RNA-seq-based comparative transcriptome analysis reveals the role of <i>CsPrx73</i> in waterlogging-triggered adventitious root formation in cucumber

Abstract

Abiotic stressors like waterlogging are detrimental to cucumber development and growth. However, comprehension of the highly complex molecular mechanism underlying waterlogging can provide an opportunity to enhance cucumber tolerance under waterlogging stress. We examined the hypocotyl and stage-specific transcriptomes of the waterlogging-tolerant YZ026A and the waterlogging-sensitive YZ106A, which had different adventitious rooting ability under waterlogging. YZ026A performed better under waterlogging stress by altering its antioxidative machinery and demonstrated a greater superoxide ion (O ^2-) scavenging ability. KEGG pathway enrichment analysis showed that a high number of differentially expressed genes (DEGs) were enriched in phenylpropanoid biosynthesis. By pairwise comparison and weighted gene co-expression network analysis analysis, 2616 DEGs were obtained which were categorized into 11 gene co-expression modules. Amongst the 11 modules, black was identified as the common module and yielded a novel key regulatory gene, <i>CsPrx73</i>. Transgenic cucumber plants overexpressing <i>CsPrx73</i> enhance adventitious root (AR) formation under waterlogging conditions and increase reactive oxygen species (ROS) scavenging. Silencing of <i>CsPrx73</i> expression by virus-induced gene silencing adversely affects AR formation under the waterlogging condition. Our results also indicated that <i>CsERF7-3</i>, a waterlogging-responsive ERF transcription factor, can directly bind to the ATCTA-box motif in the <i>CsPrx73</i> promoter to initiate its expression. Overexpression of <i>CsERF7-3</i> enhanced <i>CsPrx73</i> expression and AR formation. On the contrary, <i>CsERF7-3</i>-silenced plants decreased <i>CsPrx73</i> expression and rooting ability. In conclusion , our study demonstrates a novel <i>CsERF7-3</i>-<i>CsPrx73</i> module that allows cucumbers to adapt more efficiently to waterlogging stress by promoting AR production and ROS scavenging.