The Jasmonic Acid Signaling Pathway Plays an Important Role in Ziziphus jujuba Resistance to Apolygus lucorum

Apolygus lucorum is a polyphagous herbivore that has become a major pest in China. Jujube ( Ziziphus jujuba ) is the main host of A. lucorum. However, better insight into the molecular mechanisms underlying the jujube defense response to A. lucorum is needed. Here, we investigated the resistance of resistant (winter jujube) and sensitive varieties (wild jujube) to A. lucorum. Changes in the transcriptome, jasmonic acid (JA) and salicylic acid (SA) contents and the expression of genes involved in signaling pathways in different jujube varieties were monitored. The preference of A. lucorum for jujube with exogenous SA and methyl jasmonate (MeJA) was examined. Wild jujube showed more resistance and nonselectivity to A. lucorum. RNA-seq analysis showed that 438 and 796 transcripts were differentially expressed in winter jujube and wild jujube leaves infested by A. lucorum . Enrichment analysis showed that more genes in JA pathways were upregulated and more genes in SA pathways were downregulated. A. lucorum increased the JA content and decreased the salicylic acid content. This was confirmed by the alterations of gene expression in the related signaling pathways. MeJA in jujube leaves showed an obvious repellent effect on A. lucorum. Consistently, the contents of jasmonic acid and salicylic acid in winter jujube were lower than those in wild jujube leaves. The present data indicated that A. lucorum infestation of jujube plants induced the JA pathway and suppressed the SA pathway. JA in jujube leaves played an important role in repelling and basic defense against A. lucorum.