Moderate Cold Stress Enhance Drought Resistance through CCA1 via -an ABA- independent Pathway

In nature, plants frequently encounter concurrent stresses, particularly the simultaneous occurrence of cold and drought stress poses a challenge to plants in middle and high latitudes. However, the molecular mechanisms underlying the plants response to this double-stress scenario remain unclear. Although some responses suggest that drought stress can improve cold resistance in plants, through ABA signaling pathways. In our study, we discovered that moderate low temperature treatment significantly enhanced Arabidopsis drought tolerance. Low temperature rapidly triggers the transcription factor CCA1, a prototypical response to cold stress, which inturn directly regulates the expression of OST1 and P5CS1 by binding to their promoters. This leads to the premature closure of stomata and accumulation of proline through a non-ABA-dependent pathway even before plants experience drought stress, ultimately improving plant resistance against drought and cold. Moreover, this mechanism is conserved across plant species, and the synergistic resistance mechanism enables perennial plants to survive winter conditions and annual plants to withstand multi-stresses.