Raquel Salvador-Guirao1, Patricia Baldrich1,2, Shiho Tomiyama3, Yue-Ie Hsing4, Kazunori Okada3, Blanca San Segundo1,5. 1. Centre for Research in Agricultural Genomics (CRAG) CSIC-IRTA-UAB-UB, Campus Universitat Autònoma de Barcelona (UAB), Bellaterra (Cerdanyola del Vallés), Barcelona, Spain. 2. Donald Danforth Plant Science Center, St Louis, MO, USA. 3. Biotechnology Research Center, The University of Tokyo, Tokyo, Japan. 4. Institute of Plant and Microbial Biology, Academia Sinica, Taipei, Taiwan. 5. Consejo Superior de Investigaciones Científicas (CSIC), Barcelona, Spain.
Abstract
Background and Aims: MicroRNAs (miRNAs) are small non-coding RNAs that act as post-transcriptional regulators of gene expression via sequence-specific cleavage or translational repression of target transcripts. They are transcribed as long single-stranded RNA precursors with unique stem-loop structures that are processed by a DICER-Like (DCL) ribonuclease, typically DCL1, to produce mature miRNAs. Although a plethora of miRNAs have been found to be regulated by pathogen infection in plants, the biological function of most miRNAs remains largely unknown. Here, the contribution of OsDCL1 to rice immunity was investigated. Methods: Activation-tagged Osdcl1a (Osdcl1a-Ac) rice mutants were examined for resistance to pathogen infection. mRNA and small RNA deep sequencing, quantitative real-time PCR (RT-qPCR) and stem-loop reverse tanscripion-PCR (RT-PCR) were used to examine DCL1a-mediated alterations in the rice transcriptome. Rice diterpene phytoalexins were quantified by liquid chromatography-tandem mass spectrometry (LC-MSMS). Accumulation of O2·- was determined by nitroblue tetrazolium (NBT) staining. Key Results: dcl1a-Ac mutants exhibit enhanced susceptibility to infection by fungal pathogens which was associated with a weaker induction of defence gene expression. Comparison of the mRNA and miRNA transcriptomes of dcl1a-Ac and wild-type plants revealed misregulation of genes involved in detoxification of reactive oxygen species. Consequently, dcl1a-Ac plants accumulated O2·- in their leaves and were more sensitive to methyl viologen-induced oxidative stress. Furthermore, dcl1a-Ac plants showed downregulation of diterpenoid phytoalexin biosynthetic genes, these genes also being weakly induced during pathogen infection. Upon pathogen challenge, dcl1a-Ac plants failed to accumulate major diterpenoid phytoalexins. OsDCL1a activation resulted in marked alterations in the rice miRNAome, including both upregulation and downregulation of miRNAs. Conclusions: OsDCL1a activation enhances susceptibility to infection by fungal pathogens in rice. Activation of OsDCL1a represses the pathogen-inducible host defence response and negatively regulates diterpenoid phytoalexin production. These findings provide a basis to understand the molecular mechanisms through which OsDCL1a mediates rice immunity.
Background and Aims: MicroRNAs (miRNAs) are small non-coding RNAs that act as post-transcriptional regulators of gene expression via sequence-specific cleavage or translational repression of target transcripts. They are transcribed as long single-stranded RNA precursors with unique stem-loop structures that are processed by a DICER-Like (DCL) ribonuclease, typically DCL1, to produce mature miRNAs. Although a plethora of miRNAs have been found to be regulated by pathogen infection in plants, the biological function of most miRNAs remains largely unknown. Here, the contribution of OsDCL1 to rice immunity was investigated. Methods: Activation-tagged Osdcl1a (Osdcl1a-Ac) rice mutants were examined for resistance to pathogen infection. mRNA and small RNA deep sequencing, quantitative real-time PCR (RT-qPCR) and stem-loop reverse tanscripion-PCR (RT-PCR) were used to examine DCL1a-mediated alterations in the rice transcriptome. Ricediterpene phytoalexins were quantified by liquid chromatography-tandem mass spectrometry (LC-MSMS). Accumulation of O2·- was determined by nitroblue tetrazolium (NBT) staining. Key Results: dcl1a-Ac mutants exhibit enhanced susceptibility to infection by fungal pathogens which was associated with a weaker induction of defence gene expression. Comparison of the mRNA and miRNA transcriptomes of dcl1a-Ac and wild-type plants revealed misregulation of genes involved in detoxification of reactive oxygen species. Consequently, dcl1a-Ac plants accumulated O2·- in their leaves and were more sensitive to methyl viologen-induced oxidative stress. Furthermore, dcl1a-Ac plants showed downregulation of diterpenoidphytoalexin biosynthetic genes, these genes also being weakly induced during pathogen infection. Upon pathogen challenge, dcl1a-Ac plants failed to accumulate major diterpenoidphytoalexins. OsDCL1a activation resulted in marked alterations in the rice miRNAome, including both upregulation and downregulation of miRNAs. Conclusions: OsDCL1a activation enhances susceptibility to infection by fungal pathogens in rice. Activation of OsDCL1a represses the pathogen-inducible host defence response and negatively regulates diterpenoidphytoalexin production. These findings provide a basis to understand the molecular mechanisms through which OsDCL1a mediates rice immunity.
Authors: Rogerio Margis; Adriana F Fusaro; Neil A Smith; Shaun J Curtin; John M Watson; E Jean Finnegan; Peter M Waterhouse Journal: FEBS Lett Date: 2006-04-07 Impact factor: 4.124
Authors: Stephen A Goff; Darrell Ricke; Tien-Hung Lan; Gernot Presting; Ronglin Wang; Molly Dunn; Jane Glazebrook; Allen Sessions; Paul Oeller; Hemant Varma; David Hadley; Don Hutchison; Chris Martin; Fumiaki Katagiri; B Markus Lange; Todd Moughamer; Yu Xia; Paul Budworth; Jingping Zhong; Trini Miguel; Uta Paszkowski; Shiping Zhang; Michelle Colbert; Wei-lin Sun; Lili Chen; Bret Cooper; Sylvia Park; Todd Charles Wood; Long Mao; Peter Quail; Rod Wing; Ralph Dean; Yeisoo Yu; Andrey Zharkikh; Richard Shen; Sudhir Sahasrabudhe; Alun Thomas; Rob Cannings; Alexander Gutin; Dmitry Pruss; Julia Reid; Sean Tavtigian; Jeff Mitchell; Glenn Eldredge; Terri Scholl; Rose Mary Miller; Satish Bhatnagar; Nils Adey; Todd Rubano; Nadeem Tusneem; Rosann Robinson; Jane Feldhaus; Teresita Macalma; Arnold Oliphant; Steven Briggs Journal: Science Date: 2002-04-05 Impact factor: 47.728