CIP elicitors on the defense response of A. macrocephala and its related gene expression analysis

Abstract Plant-derived elicitor is a new type of plant vaccine developed in the contemporary era, and it has safe and broad application prospects in organic agriculture. Research on defense mechanisms triggered by elicitor has become a hot topic in recent years. The Chrysanthemum indicum polysaccharide (CIP) obtained by separation and purification from Chrysanthemum indicum was used as an elicitor in this work. This elicitor has been shown to be effective in Atractylodes macrocephala Koidz (A. macrocephala) against Sclerotium rolfsii sacc (S. rolfsii) infection and soil-borne diseases. However, the mechanism of induced disease resistance has not been elucidated. In this research, we study the CIP-induced A. macrocephala defense response from the level of signal molecules and the defensive enzyme gene expression. Several defense responses to CIP treatment have been found in A. macrocephala, including early hydrogen peroxide (H2O2) production, accumulation of salicylic acid (SA) and increased phytoalexin (PA) content. In addition, CIP significantly increased the activity of related defense enzymes in A. macrocephala. RT-qPCR analysis showed that defense-related genes such as polyphenol oxidase (PPO) and phenylalanine ammonia lyase (PAL) were up-regulated after CIP treatment. To obtain the sequence of the defense enzyme gene, we are the first to provide a public and comprehensive A. macrocephala database by transcriptome sequencing. These results together demonstrate that CIP triggers defense responses in A. macrocephala. Our research not only provides further research on immune mechanism between plant and elicitor, but also sheds new light on strategy for biocontrol in the future.