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Yue Jin

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Yue Jin
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Yue Jin

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Start date: 2016 × End date: 2016 ×

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Now showing 1 - 5 of 5
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    Overview of stem rust epidemics in eastern Africa and races causing the epidemics
    (USDA, 2016) Hodson, D.P.; Yue Jin; Hovmoller, M.S.
    Publication
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    Nested association mapping of stem rust resistance in wheat using genotyping by sequencing
    (Public Library of Science, 2016) Bajgain, P.; Rouse, M.N.; Tsilo, T.J.; Macharia, G.; Bhavani, S.; Yue Jin; Anderson, J.
    We combined the recently developed genotyping by sequencing (GBS) method with joint mapping (also known as nested association mapping) to dissect and understand the genetic architecture controlling stem rust resistance in wheat (Triticum aestivum). Ten stem rust resistant wheat varieties were crossed to the susceptible line LMPG-6 to generate F6 recombinant inbred lines. The recombinant inbred line populations were phenotyped in Kenya, South Africa, and St. Paul, Minnesota, USA. By joint mapping of the 10 populations, we identified 59 minor and medium-effect QTL (explained phenotypic variance range of 1% – 20%) on 20 chromosomes that contributed towards adult plant resistance to North American Pgt races as well as the highly virulent Ug99 race group. Fifteen of the 59 QTL were detected in multiple environments. No epistatic relationship was detected among the QTL. While these numerous small- to medium-effect QTL are shared among the families, the founder parents were found to have different allelic effects for the QTL. Fourteen QTL identified by joint mapping were also detected in single-population mapping. As these QTL were mapped using SNP markers with known locations on the physical chromosomes, the genomic regions identified with QTL could be explored more in depth to discover candidate genes for stem rust resistance. The use of GBS-derived de novo SNPs in mapping resistance to stem rust shown in this study could be used as a model to conduct similar markertrait association studies in other plant species.
    Publication
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    Kenyan Isolates of Puccinia graminis f. sp. tritici from 2008 to 2014: virulence to SrTmp in the Ug99 race group and implications for breeding programs
    (American Phytopathological Society (APS), 2016) Newcomb, M.; Olivera Firpo, P.D.; Rouse, M.N.; Szabo, L.J.; Johnson, J.W.; Gale, S.; Luster, D.G.; Wanyera, R.; Macharia, G.; Bhavani, S.; Hodson, D.P.; Patpour, M.; Hovmoller, M.S.; Fetch, T.; Yue Jin
    Frequent emergence of new variants in the Puccinia graminis f. sp. tritici Ug99 race group in Kenya has made pathogen survey a priority. We analyzed 140 isolates from 78 P. graminis f. sp. tritici samples collected in Kenya between 2008 and 2014 and identified six races, including three not detected prior to 2013. Genotypic analysis of 20 isolates from 2013 and 2014 collections showed that the new races TTHST, TTKTK, and TTKTT belong to the Ug99 race group. International advanced breeding lines were evaluated against an isolate of TTKTT (Sr31, Sr24, and SrTmp virulence) at the seedling stage. From 169 advanced lines from Kenya, 23% of lines with resistance to races TTKSK and TTKST were susceptible to TTKTT and, from two North American regional nurseries, 44 and 91% of resistant lines were susceptible. Three lines with combined resistance genes were developed to facilitate pathogen monitoring and race identification. These results indicate the increasing virulence and variability in the Kenyan P. graminis f. sp. tritici population and reveal vulnerabilities of elite germplasm to new races.
    Publication
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    First Report of the Ug99 race group of Wheat Stem Rust, Puccinia graminis f. sp. tritici, in Egypt in 2014
    (American Phytopathological Society (APS), 2016) Patpour, M.; Hovmoller, M.S.; Shahin, A.; Newcomb, M.; Olivera Firpo, P.D.; Yue Jin; Luster, D.G.; Hodson, D.P.; Nazari, K.; Azab, M.
    Since the first detection of race TTKSK (Ug99) of Puccinia graminis f. sp. tritici in Uganda in 1998 (Pretorius et al. 2000), it has been a priority to track its further spread to other wheat growing areas. To date, 10 variants in the Ug99 race group have been detected in 12 countries, i.e., Uganda, Kenya, Ethiopia, Sudan, Tanzania, Eritrea, Rwanda, South Africa, Zimbabwe, Mozambique, Yemen and Iran (Patpour et al. 2015). In the 2014 crop season, the presence of virulence to Sr31 in Egypt was suspected based on preliminary field observations of high infection on sources of Sr31 planted as international stem rust trap nursery at 1) Sakha Agricultural Research Station in Kafrelsheikh (31.094059° N, 30.933899° E), 2) Al-Sharqia (30.601400° N, 31.510383° E), and 3) Nubaria (30.91464° N, 29.95543° E). At Sakha, wheat cv. PBW343 (carrying Sr31) was scored 30MS-S, and the monogenic line Benno Sr31/6*LMPG was scored 20MS-S at Al-Sharqia. Three samples from each of these lines were sent to the Global Rust Reference Center (GRRC, Denmark). At Nubaria, stem rust was observed on wheat cvs. Misr-1, Misr-2, Giza 168 and Giza 171, and infected samples were collected and sent under permit to the Foreign Disease-Weed Science Research Unit (MD, USA). Urediniospores of each sample were recovered on susceptible wheat cv. Morocco and McNair 701. Twenty-three and 11 single pustule isolates were derived and analyzed at GRRC and USDA-ARS Cereals Disease Laboratory, respectively, using 20 North American stem rust differential lines following standard race-typing procedure and infection type (IT) criteria determining virulence and avirulence (Jin et al. 2008). In addition, three supplemental tester lines of Siouxland (carrying Sr24+Sr31), Sisson (carrying Sr31+Sr36), and Triumph 64 (donor of SrTmp) were included to confirm virulence/avirulence to Sr24, Sr31, Sr36, and SrTmp. The experiments were repeated two to three times. Three races in the Ug99 race group were detected; TTKST (four isolates, IT 3+4 for Sr24, Sr31 and cv. Siouxland) from Al-Sharqia, TTKTK (13 isolates, IT 4 for Sr31, SrTmp and cv. Triumph 64) from Sakha, and TTKSK (2 isolates, IT 4 for Sr31) from Nubaria. This is the first confirmation of races in the Ug99 race group in Egypt, thereby extending the geographical distribution of Ug99-related races. Since Egypt may play a role as green-bridge for Puccinia graminis f. sp. tritici between East and North African countries and the wheat belts in the Middle East and Mediterranean region, the rust surveillance efforts should be intensified in affected countries as well as in neighboring regions.
    Publication
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    Emergence of virulence to SrTmp in the Ug99 race group of wheat stem rust, Puccinia graminis f. sp. tritici, in Africa
    (American Phytopathological Society (APS), 2016) Patpour, M.; Hovmoller, M.S.; Justesen, A.F.; Newcomb, M.; Olivera Firpo, P.D.; Yue Jin; Szabo, L.J.; Shahin, A.; Wanyera, R.; Habarurema, I.; Wobibi, S.; Hodson, D.P.
    The Ug99 race (TTKSK) of wheat stem rust was first detected in Uganda in 1998 (Pretorius et al. 2000) and since then seven additional variants have been reported, i.e., TTKSF, TTKST, TTTSK, TTKSP, PTKSK, PTKST, and TTKSF+ (Pretorius et al. 2012). In this study, 84 stem rust samples from the 2014 surveys of wheat fields in Africa (Kenya, 9; Uganda, 28; Rwanda, 41; and Egypt, 6) were sent to the Global Rust Reference Center (GRRC, Denmark) for race analysis. Puccinia graminis f. sp. tritici (Pgt) samples were recovered on cv. Morocco, and resulting urediniospores of 53 single-pustule isolates were inoculated onto 20 North American stem rust differential lines using standard procedures (Jin et al. 2008). The pathotyping was repeated in two or three independent experiments. Twelve of the derived isolates were also typed at the USDA-ARS Cereal Disease Laboratory (USA) for an independent confirmation. Among the Kenyan samples, four collected from Njoro (Central Rift, cvs. Robin and Kwale) and two from Ntulumeti and Olgilai (South Rift, cv. Robin), were typed as TTKTK. Race TTKTK was similar to TTKSK except for additional virulence to SrTmp (Infection Type 4). An additional single-pustule isolate derived from one sample from Njoro showed a high infection type on LcSr24Ag and CnsSrTmp, testers for Sr24 and SrTmp, respectively, and was typed as TTKTT. These isolates were also tested on Siouxland (PI 483469, Sr24+Sr31), Sisson (PI 617053, Sr31+Sr36), and Triumph 64 (CI 13679, donor of SrTmp) to confirm their virulence/avirulence combinations to Sr24, Sr31, Sr36, and SrTmp. Race TTKTK was also detected at two locations in Uganda (Rubaya and Muko in Kabale region) and at five locations in Rwanda (Kinigi, Rwerere, Rufungo, Gatebe and Kamenyo). Three isolates derived from stem rust samples collected on cv. PBW343 (carrying Sr31) in Sakha in the Nile Delta region in Egypt were also typed as TTKTK. In addition, DNA from isolates of race TTKTK were analyzed using a diagnostic qPCR assay (Ug99 RG stage-1, Szabo unpublished data), which confirmed that these samples belong to the Ug99 lineage. The identification of SrTmp virulence in the Ug99 race group in several countries in one year emphasizes the relevance of coordinated international surveillance efforts and utilization of diverse sources of resistance to control stem rust in wheat. Further studies are in progress to determine the detailed relationship of the newly emerged races and other Pgt isolates identified in the Ug99 group.
    Publication