HOS15: A missing link that fine-tunes ABA signaling and drought tolerance inArabidopsis

摘要

Among the phytohormones, abscisic acid (ABA) specifically regulates plant adaptation to osmoticstresses, such as drought and high salinity, by controlling the internal water status in plants.A significant accumulation of ABA occurs in response to conditions of water deficit; this is followed bya sophisticated signaling relay, known as the ABA signaling pathway, which decreases the rate oftranspiration through stomatal closure, thereby suppressing photosynthetic activity. Snf1-related kinases(SnRK2s) are the major components regulating the ABA signaling pathway. Of these, SnRK2.6 (OST1) andSnRK2.3 are negatively regulated by HOS15 (HIGH EXPRESSION OF OSMOTICALLY RESPONSIVE15), in anABA-dependent manner, to cease the signaling relay. HOS15 is a WD40-repeat protein that regulatesseveral physiological processes, including plant growth and development, freezing stress responses, andABA signaling. Here, we provide a brief overview of the functional importance of HOS15 in theregulation of ABA signaling and drought stress.