

SummaryDehydrins and aquaporins play crucial roles in plant growth and stress responses by acting as protector and controlling water transport across membranes, respectively. MsDHN1 (dehydrin) and MsPIP2;1 (aquaporin) were demonstrated to interact with a membrane‐anchored MYB protein, MsmMYB (as mMYB) in plasma membrane under normal condition. MsDHN1, MsPIP2;1 and MsDHN1‐MsPIP2;1 positively regulated alfalfa tolerance to water deficiency. Water deficiency caused phosphorylation of MsPIP2;1 at Ser 272, which led to release C terminus of mMYB (mMYBΔ83) from plasma membrane and translocate to nucleus, where C terminus of MsDHN1 interacted with mMYBΔ83, and promoted mMYBΔ83 transcriptional activity in response to water deficiency. Overexpression of mMYB and mMYBΔ83 down‐regulated the expression of MsCESA3, but up‐regulated MsCESA7 expression by directly binding to their promoters, and resulted in high drought tolerance in transgenic hairy roots. These results indicate that the MsDHN1‐MsPIP2;1‐MsMYB module serves as a key regulator in alfalfa against drought stress.

How plants sense and respond to osmotic stress

“…The membrane-anchored MYB transcription factor (maMYB), such as the plasma membrane-tethered MYB protein (RhPTM) from rose, and MsmMYB from alfalfa (Medicago sativa L.), are positive regulators of drought tolerance (Zhang et al, 2019;Lv et al, 2023). The two maMYBs interact with the AQPs RhPIP2;1 and MsPIP2;1 and are stored as dormant forms in the plasma membrane under unstressed conditions (Zhang et al, 2019;Lv et al, 2023).…”

“…The membrane-anchored MYB transcription factor (maMYB), such as the plasma membrane-tethered MYB protein (RhPTM) from rose, and MsmMYB from alfalfa (Medicago sativa L.), are positive regulators of drought tolerance (Zhang et al, 2019;Lv et al, 2023). The two maMYBs interact with the AQPs RhPIP2;1 and MsPIP2;1 and are stored as dormant forms in the plasma membrane under unstressed conditions (Zhang et al, 2019;Lv et al, 2023). Drought induces phosphorylation of RhPIP2;1 at Ser273 and MsPIP2;1 at Ser272 (corresponding to Ser280 in AtPIP2;1), which represses maMYB-PIP2;1 interactions and promotes proteolytic processing and the following nuclear translocation of the C-terminus of RhPTM and MsmMYB to regulate associated target genes under drought (Zhang et al, 2019), suggesting a signaling role of RhPIP2;1 besides the role of water channel.…”