Effectiveness of the Wheat Blast Resistance Gene Rmg8 in Bangladesh Suggested by Distribution of an AVR-Rmg8 Allele in the Pyricularia oryzae Population

Horo, Jemal Tola; Asuke, Soichiro; Vy, Trinh Thi Phuong; Tosa, Yukio

doi:10.1094/phyto-03-20-0073-r

Cited by 9 publications

(15 citation statements)

References 22 publications

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“…S11). B71 lineage isolates also lack the PWT4 effector, which is known to suppress AVR-Rmg8-elicited resistance (Horo et al 2020;Inoue et al 2021). These genome analyses predict that the B71 lineage isolates (AVR-Rmg8 positive, PWT4 negative) cannot infect wheat plants with the matching disease resistance gene Rmg8.…”

Section: Main Textmentioning

confidence: 94%

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A pandemic clonal lineage of the wheat blast fungus

Latorre

Were

Foster

et al. 2022

Preprint

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Wheat, the most important food crop, is threatened by a blast disease pandemic. Here, we show that a clonal lineage of the wheat blast fungus recently spread to Asia and Africa following two independent introductions from South America. Through a combination of genome analyses and laboratory experiments, we show that the decade-old blast pandemic lineage can be controlled by the Rmg8 disease resistance gene and is sensitive to strobilurin fungicides. However, we also highlight the potential of the pandemic clone to evolve fungicide-insensitive variants and sexually recombine with African lineages. This underscores the urgent need for genomic surveillance to track and mitigate the spread of wheat blast outside of South America, and to guide pre-emptive wheat breeding for blast resistance.

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Section: Main Textmentioning

confidence: 94%

“…S11). B71 lineage isolates also lack the PWT4 effector, which is known to suppress AVR-Rmg8-elicited resistance (Horo et al 2020; Inoue et al 2021).…”

Section: Main Textmentioning

confidence: 99%

A pandemic clonal lineage of the wheat blast fungus

Latorre

Were

Foster

et al. 2022

Preprint

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“…So far, genetic studies on WB resistance have been mostly limited to elite germplasm, hence there is a need to investigate landraces, synthetic wheat and wild relatives for novel sources/genes for WB resistance. A good example is the landrace GR119 [23] which is a novel resistance source against WB and carries two genes Rmg 8 and Rmg GR119 for WB resistance. Identifying novel MTAs using non-2NS genotypes is suggested for future GWAS studies to avoid their effects being masked by 2NS translocation.…”

Section: Discussionmentioning

confidence: 99%

“…Other genes like Rmg1, Rmg 4, Rmg 5 and Rmg 6 are resistant against non-MoT strains of M. oryzae [19][20][21]. The gene Rmg 8 in combination with Rmg GR119 confers good resistance to MoT isolates from Brazil and Bangladesh at the heading stage primarily in controlled environments, implying their promising utilization in breeding programs [16,[22][23][24]. Apart from the Rmg genes, QTL mapping and genome-wide association studies (GWAS) have also identified numerous QTLs and marker trait associations (MTAs) on various wheat chromosomes.…”

Section: Introductionmentioning

confidence: 99%

Identification of Genomic Regions and Sources for Wheat Blast Resistance through GWAS in Indian Wheat Genotypes

Phuke

Juliana

et al. 2022

Genes

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Wheat blast (WB) is a devastating fungal disease that has recently spread to Bangladesh and poses a threat to the wheat production in India, which is the second-largest wheat producing country in the world. In this study, 350 Indian wheat genotypes were evaluated for WB resistance in 12 field experiments in three different locations, namely Jashore in Bangladesh and Quirusillas and Okinawa in Bolivia. Single nucleotide polymorphisms (SNPs) across the genome were obtained using DArTseq® technology, and 7554 filtered SNP markers were selected for a genome-wide association study (GWAS). All the three GWAS approaches used identified the 2NS translocation as the only major source of resistance, explaining up to 32% of the phenotypic variation. Additional marker-trait associations were located on chromosomes 2B, 3B, 4D, 5A and 7A, and the combined effect of three SNPs (2B_180938790, 7A_752501634 and 5A_618682953) showed better resistance, indicating their additive effects on WB resistance. Among the 298 bread wheat genotypes, 89 (29.9%) carried the 2NS translocation, the majority of which (60 genotypes) were CIMMYT introductions, and 29 were from India. The 2NS carriers with a grand mean WB index of 6.6 showed higher blast resistance compared to the non-2NS genotypes with a mean index of 46.5. Of the 52 durum wheats, only one genotype, HI 8819, had the 2NS translocation and was the most resistant, with a grand mean WB index of 0.93. Our study suggests that the 2NS translocation is the only major resistance source in the Indian wheat panel analysed and emphasizes the urgent need to identify novel non-2NS resistance sources and genomic regions.

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“…Air temperatures greater than 26°C and the genetic variability of the blast population observed in more aggressive Triticum lineage races had been the most important factors negatively affecting the genes' effectiveness. Therefore, durable and effective resistance is yet to be sourced and incorporated into commercial materials (Takabayashi et al 2002;Hau et al 2007;Zhan et al 2008;Nga et al 2009;Tagle et al 2015;Anh et al 2015Anh et al , 2018Cruz et al 2016b;Wang et al 2018;Asuke et al 2019Asuke et al , 2021Horo et al 2020;Jiang et al 2020;Inoue et al 2021;Dianese et al 2021). The efficiency of the photosynthetic apparatus affected the blast resistance response on one wheat commercial line moderately resistant and another one susceptible.…”

Section: Wheat Blast Managementmentioning

confidence: 99%

Taxonomic and pathogenic diversity of the blast pathogen populations infecting wheat and grasses in Minas Gerais

Ascari¹,

Ponte²

2021

Preprint

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The blast disease of Poaceae is caused by a large species complex, among which P. oryzae is composed of several host-specialized lineages. The Pyricularia oryzae Triticum pathotype (PoT) causes the blast disease in wheat, but is also capable of infecting other grasses, which may serve as an inoculum reservoir for epidemics in wheat. In Brazil, severe wheat blast epidemics are most common in the Cerrado region. The dominant hypothesis is that signal grass (Urochloa sp.) and other gramineous plants harbor the wheat blast pathogen, thus serving as a major reservoir of inoculum for epidemics in wheat. A two-year survey of the Pyricularia blast pathogens was conducted in both wheat and non-wheat areas as well as prior (February) and during (May) the wheat growing season in Minas Gerais. A total of 1,368 plant samples representative of 31 Poaceae species, including wheat, were collected and inspected for the presence of blast symptoms. During the isolations, 932 isolates were obtained, being one fourth obtained from gramineous plants. A subset of 572 isolates was selected for identification at the species level based on portions of the CH7-BAC9 gene sequences. Most of the isolates (n = 494) were P. oryzae, within which 68% were PoT and 32% non-PoT based on two PCR assays targeting (MoT3 and C17 PCR assays). The PoT lineage was found predominantly (97%) in wheat and rarely in the other hosts, even nearby wheat fields (2.1%), as well as at longer distances from wheat regions (0.1%). The blast pathogen population isolated from signal grass grouped in different clades from PoT, and therefore referred to Urochloa lineage (PoU). A series of cross-inoculation greenhouse experiments was conducted using wheat (cv. BRS Guamirim and BR 18-Terena) and signal grass (cv. Marandu) as host and 14 PoT and six PoU isolates as pathogen factor. In the first leaf-inoculation experiment, results showed a significant interaction between host and pathogen; PoT was strongly/weakly aggressive towards wheat/signal grass and PoU was strongly/weakly aggressive towards signal grass/wheat. In inoculated wheat heads, PoT was more aggressive (>91% infected spikelets) than PoU (52% infected spikelets). In a third experiment, four signal grass cultivars (Marandu, Basilisk, Piatã, and Xaraés) were inoculated with the same set of 20 isolates. Similarly, signal grass cultivars were generally more susceptible to PoU than PoT. Severity induced by PoU was twice (7.7% severity) as high as PoT (3.8%) and so was the number of conidia/leaf produced by PoU (47,500) and PoT (23,200). Two groups of signal grass cultivars were formed, the most susceptible composed of Marandu and Basilisk and the least susceptible composed of Piatã and Xaraés. Results of our study confirm the host-specialization and the shaping of the blast populations according to the host. We further suggest that grasses in general, especially signal grass, may not play a major role as an inoculum reservoir for PoT, as it harbors mainly the PoU population. However, due to the large extent of pasture-growing regions and cross-infection ability in wheat, signal grass may harbor amounts of PoT inoculum that are sufficient for initiating leaf and head blast epidemics in wheat blast in Minas Gerais state.

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Effectiveness of the Wheat Blast Resistance Gene Rmg8 in Bangladesh Suggested by Distribution of an AVR-Rmg8 Allele in the Pyricularia oryzae Population

Cited by 9 publications

References 22 publications

A pandemic clonal lineage of the wheat blast fungus

A pandemic clonal lineage of the wheat blast fungus

Identification of Genomic Regions and Sources for Wheat Blast Resistance through GWAS in Indian Wheat Genotypes

Taxonomic and pathogenic diversity of the blast pathogen populations infecting wheat and grasses in Minas Gerais

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