Fungal diseases such as anthracnose substantially affect the growth of tea (Camellia sinensis) plants. Identifying resistance genes and elucidating the mechanisms of resistance is crucial for breeding anthracnose-resistant tea varieties. Small RNA transcriptome sequencing was used to analyze differentially expressed microRNAs (miRNAs) and their target genes in tea leaves at 6 d post-inoculation with Colletotrichum camelliae, combined with functional enrichment analysis. A novel regulatory axis was delineated - comprising long noncoding RNA Cslnc924, CsmiR390a, CsTAS3 (trans-acting siRNA), CsARF2s (auxin response factors), and CsOPR2 (12-oxo-phytodienoic acid reductase) - that plays a novel role for this axis in anthracnose resistance in tea plants. Mechanistically, the 257-511 bp region of Cslnc924 binds to the promoter region (-825 to -1053 bp) of CsmiR390a, thereby activating its transcription. This upregulation of CsmiR390a positively modulated the CsmiR390a-CsTAS3-CsARF2 module, leading to the reduced expression of ARF2s (ARF2.1 and ARF2.2). Consequently, the suppression of CsOPR2-1 by ARF2s was alleviated, thereby enhancing anthracnose resistance in tea plants. This study reveals the regulatory role of the CsmiR390a-CsTAS3-CsARF2s module in tea-anthracnose resistance and deepens the understanding of lncRNA-miRNA-mRNA regulatory mechanisms in tea plant defense against fungal pathogens.
Jiang et al. (Wed,) studied this question.