scholarly journals Osa-miR7695 enhances transcriptional priming in defense responses against the rice blast fungus

2019 ◽  
Vol 19 (1) ◽  
Author(s):  
Ferran Sánchez-Sanuy ◽  
Cristina Peris-Peris ◽  
Shiho Tomiyama ◽  
Kazunori Okada ◽  
Yue-Ie Hsing ◽  
...  
Keyword(s):  
Rice Blast ◽  
Blast Resistance ◽  
Rice Blast Fungus ◽  
Wild Type ◽  
Biosynthetic Genes ◽  
Pathogen Infection ◽  
High Iron ◽  
Rice Plants ◽  
Iron Supply ◽  
Blast Fungus

Abstract Background MicroRNAs (miRNAs) are small non-coding RNAs that regulate gene expression at the post-transcriptional level in eukaryotes. In rice, MIR7695 expression is regulated by infection with the rice blast fungus Magnaporthe oryzae with subsequent down-regulation of an alternatively spliced transcript of natural resistance-associated macrophage protein 6 (OsNramp6). NRAMP6 functions as an iron transporter in rice. Results Rice plants grown under high iron supply showed blast resistance, which supports that iron is a factor in controlling blast resistance. During pathogen infection, iron accumulated in the vicinity of M. oryzae appressoria, the sites of pathogen entry, and in cells surrounding infected regions of the rice leaf. Activation-tagged MIR7695 rice plants (MIR7695-Ac) exhibited enhanced iron accumulation and resistance to M. oryzae infection. RNA-seq analysis revealed that blast resistance in MIR7695-Ac plants was associated with strong induction of defense-related genes, including pathogenesis-related and diterpenoid biosynthetic genes. Levels of phytoalexins during pathogen infection were higher in MIR7695-Ac than wild-type plants. Early phytoalexin biosynthetic genes, OsCPS2 and OsCPS4, were also highly upregulated in wild-type rice plants grown under high iron supply. Conclusions Our data support a positive role of miR7695 in regulating rice immunity that further underpin links between defense and iron signaling in rice. These findings provides a basis to better understand regulatory mechanisms involved in rice immunity in which miR7695 participates which has a great potential for the development of strategies to improve blast resistance in rice.

scholarly journals The Role of Silicon in Preventing Appressorial Penetration by the Rice Blast Fungus

2008 ◽  
Vol 98 (9) ◽  
pp. 1038-1044 ◽  
Author(s):  
T. Hayasaka ◽  
H. Fujii ◽  
K. Ishiguro
Keyword(s):  
Silica Gel ◽  
Rice Blast ◽  
Rice Blast Fungus ◽  
Leaf Epidermis ◽  
Adaxial Surface ◽  
Rice Plants ◽  
Blast Fungus ◽  
Spray Inoculation ◽  
Rice Leaves

To test the hypothesis that silicon (Si) confers resistance against appressorial penetration of the rice blast fungus, the proportion of appressorial penetration into the leaf epidermis to total appressoria formed was compared among rice plants amended with various rates of silica gel to those plants nonamended. The amounts of Si in the youngest leaves were consistent with the amounts of silica gel applied to the rice plants. Relative Si levels on the adaxial surface of leaves as detected by energy dispersive X-ray analysis also increased with the amounts of silica gel applied. Based on light microscopic observation of the adaxial surface of rice leaves, the proportion of appressorial penetration was reduced by increasing amounts of silica gel applied and increased with the length of period after spray inoculation. Consequently, these results strongly support the hypothesis and suggest that Si in the leaf epidermis may confer resistance against appressorial penetration. Meanwhile, the number of lesions per leaf also decreased with the amount of Si applied, while only a certain part of penetrated appressoria could become sporulating susceptible lesions. This suggests that Si also confers physiological resistance against blast infection after the penetration.

scholarly journals OsNAC111, a Blast Disease–Responsive Transcription Factor in Rice, Positively Regulates the Expression of Defense-Related Genes

2014 ◽  
Vol 27 (10) ◽  
pp. 1027-1034 ◽  
Author(s):  
Naoki Yokotani ◽  
Tomoko Tsuchida-Mayama ◽  
Hiroaki Ichikawa ◽  
Nobutaka Mitsuda ◽  
Masaru Ohme-Takagi ◽  
...  
Keyword(s):  
Transcription Factor ◽  
Transgenic Rice ◽  
Transcriptional Activation ◽  
Rice Blast ◽  
Rice Blast Fungus ◽  
Blast Disease ◽  
Pr Genes ◽  
Rice Plants ◽  
Blast Fungus ◽  
Transgenic Rice Plants

Plants respond to pathogen attack by transcriptionally regulating defense-related genes via various types of transcription factors. We identified a transcription factor in rice, OsNAC111, belonging to the TERN subgroup of the NAC family that was transcriptionally upregulated after rice blast fungus (Magnaporthe oryzae) inoculation. OsNAC111 was localized in the nucleus of rice cells and had transcriptional activation activity in yeast and rice cells. Transgenic rice plants overexpressing OsNAC111 showed increased resistance to the rice blast fungus. In OsNAC111-overexpressing plants, the expression of several defense-related genes, including pathogenesis-related (PR) genes, was constitutively high compared with the control. These genes all showed blast disease-responsive expression in leaves. Among them, two chitinase genes and one β-1,3-glucanase gene showed reduced expression in transgenic rice plants in which OsNAC111 function was suppressed by a chimeric repressor (OsNAC111-SRDX). OsNAC111 activated transcription from the promoters of the chitinase and β-1,3-glucanase genes in rice cells. In addition, brown pigmentation at the infection sites, a defense response of rice cells to the blast fungus, was lowered in OsNAC111-SRDX plants at the early infection stage. These results indicate that OsNAC111 positively regulates the expression of a specific set of PR genes in the disease response and contributes to disease resistance.

scholarly journals Identification and Characterization of 2′-Deoxyuridine from the Supernatant of Conidial Suspensions of Rice Blast Fungus as an Infection-Promoting Factor in Rice Plants

2011 ◽  
Vol 24 (5) ◽  
pp. 519-532 ◽  
Author(s):  
Sugihiro Ando ◽  
Yuko Sato ◽  
Hideyuki Shigemori ◽  
Takafumi Shimizu ◽  
Kazunori Okada ◽  
...  
Keyword(s):  
Rice Blast ◽  
Chemical Structure ◽  
Rice Blast Fungus ◽  
Conidial Suspension ◽  
Rice Plants ◽  
Blast Fungus ◽  
Plant Pathogen Interactions ◽  
Identification And Characterization ◽  
Compatible Interactions

We previously detected infection-promoting activity in the supernatant of the conidial suspension (SCS) of the rice blast fungus. In the present study, a molecule carrying the activity was purified and identified as 2′-deoxyuridine (dU). The infection-promoting activity of dU was strictly dependent on its chemical structure and displayed characteristics consistent with those of the SCS. Notably, the activity of dU was exclusively detected during interactions between rice and virulent isolates of the fungus, the number of susceptible lesions in leaf blades was increased by dU, and nonhost resistance in rice plants was not affected by treatment with dU. In addition, the expression of pathogensis-related genes, accumulation of H2O2, and production of phytoalexins in rice in response to inoculation with virulent fungal isolates was not suppressed by dU. The infection-promoting activity of dU was not accompanied by elevated levels of endogenous abscissic acid, which is known to modify plant-pathogen interactions, and was not detected in interactions between oat plants and a virulent oat blast fungus isolate. Taken together, these results demonstrate that dU is a novel infection-promoting factor that acts specifically during compatible interactions between rice plants and rice blast fungus in a mode distinct from that of toxins and suppressors.

Induction of Resistance against Rice Blast Fungus in Rice Plants Treated with a Potent Elicitor,N-Acetylchitooligosaccharide

2006 ◽  
Vol 70 (7) ◽  
pp. 1599-1605 ◽  
Author(s):  
Shigeru TANABE ◽  
Mitsuo OKADA ◽  
Yusuke JIKUMARU ◽  
Hisakazu YAMANE ◽  
Hanae KAKU ◽  
...  
Keyword(s):  
Rice Blast ◽  
Rice Blast Fungus ◽  
Rice Plants ◽  
Blast Fungus ◽  
Induction Of Resistance

scholarly journals Transposon impala, a Novel Tool for Gene Tagging in the Rice Blast Fungus Magnaporthe grisea

2001 ◽  
Vol 14 (3) ◽  
pp. 308-315 ◽  
Author(s):  
François Villalba ◽  
Marc-Henri Lebrun ◽  
Aurélie Hua-Van ◽  
Marie-Josée Daboussi ◽  
Marie-Claire Grosjean-Cournoyer
Keyword(s):  
Nitrate Reductase ◽  
Fusarium Oxysporum ◽  
Rice Blast ◽  
Insertional Mutagenesis ◽  
Magnaporthe Grisea ◽  
Rice Blast Fungus ◽  
Single Copy ◽  
Wild Type ◽  
Type Locus ◽  
Blast Fungus

impala, a Tc1-mariner transposable element from Fusarium oxysporum, was introduced into the rice blast fungus Magnaporthe grisea to develop transposon-based insertional mutagenesis. A construct (pNIL160) containing an autonomous impala copy inserted in the promoter of niaD encoding Aspergillus nidulans nitrate reductase was introduced by transformation into a M. grisea nitrate reductase-deficient mutant. impala excision was monitored by restoration of prototrophy for nitrate. Southern analysis of niaD+ revertants revealed that impala was able to excise and reinsert at new loci in M. grisea. As observed for its host Fusarium oxysporum, impala inserted at a TA site left a typical excision footprint of 5 bp. We have shown that a defective impala copy was inactive in M. grisea, yet it can be activated by a functional impala transposase. A transformant carrying a single copy of pNIL160 was used to generate a collection of 350 revertants. Mutants either altered for their mycelial growth (Rev2) or nonpathogenic (Rev77) were obtained. Complementation of Rev77 with a 3-kb genomic fragment from a wild-type locus was successful, demonstrating the tagging of a pathogenicity gene by impala. This gene, called ORP1, is essential for penetration of host leaves by M. grisea and has no sequence homology to known genes.

Oxygenated Fatty Acids with Anti-rice Blast Fungus Activity in Rice Plants

1993 ◽  
Vol 57 (2) ◽  
pp. 283-287 ◽  
Author(s):  
Tadahiro Kato ◽  
Yoshihiro Yamaguchi ◽  
Tsuneo Namai ◽  
Toshifumi Hirukawa
Keyword(s):  
Fatty Acids ◽  
Rice Blast ◽  
Rice Blast Fungus ◽  
Rice Plants ◽  
Blast Fungus ◽  
Oxygenated Fatty Acids

Expression of a bacterial chitosanase in rice plants improves disease resistance to the rice blast fungus Magnaporthe oryzae

2011 ◽  
Vol 31 (4) ◽  
pp. 629-636 ◽  
Author(s):  
Yusuke Kouzai ◽  
Susumu Mochizuki ◽  
Akihiro Saito ◽  
Akikazu Ando ◽  
Eiichi Minami ◽  
...  
Keyword(s):  
Disease Resistance ◽  
Magnaporthe Oryzae ◽  
Rice Blast ◽  
Rice Blast Fungus ◽  
Rice Plants ◽  
Blast Fungus

scholarly journals Identification of miRNAs Contributing to the Broad-Spectrum and Durable Blast Resistance in the Yunnan Local Rice Germplasm

2021 ◽  
Vol 12 ◽  
Author(s):  
Jinlu Li ◽  
Hui Zhang ◽  
Rui Yang ◽  
Qianchun Zeng ◽  
Guangyu Han ◽  
...  
Keyword(s):  
Broad Spectrum ◽  
Rice Blast ◽  
Target Genes ◽  
Blast Resistance ◽  
Rice Blast Fungus ◽  
Defense Responses ◽  
Resistant Variety ◽  
Post Inoculation ◽  
Significant Information ◽  
Blast Fungus

MicroRNAs are 20–24 nucleotide non-coding RNAs and play important roles in plant-environment interactions. In recent years, many microRNAs (miRNAs) have been found to regulate rice immunity against rice blast fungus. However, there are limited studies about miRNAs that directly target resistance (R) genes to regulate rice immunity. In this study, by deep sequencing, small RNA libraries were constructed from four-leaf stage seedlings of the resistant variety Ziyu44 and susceptible variety Jiangnanxiangnuo (JNXN) upon Magnaporthe oryzae infection, we found that much more miRNAs were significantly differentially expressed in Ziyu44 than in JNXN. Among these miRNAs, we focused on miR9664, a newly identified rice miRNA in our sequencing, which was upregulated lightly in Ziyu44 and drastically in JNXN at 24–48 h post-inoculation (hpi). The transgenic plants overexpressing miR9664 (miR9664-oe) displayed reduced defense responses to M. oryzae, while those knocking down miR9664 (miR9664-m) displayed enhanced defense responses to M. oryzae. Most of the detected miR9664 predicted target genes were reduced in the miR9664-oe lines while increased in the miR9664-m lines. The cleavage site of LOC_Os08g07774 was confirmed by RLM-RACE. Meanwhile, after being inoculated with M. oryzae, the genes were expressed differently between Ziyu44 and JNXN. The results suggest that miR9664-mediated R gene turnover contributes to Ziyu44 broad-spectrum resistance to rice blast fungus. Taken together, our research identified a new rice miRNA that directly targets R genes to regulate rice immunity against rice blast fungus, adding significant information to the study of rice–M. oryzae interaction.

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