All Russian Research Institute of Biological Plant Protection
Irina Petrovna Matveeva
Yellow rust caused by Puccinia striiformis West. is a harmful and dangerous disease in the south of Russia. Yield losses under optimum conditions on highly susceptible varieties can vary from 10 to 100%. During the growing season of 2017, cool weather with constant precipitation from the third decade of April to the first decade of June contributed to the intensive development of the pathogen. Surveys of the main winter wheat production areas in five agroclimatic zones of the region revealed that yellow rust was prevalent in all areas. The maximum development of P.striiformis was observed in southern submontane and western Priazovsky agroclimatic zones. Some varieties such as Grom, Yuka, Tanya, Anka had losses to yellow rust of up to 30-40 %. In the central and northern agroclimatic zones, the losses averaged 5%, whereas in the dry eastern steppe zone losses were only up to 1%. The build up of yellow rust inoculum in the region raises concerns that in 2018, under favorable weather conditions in spring, winter wheat crops could be infected with the disease, especially in the wetter agroclimatic zones.
Egerton University Njoro, Kenya
Ruth Wanyera, James Owuoche, Julian Rodriguez, Annemarie Justesen, Lesley Lesley, Sridhar Bhavani, Cristobal Uauy, Mogens Hovmøller
Emergence of new virulent races of Puccinia striiformis f. sp. tritici (Pst) to stripe (yellow) rust resistance genes in wheat (Triticum aestivum L.) has historically resulted in severe yield losses worldwide. We conducted a study to characterize the virulence profiles of Pst races prevalent in Kenya from historic (1970-1992) and recent collections (2009-2014). Pst isolates collected during surveys in Kenya were characterized at the Global Rust Research Centre (GRRC), Denmark. Yellow rust differential sets (wheat lines with known Yr resistance genes), and strain-specific sequence-characterized-amplified-region (SCAR) markers were used to group the Pst isolates as Pst1 or Pst2. Virulence to Yr1, Yr2, Yr3,Yr6, Yr7, Yr8, Yr9, Yr17, Yr25, Yr27, and the seedling resistance in AvocetS were detected. A total of 12 virulence profiles /races were detected in isolates obtained during 1970 to 1992, while six races were detected from samples collected between 2009 to 2014. In both periods, races with virulence profiles Yr2, Yr6, Yr7, Yr8, Yr25, Yr27, Avs and Yr2, Yr6, Yr7, Yr8, Yr17, Yr25, AvS were common. The SCAR results revealed that both Pst1 and Pst2 strains were present in the Pst isolates tested, Pst1 even in isolates from the 1970s. Additional isolates were also identified with neither Pst1 nor Pst2 profiles. From our findings, race analysis is key to understand the race diversity and pre-breeding efforts for effective resistance gene deployment.
The University of Agriculture, Peshawar, Pakistan
Muhammad,Khan, Safi, Kathi, Zahoor, Swati, Manzoor, Hussain, Annemarie, Justesen, Muhamamd, Imtiaz, , , , , , , , , , , , , , , , , ,
Considering the importance of wheat rust diseases in Pakistan and the recent identification of yellow rust pathogen (Puccinia striiformis f. sp. tritici) centre of diversity in Pakistan, the present study was designed to assess the status of three wheat rusts across the country during 2015-16 and 2016-17 and analyze the population structure of P. striiformis f. sp. tritici . A total of 451 fields (from 68 districts) were surveyed during 2016 and 480 fields (from 69 districts) during 2017. A high yellow rust pressure was present during 2016 throughout Pakistan, while it was predominant only in the Northern half during 2017. Leaf rust was present in the central part of the country, while stem rust was only found in the south. In Sindh province (located in the south), yellow rust was reported unexpectedly with high severity (>60%) on varieties like Kiran and Galaxy during both the years. A set of 513 samples of P. striiformis were genotyped with microsatellite markers to assess the population diversity and spatial structure. and infer on the cause of epidemics in the Sindh province. Population genetics analyses confirmed a recombinant population structure across all locations except the Sindh province, where relatively lower diversity and lack of recombination signature was revealed. At least five genetic groups were identified in the overall population, which were found across all locations, except Sindh province where one of the genetic groups was predominant. The P. striiformis population from Sindh province with low diversity that caused unexpected epidemics in a relatively warmer region needs to be further investigated for specific adaptation traits. Our results confirmed the high diversity across Pakistan, which lies in the Himalayan centre of diversity of the pathogen. This high diversity was present in locations without the presence of alternate host (Berberis spp.) and could potentially be associated with regular migrants from the Berberis zone into the whole country.
Crop and Horticultural Science Research Department, Ardabil Agricultural and Natural Resources Research and Education Center, Ag
Yellow (stripe) rust caused by Puccinia striiformis f. sp. tritici is the most devastating disease of bread wheat (Triticum aestivum) in the world. A wide range of virulent yellow rust pathotypes is evolving in different regions of the world causing the breakdown of widely utilized sources of resistance in wheat. Hence, the knowledge of virulence factors of pathogen and determining of effective resistance genes in the region will enable breeders to target those useful genes in their breeding programs. During cropping seasons of 2015-2016 and 2016-2017, virulence of the wheat yellow rust was investigated by planting differential cultivars and isogenic lines in a yellow rust trap nursery in Ardabil, northwest of Iran . Results showed stripe rust infections on some cultivars carrying Yr genes such as Yr1, Yr3, and Yrsp previously known to be resistant. The virulence spectrum of race population in Ardabil was identical to the Warrior race or its variants which is different from characterized races in Ardabil by carrying virulence combination for Yr1, Yr3, Yr17, Yr32, and YrSP and is avirulent on Yr8 and Yr27. Except for Yr8, Yr17 and Yr27, the common races in Ardabil are generally avirulent on Yr1, Yr3, and YrSP. This is the first report of race population in Ardabil (Iran) which is similar to the Warrior race or its variants.
Food and Agriculture Organization of the UN
Munira Otambekova, Bahromiddin Husenov, Alexei Morgounov
Wheat as a staple food crop in Tajikistan plays a crucial role for food security of population. However its production is threatened by number of limiting factors, and among them wheat rusts are most devastating disease.
Close collaboration of local scientists and breeders was established with International Agricultural Research Centers, including CIMMYT and ICARDA since early 2000. In the result, a number of high yielding and rust resistant varieties were released in Tajikistan that occupy presently about 40% of total wheat area.
Among the major breeding objectives selection of varieties with high resistance to wheat rusts, especially yellow rust considered as a priority task. The following new varieties originated from CIMMYT international nurseries were released in the country in past years, which bear high resistance to yellow rust: Sarvar (CHEN\AEGILOPS SQUARROSA (TAUS0//BCN/3/BAV92), Yusufi (SOROCA), Vahdat (VORONA SN079), Isfara (SW89.5181/KAUZ), Fayzbaksh (TAM200.KAUZ) and Shokiri (SHARK/F4105W2.1).
During the last three years eight new varieties were submitted for official testing, and two of them already are released in 2017 (Murodi and Durakhshon) and remaining ones are under official testing. The varieties and their origin are followings: Murodi (CHEN/AE.SQ//WEAVER/3/SSERI1), Durakhshon (ATTILA/3*BCN*2//BAV92), Kamol (PYN/BAU//LAGOS-19/3/ID800994.W/VEE), Zarnisor (CROC_1/AE.SQUARROSA(205)//BORL95/3/2*MILAN), Ganj (NAC/TH.AC//3*PVN/3/MIRLO/BUC/4/2*PASTOR), Mehrgon (SAAR/WAXWING), Sipar (FRET 2*2/4/SNI/TRAP #1/3/KAUZ*2/TRAP//KAUZ/5) and Lochin (PJN/BOW//OPATA*2/3/CROC_1/AE.SQ.(224)).
Ayub Agricultural Research Institute, Faisalabad, Pakistan
Muhammad,Idrees, Faqir, Muhammad, Arshad, Mehmood, Majid, Nadeem, Saleem-ur, Rehman, Makhdoom, Hussain, Javed, Ahmad, , , , , , , , , , , , , , , ,
Under changing climatic conditions, the emergence of new diseases or new races of existing diseases is a serious threat to global wheat production. Particularly, the presence of wheat blast in Bangladesh and stem rust race Ug99 in Iran, created a fearsome and intractable situation for Pakistan. A study was planned for monitoring and surveillance of the wheat blast and rust pathogens in wheat growing districts of Punjab, Pakistan during the cropping season 2016-17 as vigilance program. During the survey, one hundred and seventy one wheat fields of upper and central Punjab region were monitored and two types of Rusts (Leaf Rust & Yellow Rust) were recorded in varying intensity on different varieties of wheat. Out of 171 locations 86 spots were free from both types of rusts i.e. Leaf Rust & Yellow Rust, while the remaining locations were found to be infected with both leaf and yellow rust. However, all the surveyed fields were free from the stem rust infestation. Among the infected fields, 23 were infected by Leaf Rust while 63 fields were infected by Yellow Rust.The susceptible type of rust attack was noticed on old/ banned/ unapproved wheat varieties. Moderately resistant to resistant reaction was observed on newly approved varieties. The rust infected samples having S or MS type infection were collected for race analysis. Similarly, blast suspected samples were analyzed in laboratory and none of the tested samples showed the presence of wheat blast pathogen, which indicates no need to panic but vigilant in future.
Aleppo University, Aleppo , Syria
Bassam,Souliman, Naem, Al-Housien, Mohammad Shafick, Hakiem, Miloudi.M, Nachit, , , , , , , , , , , , , , , , , , , , , ,
Wheat yellow rust, caused by Puccinia triticina f. sp. tritici, is the major problem in wheat production in most parts of West Asia. Monitoring of the pathogen virulence factors and their changes provides basic information for the development of an early warning system. Wheat yellow rust has become increasingly important in the Syrian central and coastal areas during the last three years, The objective of this study was to identify races of the pathogen. Yellow rust samples collected at sites in the central and the coastal plains, were analyzed on differential host genotypes with known seedling resistance genes. According to the results of race determination, races 230E150, 166E150, 230E142 and 462E128 were identified. The race 462E128 designated the Warrior race, was identified at several sites across the Syrian central plains at the end of the 2017 growing season (early and Mid-May) when yellow rust exploded suddenly on a number of varieties, despite their previous high resistance ratings. The infections rapidly reached significant levels, in spite of the high temperature (up to 33?C) and the absence of rainfall or irrigation. This new virulent race (462E128) has been able to attack wheat lines with several major resistance gene(s) including: Spaldings Prolific (SP), Yr 3+4, Triticum spelta (Yr5), which remained effective until 2016 in Syria, Virulence to lthe resistance genes Yr1, Yr2, Yr2+, Yr3V, Yr3ND, Yr4+, Yr6, Yr6+, Yr7, Yr7+, Yr9, Yr9+, Yr11, Yr12, Yr18, Yr24, Yr26 Spaldings Prolific (YrSP), Anza (YrA+) Spaldings Prolific (SP), Yr 3+4, Triticum spelta (Yr5) and Selkirk (YrSK) was also found. Virulence to Carstens V (CV), Yr 15/6* Avocet S and Yr 5/6* Avocet S; was not found. According to our findings, the Warrior race has increased in frequency within the mix of yellow rust races in these areas in Syria . It is expected that the Warrior yellow rust race will cause damage on resistant wheat cultivars in 2018.
University of Minnesota
Michael Pumphrey, Matthew Rouse
Stem rust of wheat caused by the fungal pathogen Puccinia graminis f. sp. tritici historically caused major yield losses of wheat worldwide. To understand the genetic basis of stem rust resistance in contemporary North American spring wheat, genome-wide association analysis was conducted on 250 elite lines. The lines were evaluated in separate nurseries each inoculated with a different P. graminis f. sp. tritici race for three years (2013, 2015 and 2016) at Rosemount, Minnesota. The lines were also challenged with the same four races at the seedling stage in a greenhouse facility at the USDA-ARS Cereal Disease Laboratory. A total of 22,310 high-quality SNPs obtained from the Infinium 90,000 SNPs chip were used to perform association analysis. Markers strongly associated with resistance to the four races at seedling and field environments were identified. At the seedling stage, the most significant marker-trait associations were detected in the regions of known major genes (Sr6, Sr7a and Sr9b) except for race QFCSC where a strong association was detected on chromosome arm 1AL. Markers presumably linked to Sr6 and Sr7a were associated with both seedling and field resistance to specific races. A field resistance QTL on chromosome arm 2DS was detected for response to races RCRSC and TPMKC. A QTL specific to field resistance was detected for QFCSC and TPMKC on 2BL. The markers that showed strong association signals may be useful to pyramid and track race-specific stem rust resistance genes in wheat breeding programs. We postulated the presence of Sr2, Sr6, Sr7a, Sr8a, Sr9b, Sr11, Sr12, Sr24, Sr25, Sr31, and Sr57 (Lr34) in this germplasm based on phenotypic and marker data. We found that combinations of genes conferring resistance to specific P. graminis f. sp. tritici races accounts for the prevalent stem rust resistance in North American spring wheat.
University of Minnesota
Bedada,Girma, Bekele, Hundie, Endale, Hailu, Getaneh, Wonderufael, Bekele, Abeyo, Ayele, Badebo, Pablo, Olivera, Yue, Jin, Gordon, Cisar, Matthew, Rouse, , , , , , , , , ,
Wheat stem rust, caused by Puccinia graminis f. sp. tritici (Pgt), is a significant disease limiting wheat yield in Ethiopia. Wheat varieties such as 'Digalu' with single major-effect stem rust resistance genes have not exhibited durable resistance in Ethiopia. Identifying wheat lines with adult plant resistance (APR) has been proposed as a strategy to select for durable resistance. Our objective was to test the hypothesis that APR to stem rust is non-race-specific. We selected 31 wheat lines (including 10 durum and 21 bread wheat lines) that were susceptible as seedlings to Pgt races TTKSK, TKTTF, and TRTTF. These 31 wheat lines and Digalu were evaluated in 2014 and 2015 at the Kulumsa Agricultural Research Center, Ethiopia. The lines were planted in 1 m rows and replicated twice in separate single-race-inoculated nurseries. The three single-race nurseries inoculated with Pgt races TTKSK, TKTTF, and TRTTF were separated by at least 100 m and included selective spreaders. Plot yield, thousand kernel weight (TKW), and visual disease responses were measured for each plot. We used a least-squared means test to detect differences in coefficient of infection and TKW of each line across paired race comparisons. Lines 'Park', 'CI11469', and 'CI12818' displayed significantly different coefficient of infections between races TTKSK and TRTTF. For CI11469 and CI12818, this difference was validated by significant differences in TKW. Significant differences in TKW were also detected between various race comparisons for 'ETHBW019', 'CI14798', 'CI15159', 'CI14618', and 'CI14094'. Our data demonstrated that APR in the selected germplasm was largely non-race-specific, but there were exceptions where race-specificity of APR was detected. These results have implications for resistance breeding and monitoring: testing of breeding material against prevalent Pgt races in target environments, not relying only on hotspot screening locations, and careful monitoring of deployed APR varieties are all warranted.
State Key Laboratory of Crop Stress Biology in Arid Areas, Northwest A&F University, Yangling 712100, Shaanxi, China
Hui,Liu, Guangwei, Xing, Xiaojun, Nie, Song, Weining, , , , , , , , , , , , , , , , , , , , , ,
RNA editing is an important way to convert cytidine (C) to uridine (U) at specific sites within RNA molecules at a post-transcriptional level in the chloroplasts of higher plants. Although it has been systematically studied in many plants, little is known about RNA editing in the wheat D genome donor Aegilops tauschii L. Here, we investigated the chloroplast RNA editing of Ae. tauschii and compared it with other wheat relatives to trace the evolution of wheat. Through bioinformatics prediction, a total of 34 C-to-U editing sites were identified, 17 of which were validated using RT-PCR product sequencing. Furthermore, 60 sites were found by the RNA-Seq read mapping approach, 24 of which agreed with the prediction and six were validated experimentally. The editing sites were biased toward tCn or nCa trinucleotides and 50-pyrimidines, which were consistent with the flanking bases of editing sites of other seed plants. Furthermore, the editing events could result in the alteration of the secondary structures and topologies of the corresponding proteins, suggesting that RNA editing might impact the function of target genes. Finally, comparative analysis found some evolutionarily conserved editing sites in wheat and two species-specific sites were also obtained. This study is the first to report on RNA editing in Aegilops tauschii L, which not only sheds light on the evolution of wheat from the point of view of RNA editing, but also lays a foundation for further studies to identify the mechanisms of C-to-U alterations.