Transcriptomic Determination of the Core Genes Regulating the Growth and Physiological Traits of Quercus mongolica Fisch. ex Ledeb

Abstract

Quercus mongolica is a multipurpose forest species of high economic value that also plays an important role in the maintenance and protection of its environment. Consistent with the wide geographical distribution of Q. mongolica, differences in the growth and physiological traits of populations of different provenances have been identified. In this study, the molecular basis for these differences was investigated by examining the growth, physiological traits, and gene expression of Q. mongolica seedlings from six provenances in northern China. The results showed that there were significant differences in growth and physiological traits, except for the ground diameter (p < 0.05), and identified abscisic acid (ABA), indole-3-acetic acid (IAA), and soluble sugar contents as important physiological traits that distinguish Q. mongolica of different provenances. The transcriptome analysis showed that the largest difference in the total number of differentially expressed genes (DEGs) was between trees from Jilin and Shandong (6918), and the smallest difference was between trees from Heilongjiang and Liaoning (1325). The DEGs were concentrated mainly in the Gene Ontology entries of metabolic process, catalytic activity, and cell, and in the Kyoto Encyclopedia of Genes and Genomes metabolic pathways of carbohydrate metabolism, biosynthesis of other secondary metabolites, signal transduction, and environmental adaptation. These assignments indicated that Q. mongolica populations of different provenances adapt to changes in climate and environment by regulating important physiological, biochemical, and metabolic processes. A weighted gene co-expression network analysis revealed highly significant correlations of the darkmagenta, grey60, turquoise, and plum1 modules with ABA content, IAA content, soluble sugar content, and soluble protein content, respectively. The co-expression network also indicated key roles for genes related to the stress response (SDH, WAK5, APA1), metabolic processes (UGT76A2, HTH, At5g42100, PEX11C), signal transduction (INPS1, HSD1), and chloroplast biosynthesis (CAB13, PTAC16, PNSB5). Functional annotation of these core genes implies that Q. mongolica can adapt to different environments by regulating photosynthesis, plant hormone signal transduction, the stress response, and other key physiological and biochemical processes. Our results provide insight into the adaptability of plants to different environments.