Transcriptome profiling provides new insights into ABA-mediated genes and pathways in leaves, stems, and roots of mung bean seedlings

Abscisic acid (ABA) is well known as a plant stress hormone. However, ABA-mediated regulation of gene expression profile in plant leaves, stems, and roots under normal conditions has not been fully elucidated. In the present study, foliar spray of 10 μM ABA differentially altered the gene expression levels and profiles of the leaf, root, and stem tissues in mung bean seedlings. An average of 11.3%, 13.8%, and 14.0% of the genes with transcripts per kilobase per million mapped reads (TPM) ≥ 1 were significantly (p ≤ 0.05) regulated by ABA in the leaf, stem, and root tissues, respectively. A total of 690 differentially expressed genes (DEGs) were detected, of which 232, 259, and 227 DEGs were identified in the leaves, stems, and roots, respectively. A majority of the DEGs in leaves and roots were upregulated at 1 and 9 days after ABA application, while those in stems were downregulated. Of the significantly (FDR < 0.05) enriched KEGG pathways, MAPK signaling, plant hormone signal transduction, and plant-pathogen interaction shared many common genes, suggesting that ABA fundamentally triggered the cellular signal transduction. All the genes involved in phenylpropanoid biosynthesis and flavonoid biosynthesis were upregulated in leaves, implying the activation of these metabolic processes. Furthermore, apart from the signaling-related DEGs, most of the DEGs were oxidoreductases-, transporters-, and pathogen-resistant proteins-coding genes, which are related to cellular oxidative response and abiotic and biotic stress response, indicating the regulation of ABA on stress-responsive genes. The results might be conducive to understand exogenous ABA-mediated differential regulation of gene expression in plant leaves, stems, and roots, especially in leguminous plants.