scholarly journals Identification of Magnaporthe oryzae Avirulence Genes to Three Rice Blast Resistance Genes

Plant Disease ◽  
2004 ◽  
Vol 88 (3) ◽  
pp. 265-270 ◽  
Author(s):  
C. X. Luo ◽  
Y. Fujita ◽  
N. Yasuda ◽  
K. Hirayae ◽  
T. Nakajima ◽  
...  
Keyword(s):  
Magnaporthe Oryzae ◽  
Goodness Of Fit ◽  
Blast Resistance ◽  
Random Amplified Polymorphic Dna ◽  
Rice Cultivars ◽  
Avirulence Genes ◽  
Rice Blast Resistance ◽  
Parental Isolate ◽  
Avr Gene ◽  
Avr Genes

The segregation of avirulence/virulence was studied in 115 F1 progeny isolates of Magnaporthe oryzae from a cross of two field isolates on three Japanese race-differential rice cultivars Kanto 51, Fukunishiki, and Toride 1. The χ2 tests of goodness-of-fit for a 1:1 ratio indicated that avirulence on cvs. Kanto 51, Fukunishiki, and Toride 1 was under monogenic control. The relationship between the avirulence (Avr) gene in the parental isolate and the Avr gene in the standard isolate was investigated by using 100 lines each of three F3 families from the crosses of the rice cultivars Norin 3/Kanto 51, AK61/Fukunishiki, and Norin 3/Toride 1, respectively. Based on the resistant reactions of the F3 rice lines to the parental isolates and the standard isolates harboring three known Avr genes, three genetically independent Avr genes, AvrPik, AvrPiz, and AvrPiz-t, were identified. The three identified Avr genes were mapped using random amplified polymorphic DNA (RAPD) analysis, and a partial linkage map was constructed with 17 RAPD markers closely linked to the Avr genes. Twelve markers and AvrPik, three markers and AvrPiz, and two markers and AvrPiz-t, as well as mating locus MAT1, constructed linkage groups A, B, and C, respectively.

scholarly journals A Rapid Survey of Avirulence Genes in Field Isolates of Magnaporthe oryzae

Plant Disease ◽  
2020 ◽  
Vol 104 (3) ◽  
pp. 717-723
Author(s):  
Zhen Zhang ◽  
Yulin Jia ◽  
Yanli Wang ◽  
Guochang Sun
Keyword(s):  
United States ◽  
Magnaporthe Oryzae ◽  
Blast Resistance ◽  
Blast Disease ◽  
Southern United States ◽  
R Genes ◽  
Field Isolates ◽  
Pcr Products ◽  
Avr Gene ◽  
Avr Genes

Magnaporthe oryzae is the causal agent for the devastating disease rice blast. The avirulence (AVR) genes in M. oryzae are required to initiate robust disease resistance mediated by the corresponding resistance (R) genes in rice. Therefore, monitoring pathogen AVR genes is important to predict the stability of R gene-mediated blast resistance. In the present study, we analyzed the DNA sequence dynamics of five AVR genes, namely, AVR-Pita1, AVR-Pik, AVR-Pizt, AVR-Pia, and AVR-Pii, in field isolates of M. oryzae in order to understand the effectiveness of the R genes, Pi-ta, Pi-k, Pi-zt, Pia, and Pii in the Southern U.S. rice growing region. Genomic DNA of 258 blast isolates collected from commercial fields of the Southern UNITED STATES during 1975–2009 were subjected to PCR amplification with AVR gene-specific PCR markers. PCR products were obtained from 232 isolates. The absence of PCR products in the remaining 26 isolates suggests that these isolates do not contain the tested AVR genes. Amplified PCR products were subsequently gel purified and sequenced. Based on the presence or absence of the five AVR genes, 232 field isolates were classified into 10 haplotype groups. The results revealed that 174 isolates of M. oryzae carried AVR-Pita1, 225 isolates carried AVR-Pizt, 44 isolates carried AVR-Pik, 3 isolates carried AVR-Pia, and one isolate carried AVR-Pii. AVR-Pita1 was highly variable, and 40 AVR-Pita1 haplotypes were identified in avirulent isolates. AVR-Pik had four nucleotide sequence site changes resulting in amino acid substitutions, whereas three other AVR genes, AVR-Pizt, AVR-Pia, and AVR-Pii, were relatively stable. Two AVR genes, AVR-Pik and AVR-Pizt, were found to exist in relatively larger proportions of the tested field isolates, which suggested that their corresponding R genes Pi-k and Pi-zt can be deployed in preventing blast disease in the Southern UNITED STATES in addition to Pi-ta. This study demonstrates that continued AVR gene monitoring in the pathogen population is critical for ensuring the effectiveness of deployed blast R genes in commercial rice fields.

Frequencies and Variations of Magnaporthe oryzae Avirulence Genes in Hunan Province, China

Plant Disease ◽  
2021 ◽  
Author(s):  
Zhirong Peng ◽  
Ling Li ◽  
Shenghai Wu ◽  
Xiaolin Chen ◽  
Yinfeng Shi ◽  
...  
Keyword(s):  
Magnaporthe Oryzae ◽  
Blast Resistance ◽  
Hunan Province ◽  
Start Codon ◽  
Nucleotide Polymorphisms ◽  
Avirulence Genes ◽  
Rice Varieties ◽  
Synonymous Mutations ◽  
Pathogen Populations ◽  
Avr Genes

Rice blast caused by Magnaporthe oryzae poses significant threaten to rice production. For breeding and deploying resistant rice varieties, it is essential to understand the frequencies and genetic variations of avirulence (AVR) genes in the pathogen populations. In this study, 444 isolates were collected from Hunan Province, China in 2012, 2015, and 2016, and their pathogenicity was evaluated by testing them on monogenic rice lines carrying resistance (R) genes Pita, Pizt, Pikm, Pib, or Pi9. The frequencies of corresponding AVR genes AVRPizt, AVRPikm, AVRPib, AVRPi9, and AVRPita were characterized by amplification and sequencing these genes in the isolates. Both Pi9 and Pikm conferred resistance to over 75% of the tested isolates, while Pizt, Pita, and Pib were effective against 55.63%, 15.31%, and 3.15% of the isolates, respectively. AVRPikm and AVRPi9 were detected in 90% of the isolates and AVRPita, AVRPizt, and AVRPib were present in 26.12%, 66.22%, and 79% of the isolates, respectively. Sequencing of AVR genes showed that most mutations were single nucleotide polymorphisms (SNPs), transposon insertions, and insertion mutations. The variable sites of AVRPikm and AVRPita were mainly located in the coding sequence (CDS) regions, and most were synonymous mutations. A 494 bp Pot2 transposon sequence insertion was found at the 87 bp upstream of the start codon in AVRPib. Noteworthy, although no mutations were found in CDS of AVRPi9, a GC-rich inserted sequence of ~200 bp was found at the 1272 bp upstream of the start codon in three virulent isolates. As AVRPikm and AVRPi9 were widely distributed with low genetic variation in the pathogen population, Pikm and Pi9 should be promising genes for breeding rice cultivars with blast resistance in Hunan.

scholarly journals Isolation and Characterization of Avirulence Genes in Magnaporthe oryzae

2017 ◽  
Vol 7 (1) ◽  
pp. 31-42 ◽  
Author(s):  
Mui Sie Jee ◽  
Leonard Whye Kit Lim ◽  
Martina Azelin Dirum ◽  
Sara Ilia Che Hashim ◽  
Muhammad Shafiq Masri ◽  
...  
Keyword(s):  
Magnaporthe Oryzae ◽  
Fungal Pathogen ◽  
Rice Blast ◽  
Avirulence Gene ◽  
Avirulence Genes ◽  
Isolation And Characterization ◽  
Molecular Pattern ◽  
Avr Gene ◽  
Avr Genes

Magnaporthe oryzae is a fungal pathogen contributing to rice blast diseases globally via their Avr (avirulence) gene. Although the occurrence of M. oryzae has been reported in Sarawak since several decades ago, however, none has focused specifically on Avr genes, which confer resistance against pathogen associated molecular pattern-triggered immunity (PTI) in host. The objective of this study is to isolate Avr genes from M. oryzae 7’ (a Sarawak isolate) that may contribute to susceptibility of rice towards diseases. In this study, AvrPiz-t, AVR-Pik, Avr-Pi54, and AVR-Pita1 genes were isolated via PCR and cloning approaches. The genes were then compared with set of similar genes from related isolates derived from NCBI. Results revealed that all eight Avr genes (including four other global isolates) shared similar N-myristoylation site and a novel motif. 3D modeling revealed similar β-sandwich structure in AvrPiz-t and AVR-Pik despite sequence dissimilarities. In conclusion, it is confirmed of the presence of these genes in the Sarawak (M. oryzae) isolate. This study implies that Sarawak isolate may confer similar avirulence properties as their counterparts worldwide. Further R/Avr gene-for-gene relationship studies may aid in strategic control of rice blast diseases in future.

scholarly journals AVR1-CO39 Is a Predominant Locus Governing the Broad Avirulence of Magnaporthe oryzae 2539 on Cultivated Rice (Oryza sativa L.)

2011 ◽  
Vol 24 (1) ◽  
pp. 13-17 ◽  
Author(s):  
Yan Zheng ◽  
Wenhui Zheng ◽  
Fucheng Lin ◽  
Ying Zhang ◽  
Yunping Yi ◽  
...  
Keyword(s):  
Oryza Sativa ◽  
Magnaporthe Oryzae ◽  
Oryza Sativa L ◽  
Experimental Results ◽  
R Gene ◽  
Rice Cultivars ◽  
Cultivated Rice ◽  
Avr Gene ◽  
Avr Genes

Magnaporthe oryzae 2539 was previously found to be avirulent to most rice cultivars and, therefore, was assumed to carry many avirulence (AVR) genes. However, only one AVR gene, AVR1-CO39, which corresponds to a resistance (R) gene Pi-CO39(t) in rice cv. CO39, has been found from 2539 thus far. In order to identify more AVR genes, we isolated 228 progeny strains from a cross between 2539 and Guy11, an M. oryzae strain with strong virulence on rice, and inoculated these strains onto 23 rice accessions (22 individual cultivars and a mixture of 14 cultivars) that are all resistant to 2539 but susceptible to Guy11. Unexpectedly, the experimental results indicated that the avirulence of 2539 on these rice cultivars appeared to be controlled only by the AVR1-CO39 locus. Consistent with this result, we further found that all except one of the rice cultivars were resistant to two transformed Guy11 strains carrying a 1.05-kb fragment containing the AVR1-CO39 gene from 2539. These results suggest that AVR1-CO39 is a predominant locus controlling the broad avirulence of 2539 on cultivated rice. Based on the results of this study and other previous studies, we infer that AVR1-CO39 is a species-wise rather than a cultivar-wise host-specific AVR locus of M. oryzae for rice.

Effector genes in Magnaporthe oryzae Triticum as Potential Targets for Incorporating Blast Resistance in Wheat

Plant Disease ◽  
2021 ◽  
Author(s):  
Monica Navia-Urrutia ◽  
Gloria Mosquera ◽  
Rebekah Ellsworth ◽  
Mark Farman ◽  
Harold N. Trick ◽  
...  
Keyword(s):  
Resistance Genes ◽  
Magnaporthe Oryzae ◽  
Rice Blast ◽  
Blast Resistance ◽  
Genetic Resistance ◽  
Avirulence Gene ◽  
Avirulence Genes ◽  
Rice Blast Resistance ◽  
Effector Genes ◽  
Transgenic Lines

Wheat blast (WB), caused by Magnaporthe oryzae Triticum pathotype, recently emerged as a destructive disease that threatens global wheat production. Since few sources of genetic resistance have been identified in wheat, genetic transformation of wheat with rice blast resistance genes could expand resistance to WB. We evaluated the presence/absence of homologs of rice blast effector genes in Triticum isolates with the aim of identifying avirulence genes in field populations whose cognate rice resistance genes could potentially confer resistance to WB. We also assessed presence of the wheat pathogen AVR-Rmg8 gene, and identified new alleles. A total of 102 isolates collected in Brazil, Bolivia and Paraguay from 1986 to 2018 were evaluated by PCR using 21 pairs of gene-specific primers. Effector gene composition was highly variable, with homologs to AvrPiz-t, AVR-Pi9, AVR-Pi54 and ACE1 showing the highest amplification frequencies (>94%). We identified Triticum isolates with a functional AvrPiz-t homolog that triggers Piz-t-mediated resistance in the rice pathosystem, and produced transgenic wheat plants expressing the rice Piz-t gene. Seedlings and heads of the transgenic lines were challenged with isolate T25 carrying functional AvrPiz-t. Although slight decreases in the percentage of diseased spikelets and leaf area infected were observed in two transgenic lines, our results indicated that Piz-t did not confer useful WB resistance. Monitoring of avirulence genes in populations is fundamental to identifying effective resistance genes for incorporation into wheat by conventional breeding or transgenesis. Based on avirulence gene distributions, rice resistance genes Pi9 and Pi54 might be candidates for future studies.

scholarly journals Osa-miR162a balances rice yield and resistance to Magnaporthe oryzae

2020 ◽  
Author(s):  
Xu-Pu Li ◽  
Xiao-Chun Ma ◽  
He Wang ◽  
Yong Zhu ◽  
Xin-Xian Liu ◽  
...  
Keyword(s):  
Magnaporthe Oryzae ◽  
Rice Blast ◽  
Rice Yield ◽  
Blast Resistance ◽  
Blast Disease ◽  
Mirna Biogenesis ◽  
Trade Off ◽  
Rice Blast Resistance ◽  
Defense Related Gene ◽  
Transgenic Lines

Abstract MicroRNAs (miRNAs) play essential roles in rice immunity against Magnaporthe oryzae, the causative agent of rice blast disease. Osa-miR162a targets Dicer-like 1 (DCL1) genes, which play vital roles in miRNA biogenesis and act as negative regulators in rice immunity. Here we demonstrate that Osa-miR162a improves rice immunity against M. oryzae and balances the trade-off between rice yield and resistance. Overexpression of Osa-miR162a compromises rice susceptibility to M. oryzae accompanying enhanced induction of defense-related genes and accumulation of hydrogen peroxide (H2O2). In contrast, blocking miR162 by overexpressing a target mimic of miR162 enhances susceptibility to blast fungus associating with compromised induction of defense-related gene expression and H2O2 accumulation. Moreover, the transgenic lines overexpressing Osa-miR162a display decreased seed setting rate resulting in reduced yield per plant, whereas blocking miR162 leads to an increased number of grains per panicle, resulting in increased yield per plant. Altered accumulation of miR162 had limited impact on the expression of OsDCL1. Together, our results indicate that Osa-miR162a improves rice blast resistance and plays a role in the balance of trade-off between resistance and yield.

scholarly journals Genotyping-by-Sequencing-Based Genetic Analysis of African Rice Cultivars and Association Mapping of Blast Resistance Genes Against Magnaporthe oryzae Populations in Africa

2017 ◽  
Vol 107 (9) ◽  
pp. 1039-1046 ◽  
Author(s):  
Emmanuel M. Mgonja ◽  
Chan Ho Park ◽  
Houxiang Kang ◽  
Elias G. Balimponya ◽  
Stephen Opiyo ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Association Mapping ◽  
Magnaporthe Oryzae ◽  
Rice Blast ◽  
Blast Resistance ◽  
Genotyping By Sequencing ◽  
Rice Breeding ◽  
Rice Cultivars ◽  
R Genes ◽  
African Rice

Understanding the genetic diversity of rice germplasm is important for the sustainable use of genetic materials in rice breeding and production. Africa is rich in rice genetic resources that can be utilized to boost rice productivity on the continent. A major constraint to rice production in Africa is rice blast, caused by the hemibiotrophic fungal pathogen Magnaporthe oryzae. In this report, we present the results of a genotyping-by-sequencing (GBS)-based diversity analysis of 190 African rice cultivars and an association mapping of blast resistance (R) genes and quantitative trait loci (QTLs). The 190 African cultivars were clustered into three groups based on the 184K single nucleotide polymorphisms generated by GBS. We inoculated the rice cultivars with six African M. oryzae isolates. Association mapping identified 25 genomic regions associated with blast resistance (RABRs) in the rice genome. Moreover, PCR analysis indicated that RABR_23 is associated with the Pi-ta gene on chromosome 12. Our study demonstrates that the combination of GBS-based genetic diversity population analysis and association mapping is effective in identifying rice blast R genes/QTLs that contribute to resistance against African populations of M. oryzae. The identified markers linked to the RABRs and 14 highly resistant cultivars in this study will be useful for rice breeding in Africa.

scholarly journals Integrated Analysis of Gene Expression, SNP, InDel, and CNV Identifies Candidate Avirulence Genes in Australian Isolates of the Wheat Leaf Rust Pathogen Puccinia triticina

Genes ◽  
2020 ◽  
Vol 11 (9) ◽  
pp. 1107
Author(s):  
Long Song ◽  
Jing Qin Wu ◽  
Chong Mei Dong ◽  
Robert F. Park
Keyword(s):  
Gene Expression ◽  
Leaf Rust ◽  
De Novo ◽  
Puccinia Triticina ◽  
Integrated Analysis ◽  
Avirulence Genes ◽  
Integrated Framework ◽  
Rust Pathogen ◽  
Avr Gene ◽  
Avr Genes

The leaf rust pathogen, Puccinia triticina (Pt), threatens global wheat production. The deployment of leaf rust (Lr) resistance (R) genes in wheat varieties is often followed by the development of matching virulence in Pt due to presumed changes in avirulence (Avr) genes in Pt. Identifying such Avr genes is a crucial step to understand the mechanisms of wheat-rust interactions. This study is the first to develop and apply an integrated framework of gene expression, single nucleotide polymorphism (SNP), insertion/deletion (InDel), and copy number variation (CNV) analysis in a rust fungus and identify candidate avirulence genes. Using a long-read based de novo genome assembly of an isolate of Pt (‘Pt104’) as the reference, whole-genome resequencing data of 12 Pt pathotypes derived from three lineages Pt104, Pt53, and Pt76 were analyzed. Candidate avirulence genes were identified by correlating virulence profiles with small variants (SNP and InDel) and CNV, and RNA-seq data of an additional three Pt isolates to validate expression of genes encoding secreted proteins (SPs). Out of the annotated 29,043 genes, 2392 genes were selected as SP genes with detectable expression levels. Small variant comparisons between the isolates identified 27–40 candidates and CNV analysis identified 14–31 candidates for each Avr gene, which when combined, yielded the final 40, 64, and 69 candidates for AvrLr1, AvrLr15, and AvrLr24, respectively. Taken together, our results will facilitate future work on experimental validation and cloning of Avr genes. In addition, the integrated framework of data analysis that we have developed and reported provides a more comprehensive approach for Avr gene mining than is currently available.

scholarly journals Geographic Distribution of Avirulence Genes of the Rice Blast Fungus Magnaporthe oryzae in the Philippines

2019 ◽  
Vol 7 (1) ◽  
pp. 23 ◽  
Author(s):  
Ana Lopez ◽  
Tapani Yli-Matilla ◽  
Christian Cumagun
Keyword(s):  
Geographic Distribution ◽  
Magnaporthe Oryzae ◽  
Rice Blast ◽  
Rice Blast Fungus ◽  
The Philippines ◽  
R Genes ◽  
Avirulence Genes ◽  
Geographic Locations ◽  
Avr Genes ◽  
Pcr Test

A total of 131 contemporary and 33 reference isolates representing a number of multi-locus genotypes of Magnaporthe oryzae were subjected to a PCR test to detect the presence/absence of avirulence (Avr) genes. Results revealed that the more frequently occurring genes were Avr-Pik (81.50%), Avr-Pita (64.16%) and Avr-Pii (47.98%), whereas the less frequently occurring genes were Avr-Pizt (19.08%) and Avr-Pia (5.20%). It was also laid out that the presence of Avr genes in M. oryzae is strongly associated with agroecosystems where the complementary resistant (R) genes exist. No significant association, however, was noted on the functional Avr genes and the major geographic locations. Furthermore, it was identified that the upland varieties locally known as “Milagrosa” and “Waray” contained all the R genes complementary to the Avr genes tested.

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