Transcriptome analysis of Gardenia jasminoides Ellis in response to Botryosphaeria dothidea

Botryosphaeria dothidea (B. dothidea) is a pathogenic fungus that causes brown spot disease of Gardenia jasminoides Ellis(GE). Brown spot is a serious disease that affects the growth of plants and easy to be infected in GE. In order to reveal the leaf-mediated resistance mechanism to the B. dothidea. Firstly, we used scanning electron microscope(SEM) and transmission electron microscope (TEM) to observe the ultrastructure of normal leaves and infested leaves via B. dothidea. SEM showed that B. dothidea invaded the leaves mainly by lysing the epidermis. TEM shows that the physiological structure of GE leaves is severely affected by the infestation of B. dothidea, including the deformation of chloroplasts, the dissolution of chloroplast membranes, the distortion or even rupture of cell membranes, and the existence of plasma wall separation. Subsequently, we used RNA-Seq to elucidate the dynamic transcriptome of GE leaves after 0 h, 12 h, 1 d, 2 d and 3 d infection with B. dothidea. Differentially expressed genes(DEGs) were found for different times of infestation, and the KEGG pathway was used to enrich for the pathways with more genes involved and related to defence, including phenylpropanoid biosynthesis, plant hormone signal transduction, starch and sucrose metabolism pathways. Finally, the STRING database was applied to analyse the protein interaction network for each of the three pathways, and Cytoscape was used to visualise the network and obtain the key genes in the interaction network based on the connectivity of each node in the network. Namely, the key genes for three pathway were COMT1, AUX1, and SUS3. In brief, we used transcriptomics to analyse the mechanism of infestation of GE in response to the causal agent of brown spot disease, B. dothidea. and inferred that COMT1, AUX1 and SUS3 play an important role in the resistance of GE in response to B. dothidea. These results provide new insights into leaf-mediated stress and resistance of GE to diseases.