RNA-seq analysis of barley (Hordeum vulgare) single mutants in genes encoding barley CBC (HvCBP20, HvCBP80) and a double mutant in both genes encoding barley CBC in response to drought stress applied at the booting stage and subsequent rewatering
Drought poses a significant limitation to crop yield. The nuclear Cap Binding Complex (CBC), made up of CBP20 and CBP80, plays a key role in regulating pre-mRNA splicing and abscisic acid (ABA) signaling. In this study, we examined how mutations in the barley CBC genes (hvcbp20.ab, hvcbp80.b, and the double mutant hvcbp20.ab/hvcbp80.b) affect physiological and transcriptomic responses to drought stress during the booting stage. The mutants exhibited both common and unique mechanisms of drought adaptation. Transcriptome analysis showed that loss of HvCBP80 function markedly suppressed gene transcription and splicing but activated photosynthesis-associated genes, leading to improved photosynthetic performance under both normal and drought conditions. In contrast, HvCBP20 mutation enhanced the expression of ABA-responsive genes and sustained stress-related signaling. On a physiological level, hvcbp20.ab mutants maintained higher stomatal conductance despite having fewer stomata, while hvcbp80.b mutants exhibited reduced conductance under optimal conditions but formed wider stomata during drought. Although these mutations improved certain drought avoidance traits and photosynthetic capacity, they did not translate into gains in yield-related characteristics. Altogether, our results highlight the nuclear CBC as a central modulator of drought responses and recovery in barley, capable of reprogramming gene expression to support enhanced stress resilience. Here we deposit plant samples after drought stress treatment and after rewatering