Transcriptomic Insights into Abies koreana Drought Tolerance Conferred by Aureobasidium pullulans AK10.

The conservation of the endangered Korean fir, Abies koreana, is of critical ecological importance. In our previous study, a yeast-like fungus identified as Aureobasidium pullulans AK10, was isolated and shown to enhance drought tolerance in A. koreana seedlings. In this study, the effectiveness of Au. pullulans AK10 treatment in enhancing drought tolerance in A. koreana was confirmed. Furthermore, using transcriptome analysis, we compared A. koreana seedlings treated with Au. pullulans AK10 to untreated controls under drought conditions to elucidate the molecular responses involved in increased drought tolerance. Our findings revealed a predominance of downregulated genes in the treated seedlings, suggesting a strategic reallocation of resources to enhance stress defense. Further exploration of enriched Kyoto Encyclopedia of Genes and Genomes pathways and protein-protein interaction networks revealed significant alterations in functional systems known to fortify drought tolerance, including the terpenoid backbone biosynthesis, calcium signaling pathway, pyruvate metabolism, brassinosteroid biosynthesis, and, crucially, flavonoid biosynthesis, renowned for enhancing plant drought resistance. These findings deepen our comprehension of how AK10 biostimulation enhances the resilience of A. koreana to drought stress, marking a substantial advancement in the effort to conserve this endangered tree species through environmentally sustainable treatment.