# The long non-coding RNA MSTRG.32189-PcmiR399b-PcUBC24 module regulates phosphate accumulation and disease resistance to Botryosphaeria dothidea in pear

## TL;DR

This study identifies a long non-coding RNA module that helps pears resist a harmful disease by regulating phosphate levels and immune responses.

## Contribution

The study reveals a novel lncRNA-miRNA-target gene module involved in pear disease resistance and phosphate regulation.

## Key findings

- MSTRG.32189 inhibits PcmiR399b cleavage of PcUBC24, affecting phosphate levels and disease resistance.
- Overexpression of MSTRG.32189 or PcmiR399b alters pear callus resistance to Botryosphaeria dothidea.
- The MSTRG.32189-PcmiR399b-PcUBC24 module regulates ROS levels and disease resistance genes.

## Abstract

Pear ring rot disease (Botryosphaeria dothidea) 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 B. dothidea. It identified 3555 lncRNAs, of which 286 were significantly differentially expressed. GO and KEGG analyses showed that cis- and trans-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 B. dothidea infection, and was confirmed to inhibit the cleavage effect of PcmiR399b on PcUBC24. OE-MSTRG.32189 transgenic Arabidopsis exhibited lower Pi content and weaker disease resistance to Botrytis cinerea 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 PcUBC24 further clarified that PcUBC24 negatively regulates Pi content and disease resistance to B. dothidea infection. Furthermore, the ROS levels and expressions of disease resistance pathway-related genes were regulated by the MSTRG.32189-PcmiR399b-PcUBC24 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-PcUBC24 module regulates phosphate accumulation and disease resistance to B. dothidea infection in pear.