Distribution, Epidemics dynamics and physiological races of wheat stem rust (Puccinia graminis f.sp. tritici Eriks and E. Henn) on irrigated wheat in the Awash River basin of Ethiopia

ABSTRACTWheat is one of the high value important major crops of the globe. However, wheat stem rust is considered one of the determinant threats to wheat production in Ethiopia and the globe. So this study was conducted with the objective to assess disease intensity, seasonal distribution dynamics, and genetic variability and to determine virulence spectrum of stem rust in the irrigated wheat areas of Ethiopia. A total of 137 wheat farms were evaluated from 2014/15 - 2019/20 in six districts of Awash River basin. Farm plots were assessed every 5 - 10 km interval with ‘X’ fashion, and data on disease incidence, severity, and healthy plants were scored with diseased wheat plant samples collection for stem rust race analysis. The seasonal trend of wheat stem rust disease was also compared to see the future importance of the diseases. The result revealed that the prevalence, incidence, and severity of stem rust were significantly varied among the different districts and seasons in the two regions. The survey results also indicated that about 71.7% of the wheat fields were affected by stem rust during the 2018/19 growing season. The overall incidence and mean severity of the disease during the same season were 49.02% and 29.27%, respectively. During 2019/20 about 63.7% of the wheat fields were affected by stem rust, which, however, the incidence (30.97%) and severity (17.22%) were lower than the previous season. Although the seasonal disease distribution was decreased, its spatial distribution was expanding into Lower Awash. The physiological and the genetic race analysis identified four dominant races (TTTTF, TKTTF TKKTF, and TTKTF) during 2018/19 and additional race (TKPTF) during 2019/20. Thus races are highly virulent and affect most of the Sr genes except Sr – 31 and Sr – 24. TTTTF and TKKTF are the widest virulence spectrum which affects 90% of the Sr genes. Thus, it can be concluded that the spatial and seasonal distribution of the disease was expanding. Moreover, most of the races were similar with rain-fed production, and thus care must be given for effective management of the diseases to both agro-ecologies. Therefore, these findings provide inputs or insight for breeders to think about the breeding programs in their crossing lines and wheat producers to reduce the damage of the disease in the irrigated ecologies.ETHICAL STATEMENTThus, surveys were conducted with the lateral aim of rust epidemics early warning and monitoring support program in the Awash River basin. Samples for this study were collected from farmers’ fields of the irrigated production areas in the Awash River basin. The disease was an air-borne disease that is difficult to contain. Still, we give maximum care during surveying through spore-free through self-sanitation after Pgt infested field observation to minimize induced disease dissemination to the communities in the production areas that no specific permissions were required for these locations. Field sites are on public access, and P. graminis f. sp. tritici is already an air-born pathogen that doesn’t need special protection kinds. This work was our study experience in the endeavor in irrigated wheat technology dissemination.

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Distribution, dynamics, and physiological races of wheat stem rust (Puccinia graminis f.sp. tritici) on irrigated wheat in the Awash River Basin of Ethiopia

PLoS ONE ◽

10.1371/journal.pone.0249507 ◽

2021 ◽

Vol 16 (9) ◽

pp. e0249507

Author(s):

Nurhussein Seid Yesuf ◽

Sileshi Getahun ◽

Shiferaw Hassen ◽

Yoseph Alemayehu ◽

Kitessa Gutu Danu ◽

...

Keyword(s):

River Basin ◽

Stem Rust ◽

Disease Incidence ◽

Puccinia Graminis ◽

Rust Disease ◽

Wheat Stem Rust ◽

Awash River Basin ◽

Irrigated Wheat ◽

Virulence Spectrum ◽

Race Analysis

Wheat is one of the high-value major crops in the world. However, wheat stem rust is considered one of the determinant threats to wheat production in Ethiopia and the world. So this study was conducted to assess the disease intensity, seasonal distribution dynamics pattern, the genetic variability of Puccinia graminis f. sp. tritici, and to determine the virulence spectrum in the irrigated ecology of the Awash River Basin. Totally 137 wheat farms were evaluated, from 2014/15–2019/20 in six districts representing the Upper, Middle, and Lower Awash River Basin. Farm plots were assessed, in every 5–10 km intervals, with ’X’ fashion, and data on disease incidence, severity, healthy plants were counted and recorded. Diseased samples were collected from the diseased wheat stem by Puccinia graminis physiological and genetic race analysis. The seasonal trend of stem rust disease progress showed its importance to infer the future progresses of the disease for the country’s potential production plan of irrigated wheat. The result revealed that the disease prevalence, disease incidence, and severity were significantly varied; among the different districts and seasons in the two regions. The survey results also indicated that about 71.7% of the wheat fields were affected by stem rust during the 2018/19 growing period. The disease’s overall incidence and mean severity during the same season were 49.02% and 29.27%, respectively. In 2019/20, about 63.7% of the wheat fields were affected by stem rust, disease incidence 30.97%, and severity 17.22% were lower than the previous season. In 2019/20, even though seasonal disease distribution decreased, the spatial distribution was expanding in Afambo and Dubti districts. Four, stem rust dominant races were identified (TTTTF, TKTTF TKKTF, and TTKTF) by physiological and genetic race analysis during 2018/19 and one additional race (TKPTF) in 2019/20, production year. The result indicated that the races are highly virulent and affect most Sr genes except Sr31 and Sr24. From the race analysis result, TTTTF, and TKKTF have the broadest virulence spectrum race, which affects 90% of the Sr genes. Generally, we can conclude that the spatial and seasonal distribution of the disease is expanding. Most of the races in the irrigated areas in the Basin were similar to that of rain-fed wheat production belts in Ethiopia, so care must be given, to effective management of the diseases, in both production ecologies towards controlling the spore pressure than race variability. Therefore, these findings provide inputs for wheat producers to reduce the spread and disease’ damage in the irrigated ecologies of Ethiopia. Also, it gives an insight for breeders to think about the breeding program in their crossing lines.

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Characterization of Wheat Monogenic Lines with Known Sr Genes and Wheat Lines with Resistance to the Ug99 Race Group for Resistance to Prevalent Races of Puccinia graminis f. sp. tritici in China

Plant Disease ◽

10.1094/pdis-12-19-2736-re ◽

2020 ◽

Vol 104 (7) ◽

pp. 1939-1943

Author(s):

Xian Xin Wu ◽

Qiu Jun Lin ◽

Xin Yu Ni ◽

Qian Sun ◽

Rong Zhen Chen ◽

...

Keyword(s):

Food Security ◽

Stem Rust ◽

Adult Plant ◽

Puccinia Graminis ◽

Wheat Cultivars ◽

Wheat Stem Rust ◽

Wheat Improvement ◽

Wheat Lines ◽

Sr Genes

Wheat stem rust, caused by Puccinia graminis f. sp. tritici, is one of the most serious fungal diseases in wheat production, seriously threatening the global supply of wheat and endangering food security. The present study was conducted to evaluate wheat monogenic lines with known Sr genes to the most prevalent P. graminis f. sp. tritici races in China. In addition, wheat lines introduced from the International Maize and Wheat improvement Center (CIMMYT) with resistance to the Ug99 race group were also evaluated with the prevalent Chinese P. graminis f. sp. tritici races. The monogenic lines containing Sr9e, Sr21, Sr26, Sr31, Sr33, Sr35, Sr37, Sr38, Sr47, and SrTt3 were effective against races 21C3CTTTM, 34C0MRGSM, and 34C3MTGQM at both seedling and adult-plant stages. In contrast, monogenic lines containing Sr6, Sr7b, Sr8a, Sr9a, Sr9b, Sr9d, Sr9f, Sr9g, Sr13, Sr16, Sr18, Sr19, Sr20, Sr24, Sr28, Sr29, and Sr34 were highly susceptible to these races at both seedling and adult-plant stages. Lines with Sr5, Sr10, Sr13, Sr14, Sr15, Sr17, Sr21, Sr22, Sr23, Sr25, Sr27, Sr29, Sr30, Sr32, Sr36, and Sr39 were resistant to one or more of the tested races. Among the 123 CIMMYT lines, 38 (30.9%) showed varying levels of susceptibility to Chinese P. graminis f. sp. tritici races. The results should be useful for breeding wheat cultivars with resistance to stem rust.

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Virulence Spectrum of Wheat Stem Rust (Puccinia graminis f.sp.tritici) in the Eastern Showa of Central Ethiopia

Advances in Crop Science and Technology ◽

10.4172/2329-8863.1000s1-008 ◽

2015 ◽

Vol s1 ◽

Author(s):

Abiyot Lemma Getaneh Woldeab

Keyword(s):

Stem Rust ◽

Puccinia Graminis ◽

Wheat Stem Rust ◽

Central Ethiopia ◽

Virulence Spectrum

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Detection of Variants of Wheat Stem Rust Race Ug99 (Puccinia graminis f. sp. tritici) in Zimbabwe and Mozambique

Plant Disease ◽

10.1094/pdis-04-11-0300 ◽

2011 ◽

Vol 95 (9) ◽

pp. 1188-1188 ◽

Cited By ~ 10

Author(s):

F. Mukoyi ◽

T. Soko ◽

E. Mulima ◽

B. Mutari ◽

D. Hodson ◽

...

Keyword(s):

South Africa ◽

Stem Rust ◽

Genetic Similarity ◽

Puccinia Graminis ◽

Wheat Stem Rust ◽

The North ◽

Ssr Analysis ◽

Kwazulu Natal ◽

Fungal Dna ◽

Race Analysis

The migration of Ug99 variants of Puccinia graminis f. sp. tritici is of concern to global wheat production (1). Seven races have been characterized in the Ug99 lineage (3), three of which occur in South Africa (4). During surveys of wheat fields for Ug99 in Zimbabwe and Mozambique in August and September 2010, high stem rust severities were found at Chiredzi, Chisumbanje, and Birchenough in Zimbabwe and at Rotanda in Mozambique. Stem rust was widespread in the lowlands (<800 m above sea level) of Zimbabwe and trace amounts were present in the mid-altitude areas. In Mozambique, stem rust was only observed at Rotanda (sample Moz1001). Collections from Chiredzi (samples Zim1004 and Zim1005), Chisumbanje (Zim1006), and Birchenough (Zim1009 and Zim1010) yielded viable urediniospores for infection studies. According to race analysis conducted on seedlings of the North American stem rust differential set (2) in a greenhouse at 18 to 25°C, Zim1005 and Zim1006 were typed as PTKST and Zim1004 and Zim1009 as TTKSF. Both TTKSF and PTKST were detected in the Zim1010 sample. Race analysis experiments were conducted three times. Urediniospores of isolate Moz1001 were not viable in infection studies, but yielded fungal DNA for simple sequence repeat (SSR) analysis. Using eight selected SSR primer combinations (4), all six isolates clustered within the Ug99 lineage. Isolates Zim1005, Zim1006, Zim1009, Zim1010, and Moz1001 and the stem rust control races TTKSF, TTKSK, and PTKST grouped into two main clusters, with Zim1009 and Zim1010 clustering together and sharing 88% similarity with the rest of the isolates. Zim1005 and Zim1006 were identical to TTKSF and TTKSK, respectively. Zim1004 shared 96% genetic similarity with the TTKSP control, with these two sharing 74% genetic similarity with the remaining isolates. The SSR data correlated with the infection data, except for Zim1004, which was typed as TTKSF but clustered close to TTKSP. Wheat cvs. SC Nduna, SC Shine, SC Stallion, SC Smart, Kana, Insiza, and Dande are predominant in Zimbabwe. Cv. SC Stallion and other unidentified cultivars were susceptible to P. graminis f. sp. tritici in the field in Zimbabwe. In Mozambique, the tall, local cv. Sitsonko was susceptible to P. graminis f. sp. tritici but no infections were observed on SC Nduna or SC Shine. The similarity in P. graminis f. sp. tritici races in Zimbabwe, South Africa, and Mozambique suggests that inoculum is exchanged within the region and explains the detection of race PTKST in South Africa in 2009. Trajectory models showed winds originating at Birchenough in October 2009, where stem rust was observed, passing directly over KwaZulu-Natal, South Africa within 48 to 72 h. Race PTKST was confirmed from collections in KwaZulu-Natal in November 2009 (4). The confirmation of Sr31 virulence in race PTKST in Zimbabwe is important because it provides new geographical records for an Ug99-related race and puts Southern African cultivars with 1B.1R resistance at risk. References: (1) D. Hodson. Euphytica 179:93, 2011. (2) Y. Jin et al. Plant Dis. 92:923, 2008. (3) R. F. Park et al. Euphytica 179:109, 2011. (4) B. Visser et al. Euphytica 179:119, 2011.

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Identification of Wheat Gene Sr35 That Confers Resistance to Ug99 Stem Rust Race Group

Science ◽

10.1126/science.1239022 ◽

2013 ◽

Vol 341 (6147) ◽

pp. 783-786 ◽

Cited By ~ 162

Author(s):

Cyrille Saintenac ◽

Wenjun Zhang ◽

Andres Salcedo ◽

Matthew N. Rouse ◽

Harold N. Trick ◽

...

Keyword(s):

Stem Rust ◽

Coiled Coil ◽

Puccinia Graminis ◽

Yield Losses ◽

Wheat Stem Rust ◽

Polyploid Wheat ◽

A Genome ◽

Wheat Gene ◽

Production Areas ◽

Wheat Rust

Wheat stem rust, caused by Puccinia graminis f. sp. tritici (Pgt), is a devastating disease that can cause severe yield losses. A previously uncharacterized Pgt race, designated Ug99, has overcome most of the widely used resistance genes and is threatening major wheat production areas. Here, we demonstrate that the Sr35 gene from Triticum monococcum is a coiled-coil, nucleotide-binding, leucine-rich repeat gene that confers near immunity to Ug99 and related races. This gene is absent in the A-genome diploid donor and in polyploid wheat but is effective when transferred from T. monococcum to polyploid wheat. The cloning of Sr35 opens the door to the use of biotechnological approaches to control this devastating disease and to analyses of the molecular interactions that define the wheat-rust pathosystem.

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Physiological Races and Virulence Diversity of Puccinia graminis pers. f. sp. tritici eriks. & e. Henn. on Wheat in Tigray Region of Ethiopia

International Journal of Phytopathology ◽

10.33687/phytopath.002.01.0023 ◽

2013 ◽

Vol 2 (1) ◽

pp. 01-07

Author(s):

Teklay Abebe ◽

Woubit Dawit ◽

Getaneh Woldeab

Keyword(s):

Stem Rust ◽

Hot Spot ◽

Gene Pyramiding ◽

Phenotypic Characterization ◽

Puccinia Graminis ◽

Wheat Stem Rust ◽

Tigray Region ◽

Differential Hosts ◽

Sr Genes ◽

Virulence Diversity

Wheat stem rust caused by Puccinia graminis f. sp. tritici is a disease that causes complete annihilation of wheat crops over wide areas during epidemic years. The highland of Ethiopia is considered as a hot spot area for the development of stem rust complex. Hence, this study was carried out to detect the virulence diversity of P. graminis f. sp. tritici in Southern Tigray. The findings of this paper were based on race analysis through inoculation of stem rust populations, isolation and multiplication of single-pustule of the pathogen and race determination by inoculating on stem rust differential hosts. The phenotypic characterization of P. graminis f. sp. tritici resulted in identification of 20 races from 32 isolates, which included the most prevalent races TTSNK, RRJJC and HRJJC with a frequency of 9.4% each and the most virulent races TTKSK and TTSSK each making 85% of Sr genes ineffective. Three important races (TTSSK, TTSNK and RRTTF) are new to the study area and the country (Ethiopia) as a whole putting a significant wheat proportion at risk. Among 20 wheat stem rust differential hosts, four were found effective for 75% and more of the races identified. Differential host carrying Sr24 was effective to all, while gene SrTmp was effective to 90% of the races followed by Sr17 and Sr31 each effective for 75%. In contrast, differential hosts carrying SrMcN, Sr9b, Sr9g and Sr10 were ineffective to 96.9, 93.8, 87.5 and 81.2% of the isolates tested, respectively. Thus, use of effective Sr genes such as Sr24 and SrTmp in single cultivar through gene pyramiding has paramount importance as the additive effects of several genes gives the cultivar a wider base stem rust resistance along with periodic race survey.

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Characterization of Synthetic Wheat Line Largo for Resistance to Stem Rust

G3 Genes|Genome|Genetics ◽

10.1093/g3journal/jkab193 ◽

2021 ◽

Author(s):

Jyoti Saini Sharma ◽

Megan Overlander ◽

Justin D Faris ◽

Daryl L Klindworth ◽

Matthew N Rouse ◽

...

Keyword(s):

Stem Rust ◽

Recombinant Inbred Lines ◽

Resistance Breeding ◽

Synthetic Hexaploid Wheat ◽

Genetic Linkage Analysis ◽

Wheat Line ◽

Wheat Stem Rust ◽

Wheat Varieties ◽

Seedling Resistance ◽

Sr Genes

Abstract Resistance breeding is an effective approach against wheat stem rust caused by Puccinia graminis f. sp. tritici (Pgt). The synthetic hexaploid wheat line Largo (pedigree: durum wheat ‘Langdon’ × Aegilops tauschii PI 268210) was found to have resistance to a broad spectrum of Pgt races including the Ug99 race group. To identify the stem rust resistance (Sr) genes, we genotyped a population of 188 recombinant inbred lines developed from a cross between the susceptible wheat line ND495 and Largo using the wheat Infinium 90 K SNP iSelect array and evaluated the population for seedling resistance to the Pgt races TTKSK, TRTTF, and TTTTF in the greenhouse conditions. Based on genetic linkage analysis using the marker and rust data, we identified six quantitative trait loci (QTL) with effectiveness against different races. Three QTL on chromosome arms 6AL, 2BL, and 2BS corresponded to Sr genes Sr13c, Sr9e, and a likely new gene from Langdon, respectively. Two other QTL from PI 268210 on 2DS and 1DS were associated with a potentially new allele of Sr46 and a likely new Sr gene, respectively. Additionally, Sr7a was identified as the underlying gene for the 4AL QTL from ND495. Knowledge of the Sr genes in Largo will help to design breeding experiments aimed to develop new stem rust-resistant wheat varieties. Largo and its derived lines are particularly useful for introducing two Ug99-effective genes Sr13c and Sr46 into modern bread wheat varieties. The 90 K SNP-based high-density map will be useful for identifying the other important genes in Largo.

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