MicroR828 regulates lignin and H2O2 accumulation in sweet potato on wounding

• Published in: The New phytologist Vol. 196; no. 2; pp. 427 - 440
• Main Authors: Lin, Jeng‐Shane, Lin, Chih‐Ching, Lin, Hsin‐Hung, Chen, Yu‐Chi, Jeng, Shih‐Tong
• Format: Journal Article
• Language: English
• Published: England New Phytologist Trust 01.10.2012; Wiley Subscription Services, Inc
• Subjects: Accumulation; Acetates - pharmacology; Agrobacterium - drug effects; Agrobacterium - metabolism; Antioxidants - metabolism; Base Sequence; Calcium - metabolism; Cleavage; Cloning; Complementary DNA; Cyclic ADP-Ribose - metabolism; Cyclic GMP; Cyclic GMP - metabolism; Cyclopentanes - pharmacology; Defence mechanisms; DNA; Ethylenes - pharmacology; Gene expression; Gene Expression Profiling; Gene expression regulation; Gene Expression Regulation, Plant - drug effects; Genes; Guanosine; Hydrogen peroxide; hydrogen peroxide (H2O2); Hydrogen Peroxide - metabolism; Infiltration; Ipomoea batatas; Ipomoea batatas - drug effects; Ipomoea batatas - enzymology; Ipomoea batatas - genetics; Ipomoea batatas - metabolism; Leaves; Lignin; Lignin - metabolism; Messenger RNA; Methyl jasmonate; MicroRNA; MicroRNAs - chemistry; MicroRNAs - genetics; MicroRNAs - metabolism; miR828; miRNA; Molecular Sequence Data; Niacinamide - pharmacology; Nitric oxide; Nitric Oxide - metabolism; Okadaic Acid - pharmacology; Oxylipins - pharmacology; Phosphoprotein Phosphatases - metabolism; Plant Proteins - genetics; Plant Proteins - metabolism; Plants; Plants, Genetically Modified; Potatoes; Propanols - metabolism; Protein Kinases - metabolism; RNA; RNA, Messenger - genetics; RNA, Messenger - metabolism; Small interfering RNA; Staurosporine - pharmacology; Stress, Mechanical; sweet potato (Ipomoea batatas); Sweet potatoes; Transcription; Wounding
• ISSN: 0028-646X; 1469-8137
• DOI: 10.1111/j.1469-8137.2012.04277.x

MicroRNAs (miRNAs) are small noncoding RNAs which post-transcriptionally regulate gene expression by directing mRNA cleavage or translational inhibition. miRNAs play multiple roles in the growth, development and stress responses in plants. However, little is known of the wounding-responsive miRNAs and their regulation. Here, we investigated the expression patterns of microR828 (miR828) on wounding in sweet potato (Ipomoea batatas cv Tainung 57). The expression of miR828 was only detected in leaves, and was induced by wounding rather than by ethylene, hydrogen peroxide (H2O2), methyl jasmonate or nitric oxide (NO). Moreover, cyclic guanosine monophosphate (cGMP) was necessary for miR828 accumulation in leaves on wounding. Two miR828 target candidates, named IbMYB and IbTLD, were obtained by cDNA cloning, and their mRNA cleavage caused by miR828 was confirmed by cleavage site mapping, agro-infiltration and transgenics studies. The reduction in IbMYB and IbTLD expression coincided with the induction of miR828, demonstrating thatIbMYB and IbTLD might be miR828 targets. Furthermore, transgenic sweet potato overexpressing miR828 precursor affected lignin and H2O2 contents. These results showed that cGMP could regulate wounding-responsive miR828, which repressed the expression of IbMYB and IbTLD. Subsequently, lignin and H2O2 were accumulated to participate in defense mechanisms.