the only resistance

gene is failing

Notes made while writing and checking this brief, shown as written. They use working shorthand.

EMBRAPA is Brazil's federal agricultural research enterprise and the primary institutional source for wheat blast data, pathogen characterization, and resistance breeding. The Phytopathology Research article synthesizes international outbreak data and genomic surveillance. Source type: Self-articulated (EMBRAPA institutional research reporting on problems defined and characterized by Brazilian and Bangladeshi national research programs; CIMMYT/CGIAR also involved as co-investigators rather than external commentators).

Reconciliation 2026-09-29: Both cited sources were read in full on 2026-09-29. The EMBRAPA page at the cited address now shows only its headline and date, with a notice that some older news is hidden during an electoral period, so the article was read from the Internet Archive copy of the same page saved on 2024-09-12 (web.archive.org/web/20240912103650/https://www.embrapa.br/en/busca-de-noticias/-/noticia/92225154/com-mudancas-climaticas-brusone-pode-reduzir-em-13-a-producao-mundial-do-trigo). The publisher's page for the Phytopathology Research review blocks automated reading, so the review and its four tables were read from Internet Archive copies of the publisher's pages saved in 2025, and the citation was checked against the Crossref record for DOI 10.1186/s42483-020-00067-6. Changes: (1) The text said the disease had spread "across southern Africa." The EMBRAPA article reports Zambia in 2018 and no other African country, and the review does not mention Africa as affected. The phrase was removed. (2) The text said fungicides work poorly because the fungus infects during a brief flowering window when the plant limits how far fungicide can travel. Neither source gives that reason. The review says fungicide efficacy is low, that sprays work very poorly once symptoms show on the head, and that the fungus is developing fungicide resistance. The sentence now says that. (3) The text said the 13.5 million hectares at risk by 2050 would be concentrated in subtropical wheat belts with thin food security margins. The EMBRAPA article says the disease could reach every continent except Antarctica, including the United States, Italy, Spain, France, Japan, New Zealand and Australia, and that 6.4 million hectares are under threat today. The sentence now gives those facts. (4) The text said wheat is the main source of calories for more than 2.5 billion people and that the affected zones are among the most food-insecure in the world. Neither source says this. The review says wheat is the third largest cereal crop after corn and rice and the leading source of plant protein in human food, and the sentence now says that. (5) The text said "EMBRAPA modeling" projects a 13% loss "under high-emission scenarios" that would push hundreds of millions of people below minimum calorie intake. The EMBRAPA article reports a study published in Nature Climate Change and organized by CIMMYT, does not name an emissions scenario, and gives no count of people. It gives a 13% reduction by around 2050 and losses that could reach 69 million tons of wheat per year. The sentence now says that. (6) The text said 2NS gave decades of field resistance and is overcome by a virulence group called Triticum 4 (T4) circulating in Brazil and Bangladesh. Neither source mentions T4 or gives a length of time. The review says 2NS varieties resist most isolates, that a few highly virulent isolates such as B71 have eroded that resistance, and that 2NS varieties are grown in Brazil, Bolivia, Paraguay and Bangladesh. The sentence now says that. (7) The text described the Brazilian cultivar BR 18-Terena as a breeding parent whose resistance went uncharacterized for decades, and later said that characterizing it would allow transfer into elite lines in Bangladesh, Zambia and Bolivia within 5 to 7 breeding cycles. Neither source mentions BR 18-Terena or a number of breeding cycles. Both sentences were replaced with what the review says about the other resistance genes: Rmg1 to Rmg7 mostly fail at higher temperatures or in the field, Rmg8 and RmgGR119 still need field confirmation and are being stacked with 2NS, and marker-assisted selection and speed breeding can speed up breeding. (8) The text named triazole and strobilurin fungicides, a 3 to 5 day flowering window, and late planting as a tactic that lowers yield. None of this is in either source, and it was removed. (9) The text said surveillance networks exist on paper but sample sparsely across Africa. Neither source says this. The review says existing diagnostic tests are not convenient or reliable enough and that a real-time monitoring and surveillance system needs to be developed. The sentence now says that. (10) The text said quarantine rules blocked germplasm sharing during the 2016 Bangladesh outbreak and delayed research by at least one crop cycle. The review does not say this. It says sequence data from non-living samples can be shared across borders for a quarantined pest, and that open data sharing identified the origin of the Bangladesh outbreak within weeks. The sentence now says that. Confirmed against the sources and left as written: both titles in the Source line, the journal and the year 2020; yield loss of up to 100%; first identification in Brazil in 1985; Bangladesh in 2016 and Zambia in 2018; 2NS coming from Aegilops ventricosa and being eroded by new virulence groups; 13.5 million hectares and a 13% loss by 2050; BARI, CIMMYT and EMBRAPA as institutions working on the disease. The short title calls 2NS the only resistance gene. The review lists ten other genes but calls 2NS the only source confirmed in field experiments across wide environments, so the title was left as written. Not checked: the proposals in What Would Unlock Progress and in the entry points (a spore forecasting network, shared germplasm agreements, the comparison with influenza strain sharing) are suggestions and do not come from the sources. The Nature Climate Change study behind the EMBRAPA article is not cited here and was not opened. Genes untouched.

Reconciliation 2026-09-29 (re-sourcing): The editor asked for the claims removed in round 5 to be re-sourced. Three primary sources were fetched and read on 2026-09-29: the Nature Climate Change modeling study behind the EMBRAPA article, Pequeno et al. 2024, read at www.nature.com/articles/s41558-023-01902-2; Goddard et al. 2020 in BMC Plant Biology, read from the EMBRAPA repository copy of the publisher's PDF at www.alice.cnptia.embrapa.br/alice/bitstream/doc/1124870/1/s12870-020-02592-0.pdf; and Hossain 2022 in Frontiers in Microbiology, read at www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2022.983243/full. Citation strings were copied from the Nature "Cite this article" line, the PDF header, and the Crossref records. Restored: (a) The Problem Statement now says the spread is expected mainly in the tropics and the Southern Hemisphere, with South America the most affected region and African and South Asian countries increasingly vulnerable. Pequeno et al. write that "wheat blast is predicted to spread primarily in the tropics and Southern Hemisphere" and that "South America will be the most affected region, although African and South Asian countries will also be increasingly vulnerable." The original word "subtropical" was not restored because the source does not use it. (b) Why This Matters now says those regions are among the areas most vulnerable to the direct effects of climate change, where food security is already a considerable concern. Pequeno et al. write: "These areas are noted as some of the most vulnerable areas to the direct impacts of climate change, where food security is already a considerable concern." The original ranking of these zones as "among the most food-insecure regions globally" was not restored because the source does not say that. (c) The 13% loss is now tied to the highest greenhouse-gas emission scenario, RCP8.5, and to mid-century (2040–2070). Pequeno et al. write: "For the future scenarios (2041–2070), Representative Concentration Pathways 8.5, which represents the highest greenhouse gas emission scenario, was selected," and report a 69 million ton per year (13%) loss by mid-century. (d) BR 18-Terena is back in What's Been Tried: a Brazilian cultivar released in 1986, considered one of the best sources of blast resistance, widely used in Brazilian breeding, with the genetics of its resistance unknown until a 2020 study mapped nine quantitative trait loci. Goddard et al. write that BR 18-Terena "is considered one of the best sources of resistance to blast and has been widely used in Brazilian breeding programmes, however the underlying genetics of this resistance are unknown," that it has been used "since its release in 1986," and that "nine QTL associated with resistance at either the seedling or heading stage" were detected. (e) What Would Unlock Progress now says the mapped loci should allow genetic markers to track and combine that resistance in breeding, and could be of use in Bangladesh once trials there confirm it. Goddard et al. write that identifying these regions "should allow genetic markers to be developed to both track and combine these specific resistances within breeding programmes," that the QTL "could also be of potential use in Bangladesh," and that "additional trials in Bangladesh ... would be required to determine whether these resistances are suitable for that specific environment." The original claim of transfer into elite lines in Bangladesh, Zambia and Bolivia within 5 to 7 breeding cycles was not restored; no source gives those countries or that number. (f) The fungicide classes are back: chemical control has been shown to be ineffective when disease pressure is high, and resistance to strobilurin and triazole fungicides has been detected in Brazil. Hossain writes: "Chemical control techniques have been shown to be ineffective in controlling wheat blast when the disease pressure is high" and "resistance to strobilurin and triazole fungicides has already been detected in Brazil." (g) Planting dates are back at the source's scope: Pequeno et al. write that "it is recommended to avoid early planting in central Brazil and late planting in Bangladesh, as these periods coincide with high temperatures and RH." The original statements that these fungicides need timing within a 3 to 5 day flowering window and that late planting lowers yield were not restored; neither appears in the sources read. Searched and stayed out: the claim that the disease has spread "across southern Africa" (Pequeno et al. and Hossain both report Zambia in 2018 as the only African occurrence); the claim that fungicides fail because the plant limits how far fungicide can travel during flowering (not in Hossain, Pequeno et al. or Goddard et al.; the Cruz and Valent 2017 review could not be read because the publisher blocks automated access); the claim that wheat is the main source of calories for more than 2.5 billion people (the Erenstein et al. 2022 chapter "Global Trends in Wheat Production, Consumption and Trade" was read from the Internet Archive copy of the publisher's page and gives no such count; the figure appears only in secondary summaries); the claim that the 13% loss would push hundreds of millions of people below minimum calorie intake (no source gives a count of people); and the claims about sparse African surveillance sampling and a one-crop-cycle research delay from quarantine rules (no primary source found within the time allowed). Genes untouched.