The JASMONATE ZIM-domain-OPEN STOMATA1 cascade integrates jasmonic acid and abscisic acid signaling to regulate drought tolerance by mediating stomatal closure in poplar.

Drought, which directly affected the yield of crops and trees, is a natural disaster with a profound impact on the economy. Improved water-use efficiency (WUE) and drought tolerance are currently known to be the relatively effective strategies to alleviate drought stress. OPEN STOMATA1 (OST1), the core of ABA signal, can further provide WUE by regulating the stomata closure and photosynthesis. Methyl jasmonate (MeJA) and abscisic acid (ABA) crosstalk is supposed to be involved in response to drought stress. However, detailed molecular mechanism is seriously insufficient. Here, Populus euphratica, which is naturally growing in arid and semiarid regions, was selected as the material to perform yeast mating using PeOST1 as a bait. We report that a nucleus-localized factor PeJAZ2 participated in MeJA signaling interacts with PeOST1. Overexpression of PeJAZ2 in poplar remarkably increased water deficit tolerance and WUE both in severe- and mild- drought stresses by regulating ABA signaling rather than ABA synthesis. Furthermore, PeJAZ2 overexpressing lines were shown to promote the ABA-induced stomatal closure and the hydrogen peroxide (H2O2) production. Collectively, these convincing evidences establish a mechanism that PeJAZ2 act as a positive regulator in response to drought stress via ABA-induced stomatal closure caused by H2O2 production, and provide a new sight for interpreting the cross-talk of ABA and JA signaling in regulating WUE and drought stress, to provide a basis for the drought tolerance mechanism of P. euphratica.