The long non-coding RNA MSTRG.32189-PcmiR399b- module regulates phosphate accumulation and disease resistance to in pear.

Pear ring rot disease () is a significant threat to the healthy development of the pear industry. Recent research has identified the functional role of long non-coding RNAs (lncRNAs) in various biological processes of plants. The role of lncRNAs in the pear defense response remains unknown. In this study, transcriptome sequencing was used to analyze lncRNAs in pear stem infected with . It identified 3555 lncRNAs, of which 286 were significantly differentially expressed. GO and KEGG analyses showed that - and -regulated target genes were enriched in multiple disease resistance-related pathways. More specifically, MSTRG.32189, predicted as an endogenous target mimic (eTM), was significantly down-regulated in response to infection, and was confirmed to inhibit the cleavage effect of PcmiR399b on OE-MSTRG.32189 transgenic exhibited lower Pi content and weaker disease resistance to compared with wild type. In pear callus, overexpression of MSTRG.32189 negatively regulated PcmiR399b, which decreased Pi content and reduced disease resistance. Overexpressing PcmiR399b in pear callus exhibited the opposite effects compared with OE-MSTRG.32189. Overexpression and knockout of further clarified that negatively regulates Pi content and disease resistance to infection. Furthermore, the ROS levels and expressions of disease resistance pathway-related genes were regulated by the MSTRG.32189-PcmiR399b- module in transgenic pear callus, which contributed to disease resistance. Overall, our results demonstrated the role of lncRNAs in the pear defense response, revealing that the MSTRG.32189-PcmiR399b- module regulates phosphate accumulation and disease resistance to infection in pear.