Abstract
MiRNAs play diverse roles in plant development and defense responses by binding to their mRNA targets based on sequence complementarity. Here, we investigated a wound-related miR408 and its target genes in sweet potato (Ipomoea batatas) by small RNA deep sequencing and transcriptome analysis. The expression patterns of miR408 and the miR408 precursor were significantly repressed by wounding and jasmonate (JA). In contrast, expression of the putative target genes IbKCS (3-ketoacyl-CoA synthase 4), IbPCL (plantacyanin), and IbGAUT (galacturonosyltransferase 7-like) of miR408 was increased following wounding, whereas only IbKCS was increased after JA treatment. Target cleavage site mapping and Agrobacterium-mediated transient assay demonstrated that IbKCS, IbPCL, and IbGAUT were the targets of miR408. The expression of miR408 target genes was repressed in transgenic sweet potatoes overexpressing miR408. These data indicated a relationship between miR408 and its target genes. Notably, miR408-overexpressing plants showed a semi-dwarf phenotype and attenuated resistance to insect feeding, while transgenic plants overexpressing IbKCS exhibited more insect resistance than plants overexpressing only the empty vector. Collectively, sweet potato reduces the abundance of miR408 upon wounding to elevate the expression of IbKCS, IbPCL, and IbGAUT. The expression of IbKCS enhances the defense system against herbivore wounding.
Highlights
Plants possess complex signaling systems to survive biotic and abiotic stressors (Wong and Shimamoto, 2009)
The miR408:miR408* ratio was ~100:1 based on the small RNA deep sequencing data.To isolate the miR408 precursor in sweet potato, the sequence of miR408 was searched against a sweet potato transcriptomic database (Supplementary Table S4).A transcriptome contig perfectly matched with the sequence of miR408 was considered to be pre408
These results strongly proved the presence of miR408 in sweet potato
Summary
Plants possess complex signaling systems to survive biotic and abiotic stressors (Wong and Shimamoto, 2009). Plants have evolved complex defense systems against wounding. Responses to damage are local, systemic, or both (León et al, 2001). Wounding signals, including jasmonate (JA), ethylene, Ca2+ influx, nitric oxide, and H2O2, can regulate wounding-responsive genes to function in defense-related processes (Pozo et al, 2008;Wasternack and Hause, 2013). In response to a wounding signal from herbivory, plants activate the expression of proteinase inhibitor and lectin genes, which impair the activity of insect digestive enzymes to decrease the damage by herbivory (Howe, 2004; Chen et al, 2008; Chen et al, 2016b). Several factors, including lignin, pectin, suberin, and waxes, are stimulated in wounded tissue to heal the tissue or to form a physical barrier to prevent
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
