The role of ABA in better adaptation to drought of Cap Binding Complex (CBC) barley mutants
Hubert Matkowski, Anna Collin, Agata Daszkowska-Golec
Plant Genetics and Functional Genomics Lab, Institute of Biology, Biotechnology and Environmental Protection, Faculty of Natural Sciences, University of Silesia in Katowice, Jagiellonska 28, 40-032 Katowice, Poland

Every year, the escalating severity of drought episodes poses a notable threat to global crop. Addressing plant vulnerability to drought involves exploring key regulators of drought response and developing more resilient varieties with mutations in crucial genes that positively influence adaptation to drought. In our experiment, we investigated the impact of abscisic acid (ABA), a crucial regulator of drought response, and barley mutants (H. vulgare sp. Sebastian) in genes encoding the CBC complex which is integral to ABA-related signaling. Previous research indicated that mutations in these genes enhance plant resistance to drought stress. Utilizing the TILLING method, we identified mutants (hvcbp20.ab and hvcbp80.b) carrying changes in both CBC complex subunit-encoding genes. Additionally, we created a double mutant, hvcbp20.ab/hvcbp80.b. The experiment involved subjecting plants to drought stress, ABA treatment, and a combination of ABA followed by drought. Physiological and morphological analyses revealed that mutations in CBC complex genes significantly affected photosynthetic parameters, with ABA application enhancing this process. Global transcriptome analysis identified crucial genes and biological processes dependent on ABA and drought stress in the mutants. In summary, our research demonstrates that mutations in CBC complex genes confer protection to plants against drought stress, and the external application of ABA further improves this resilience.