MicroRNA miR171b Positively Regulates Resistance to Huanglongbing of Citrus

Abstract

Huanglongbing (HLB) is one of the most severe citrus diseases in the world, causing huge economic losses. However, efficient methods of protecting citrus from HLB have not yet been developed. microRNA (miRNA)-mediated regulation of gene expression is a useful tool to control plant diseases, but the miRNAs involved in regulating resistance to HLB have not yet been identified. In this study, we found that miR171b positively regulated resistance to HLB in citrus. Upon infection with HLB bacteria, the bacteria were detected in the second month in the control plants. However, in the miR171b-overexpressing transgenic citrus plants, the bacteria could not be detected until the 24th month. RNA-seq data indicated that multiple pathways, such as photosynthesis, plant–pathogen interaction, the MAPK signaling pathway, etc., might be involved in improving the resistance to HLB in miR171b-overexpressing plants compared with the control. Finally, we determined that miR171b could target SCARECROW-like (SCL) genes to downregulate their expression, which then led to promoted resistance to HLB stress. Collectively, our results demonstrate that miR171b plays a positive regulatory role in resistance to citrus HLB, and provides a new insight into the role of miRNAs in the adaptation of citrus to HLB stress.

Economic and Social Impact of Huanglongbing on the Mexico Citrus Industry: A Review and Future Perspectives

“…Citrus crops have traditionally been cultivated as grafted trees on selected rootstock cultivars to improve tree performance. Although transgenic approaches have made some progress in combating HLB [88], public and regulatory concerns about transgenic plants prevent their widespread commercial acceptance. To address this, it has been proposed to explore the potential of grafting non-transgenic scions onto transgenic rootstocks.…”