Dissecting the genetic basis of wheat blast resistance in the Brazilian wheat cultivar BR 18-Terena

Goddard, Rachel; Steed, Andrew; Chinoy, Catherine; Ferreira, Jéssica Rosset; Scheeren, P. L.; Maciel, João Leodato Nunes; Caierão, E.; Torres, G. A. M.; Consoli, Luciano; Santana, F. M.; Fernandes, J. M. C.; Simmonds, James; Uauy, Cristóbal; Cockram, James; Nicholson, P.

doi:10.1186/s12870-020-02592-0

Cited by 36 publications

(28 citation statements)

References 51 publications

(68 reference statements)

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“…Despite the attempts on different GWAS algorithms, MTAs on the 2NS/2AS region were the only stably expressed QTL across experiments, and MTAs in other chromosome regions were hardly repeatable and have not been reported in other genetic studies (Ferreira et al, 2020;Goddard et al, 2020;He et al, 2020b;Juliana et al, 2020). This could be caused by 1) genomic regions with major effects on WB resistance were not present in this panel, 2) they were of very low frequencies below the detection power of the GWAS algorithms employed in this study, or 3) bias introduced by the 15K SNP chip that was developed based on genotypes without WB resistance genes that otherwise would be detected in this study.…”

Section: Discussionmentioning

confidence: 94%

Screening and Mapping for Head Blast Resistance in a Panel of CIMMYT and South Asian Bread Wheat Germplasm

Juliana

Kabir

et al. 2021

Front. Genet.

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Wheat blast (WB) is a destructive disease in South America and its first outbreak in Bangladesh in 2016 posed a great risk to food security of South Asian countries. A genome wide association study (GWAS) was conducted on a diverse panel of 184 wheat genotypes from South Asia and CIMMYT. Phenotyping was conducted in eight field experiments in Bolivia and Bangladesh and a greenhouse experiment in the United States. Genotypic data included 11,401 SNP markers of the Illumina Infinium 15K BeadChip and four additional STS markers on the 2NS/2AS translocation region. Accessions with stable WB resistance across experiments were identified, which were all 2NS carriers. Nevertheless, a dozen moderately resistant 2AS lines were identified, exhibiting big variation among experiments. Significant marker-trait associations (MTA) were detected on chromosomes 1BS, 2AS, 6BS, and 7BL; but only MTAs on 2AS at the 2NS/2AS translocation region were consistently significant across experiments. The resistant accessions identified in this study could be used in production in South Asian countries as a preemptive strategy to prevent WB outbreak.

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Section: Discussionmentioning

confidence: 94%

Screening and Mapping for Head Blast Resistance in a Panel of CIMMYT and South Asian Bread Wheat Germplasm

Juliana

Kabir

et al. 2021

Front. Genet.

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“…Additional minor quantitative trait loci (QTL) were identified on chromosomes 1AS, 2BL, 3AL, 4BS, 4DL, and 7BS, acting in an additive mode to 2NS translocation. In another study, Goddard et al (2020) mapped WB resistance in two mapping populations and identified five QTL for seedling blast resistance on chromosomes 2B, 4B, 5A, and 6A, and four QTL for head blast resistance on chromosomes 1A, 2B, 4A, and 5A, and concluded that the common resistant parent BR 18-Terena had quantitative resistance against WB. Additionally, genome-wide association studies (GWASs) for field WB resistance have been reported in international nurseries of CIMMYT (Juliana et al, 2019(Juliana et al, , 2020 and in a diverse panel of lines from South Asia and CIMMYT (He et al, 2021).…”

Section: Resistance Mechanism: Major Vs Minor Genesmentioning

confidence: 99%

Wheat Blast: A Disease Spreading by Intercontinental Jumps and Its Management Strategies

et al. 2021

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Wheat blast (WB) caused by Magnaporthe oryzae pathotype Triticum (MoT) is an important fungal disease in tropical and subtropical wheat production regions. The disease was initially identified in Brazil in 1985, and it subsequently spread to some major wheat-producing areas of the country as well as several South American countries such as Bolivia, Paraguay, and Argentina. In recent years, WB has been introduced to Bangladesh and Zambia via international wheat trade, threatening wheat production in South Asia and Southern Africa with the possible further spreading in these two continents. Resistance source is mostly limited to 2NS carriers, which are being eroded by newly emerged MoT isolates, demonstrating an urgent need for identification and utilization of non-2NS resistance sources. Fungicides are also being heavily relied on to manage WB that resulted in increasing fungal resistance, which should be addressed by utilization of new fungicides or rotating different fungicides. Additionally, quarantine measures, cultural practices, non-fungicidal chemical treatment, disease forecasting, biocontrol etc., are also effective components of integrated WB management, which could be used in combination with varietal resistance and fungicides to obtain reasonable management of this disease.

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“…Host genetic resistance is an important tool to integrate into disease management, but the progress in breeding for blast resistance has been challenged by a disease-conducive environment, especially in the tropics, as well as high variability in the fungal pathogen population (Coelho et al 2016;Rocha et al 2019;Gupta et al 2021;Duan et al 2021). Few wheat cultivars have been classified as resistant, or moderately resistant, to wheat blast, and in general most of them behave as moderately or fully susceptible to blast especially under disease-inductive weather conditions (Prestes et al 2007;Cruz et al 2012;Gomes et al 2019; Comissão Brasileira de Pesquisa de Trigo e Triticale 2020; Cruppe et al 2020;Goddard et al 2020;Dianese et al 2021;Roy et al 2021, Singh et al 2021.…”

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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Dissecting the genetic basis of wheat blast resistance in the Brazilian wheat cultivar BR 18-Terena

Cited by 36 publications

References 51 publications

Screening and Mapping for Head Blast Resistance in a Panel of CIMMYT and South Asian Bread Wheat Germplasm

Screening and Mapping for Head Blast Resistance in a Panel of CIMMYT and South Asian Bread Wheat Germplasm

Wheat Blast: A Disease Spreading by Intercontinental Jumps and Its Management Strategies

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

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