Cuticular wax modification by Epichloë endophyte in Achnatherum inebrians under Blumeria graminis infection

Achnatherum inebrians is a perennial plant belonging to the Poaceae, subfamily Pooideae, which often forms a symbiosis with fungal endophytes of the genus Epichloë. In this study, E. gansuensis-infected (E+) and E. gansuensis-free (E−) A. inebrians were inoculated with Blumeria graminis (pathogen-inoculated, P+; non-inoculated, P−) under greenhouse conditions. Gas chromatography-mass spectrometry (GC-MS) and transcriptome sequencing were combined to characterize the response of the leaf cuticular wax of A. inebrians plants with and without the Epichloë endophyte to B. graminis stress. The present results revealed that the predominant components of the cuticular wax of A. inebrians leaves under the Epichloë endophyte and B. graminis treatments were hydrocarbons, esters, and fatty acids. The total cuticular wax and ester contents of the E+ and E− A. inebrians leaves significantly (p < 0.05) increased under the B. graminis treatment, but the total cuticular wax and ester contents of the E+ leaves were greater than those of the E− plants. Through transcriptome analysis, 15 genes that were differentially expressed and related to cuticular wax biosynthesis were identified, including fadD, fadF, TER, SSI2, BiP, CER1, FAR, and KCS.