Identification of a novel microRNA (miRNA) from rice that targets an alternatively spliced transcript of the Nramp6 (Natural resistance‐associated macrophage protein 6) gene involved in pathogen resistance

Abstract

Plants have evolved efficient defence mechanisms to defend themselves from pathogen attack. Although many studies have focused on the transcriptional regulation of defence responses, less is known about the involvement of microRNAs (miRNAs) as post-transcriptional regulators of gene expression in plant immunity. This work investigates miRNAs that are regulated by elicitors from the blast fungus Magnaporthe oryzae in rice (Oryza sativa). Small RNA libraries were constructed from rice tissues and subjected to high-throughput sequencing for the identification of elicitor-responsive miRNAs. Target gene expression was examined by microarray analysis. Transgenic lines were used for the analysis of miRNA functioning in disease resistance. Elicitor treatment is accompanied by dynamic alterations in the expression of a significant number of miRNAs, including new members of annotated miRNAs. Novel miRNAs from rice are proposed. We report a new rice miRNA, osa-miR7695, which negatively regulates an alternatively spliced transcript of OsNramp6 (Natural resistance-associated macrophage protein 6). This novel miRNA experienced natural and domestication selection events during evolution, and its overexpression in rice confers pathogen resistance. This study highlights an miRNA-mediated regulation of OsNramp6 in disease resistance, whilst illustrating the existence of a novel regulatory network that integrates miRNA function and mRNA processing in plant immunity.

MicroRNAs: The Potential Biomarkers in Plant Stress Response

“…In powdery mildew disease of wheat caused by fungus Blumeria graminis f. sp.tritici (Bgt) have showed miRNA differential expression patterns-miR156, miR159, miR164, miR171 and miR396, were found to be down regulated while miR393, miR444 and miR827 were found to be up regulated [28]. Overexpression of Osa-miR7696 was found in rice blast infection [29].…”

Multiple Rice MicroRNAs Are Involved in Immunity against the Blast Fungus Magnaporthe oryzae

“…However, to date, limited studies imply that small RNAs may be involved in rice immunity against the blast fungus M. oryzae. A recent report assayed the accumulation of miRNAs in rice treated by elicitors extracted from blast fungal mycelia (Campo et al, 2013). A new rice miRNA, osa-miR7695, was identified to be involved in rice resistance by negatively regulating the transcript of NATURAL RESISTANCE-ASSOCIATED MACROPHAGE PROTEIN6 (Campo et al, 2013).…”

“…A recent report assayed the accumulation of miRNAs in rice treated by elicitors extracted from blast fungal mycelia (Campo et al, 2013). A new rice miRNA, osa-miR7695, was identified to be involved in rice resistance by negatively regulating the transcript of NATURAL RESISTANCE-ASSOCIATED MACROPHAGE PROTEIN6 (Campo et al, 2013). Currently, miRBase lists over 700 mature miRNA sequences cloned or predicted in rice (http://www.mirbase.org; Kozomara and Griffiths-Jones, 2011).…”

In silico identification of candidate microRNAs and their targets in potato somatic hybrid Solanum tuberosum (+) S. pinnatisectum for late blight resistance

“…Sixth miR3979 gene family b stu-miR1030 (a to g): stu-miR1030a, stu-miR1030b, stu-miR1030c, stu-miR1030d, stu-miR1030e, stu-miR1030f and stu-miR1030g; stu-miR1510 (a and b): stu-miR1510a and stu-miR1510b; stu-miR2673 (a and b): stu-miR2673a and stumiR2673b. implicates to rice root development and resistance to the blast fungus Magnaporthe oryzae in rice (Campo et al, 2013). Importantly, seventh miR5021 family is called MYB transcription factor and is a key factor in regulatory networks controlling development, metabolism and responses to biotic and abiotic stresses (Dubos et al, 2010).…”

“…With the discovery of first miRNAs (lin-4 and let-7) in Caenorhabditis elegans (Olsen et al, 1999), in plants first miRNA was identified in Arabidopsis thaliana in 2002 (Park et al, 2002). Since then with the advent of modern computational tools and conserved nature of mature miRNAs, several miRNAs have been identified across the plant species such as potato (Xie et al, 2011;Yang et al, 2013;Zhang et al, 2013), Solanaceae plants (Kim et al, 2011), Arabidopsis (Liang et al, 2015), rice (Campo et al, 2013), wheat (Akdogan et al, 2015), Brassica juncea (Srivastava et al, 2013), chickpea (Kohli et al, 2014), citrus (Lu et al, 2014) and peach (Luo et al, 2013) to name a few. To date, a total of 24,521 distinct mature hairpin precursor miRNAs across 206 species have been annotated in the miRBase Release 20, an open online repository.…”