Drought is a yield-limiting factor in the face of climate change, underscoring the need to uncover key regulators that will allow for a better understanding of plant resistance mechanisms. Phytohormone priming represents a promising strategy, and abscisic acid (ABA) act as phytohormone coordinating stress responses. Mutations in the mRNA cap-binding complex (CBC) increase ABA sensitivity and enhance drought tolerance, but it is unclear whether CBC modulates ABA-mediated priming. To test how CBC affects ABA priming in barley we used hvcbp20.ab, hvcbp80.b and unique hvcbp20.ab/hvcbp80.b double mutants obtained using TILLING on "Sebastian" (WT) background. We applied ABA during tillering and imposed drought during pre-flowering stage, followed by rewatering. We integrated physiological parameters with transcriptome profiling, including alternative splicing analyses. ABA priming did not consistently improve drought performance in CBC mutants, but induced distinct, subunit-dependent drought responses. Integration of physiological parameters with transcriptome profiling indicates that CBC is an important factor of how ABA-priming signals are integrated and translated into downstream responses under drought stress. In particular, CBC-dependent differences in photosynthetic efficiency and drought-related gene expression and alternative splicing suggest coordinated transcriptional and post-transcriptional control of priming outcomes. Overall, these findings indicates CBC as a key modulator of ABA-priming signal integration and drought reprogramming in barley. This work was supported by the National Science Center, Poland project SONATA BIS10 ‘(QUEST) Quest for climate-smart barley–the multilayered genomic study of CBC function in ABA signaling’ (2020/38/E/NZ9/00346).
