CSK Himachal Pradesh Agricultural University, Palampur, India
Aashima Bhateja, Ravi Sharma, Vijay Rana, Hanif Khan
Wheat crop is attacked by three rust diseases of which stripe rust, caused by Puccinia striiformis f. sp. tritici and leaf rust, caused by Puccinia triticina, are the most common causing greater yield losses. Thirty genotypes were studied for (APR) adult plant resistance and were evaluated in field conditions and controlled conditions. HPW 373, VW 20145, VL 3002, RKVY 231, VL 907, PBW 698 and HS 507 were found to be highly resistant to yellow rust at both seedling and adult plant stages. While, genotypes HS 490, HPW 314, HPW 360, RKVY 133, Raj 4362, DBW 113 and HPW 403 showing very low AUDPC values were found to be moderately resistant under field conditions. These lines are suggested for use in breeding program and some are in network trials for their direct release. Inheritance studies were carried out to decipher the genetics of seedling rust resistance in elite germplasm line HPW 373. The F2s were evaluated for seedling resistance against yellow rust (46S119, 78S84) and leaf rust (77-5-North American equivalent THTTM) races. Resistance in HPW 373 is controlled by single dominant gene against leaf rust (77-5) and stripe rust (78S84). Against stripe rust (46S119), resistance of HPW 373 is controlled by recessive gene. The findings are expected to contribute towards enriching diversity for leaf and stripe rust resistance in bread wheat improvement programmes.
ICAR-IARI, New Delhi
Sudheer Kumar, Subhash Chandar Bhardwaj, Om Prakash Gangwar, Vaibhav Kumar Singh, Mukesh Kumar Pandey, Jaspal Kaur, Ashwani Kumar Basandrai, Deepshikha, Pradeep Singh Shekhawat, R.K. Devlash, V.K. Rathee
In India, wheat crop is a major contributor to the agricultural economy of India, occupying 30.7 mha area with 98.38 mt production. Stripe or yellow rust is a constraint to wheat production on about 12.0 m ha in the Northern Hills and North Western region of India. Varieties resistant at the time of release become susceptible usually within a few years due to new pathogen races. The present study conducted in 2015-16 was undertaken to identify stripe rust resistant genotypes among a set of 146 advanced breeding lines and popular cultivars. All genotypes were planted in two replications in northern India at ten locations viz., Karnal, Hisar (Haryana), Ludhiana, Gurdaspur (Punjab), Malan, Bajoura, Dhaulakuan (Himachal Pradesh), Pantnagar (Uttarakhand), Durgapura (Rajasthan), Jammu (J & K) and Delhi. After every 20 genotypes, infector (susceptible cultivar to both pathotypes) was planted. All genotypes were inoculated with mixture of prevalent Pst races 78S84 (Yr 27 virulence) and 46S119 (Yr 9 virulence) at Karnal. Out of 58 released cultivars grown in different zones of the country, fifteen lines (HS 507, DBW 90, HD 3086, WH 1080, WH 1124, WH 1142, HD 4728, HI 8498, HI 8737, MPO 1215 (D), NIDW 295 (d), UAS 428 (D), UAS 446 (D), DBW 71, KRL 210) showed stripe rust ACI < 10.00 (average coefficient of infection). But among advance 88 wheat lines, there was good level of resistance in 50 lines (ACI <10.00). Lines having AUDPC values <20% of those of the susceptible checks (maximum AUDPC value 2500 on susceptible check) were considered to be slow rusters. In present study, some of the wheat varieties (DBW 93, HS 490, PBW 723, PBW 644, VL 829, VL 892, WH 1105, WR 544 ) grown at present in northern India were identified as slow ruster lines. The information generated can be utilized in improving the stripe rust resistance of popular cultivars.
Bangladesh Agricultural Research Institute
Paritosh Kumar,Malaker, Krishna Kanta, Roy, Md. Mostofa Ali, Reza, Naresh Chandra Deb, Barma, Md., Farhad, , , , , , , , , , , , , , , , , , , ,
Leaf rust is one of the major diseases of wheat in Bangladesh. The farmer fields and trial sites were regularly surveyed for rust assessment from 2010-2011 to 2016-2017 wheat growing seasons. Disease severity was recorded following BGRI protocols. Percentage of fields infected with leaf rust and the levels of disease severity varied with genotype, year, planting time and survey sites. Timely planted wheat either escaped or had less disease compared to late planted crop. Among our cultivated varieties, Shatabdi was either free from infection or exhibited only trace severity with resistant reaction. Variety Saurav, Bijoy, BARI Gom 27 , BARI Gom 28 , BARI Gom-29 and BARI Gom-30 were consistently free from leaf rust infection. BARI Gom 25 and BARI Gom 26 showed low to moderate disease levels with MRMS-MSS reactions, while the variety Prodip demonstrated moderate to high disease severity with susceptible response and it needs to be replaced by resistant variety to sustain wheat productivity.
La Trobe University
Reem Joukhadar, Sukhwinder Singh, Francis Ogbonnaya
Synthetic hexaploid wheat (SHW), generated by crossing Triticum turgidum (AABB) with Aegilops tauschii (DD), has been exploited in improving various traits in cultivated wheat. A number of recent studies decomposed the additive variance of different traits captured by multiple sets of variants (e.g. single nucleotide polymorphisms (SNPs) located on different chromosomes or genic/intergenic regions) in both human and animal quantitative genetics studies. In this research, we dissected the additive variance explained by the three subgenomes and seven homoeologous sets of chromosomes in SHW germplasm to gain a better understanding of trait evolution in newly synthesized wheat. Our SHW germplasm lines generated by crossing improved durum parents (AABB) with Aegilops tauschii (DD) parents were phenotyped for ten fungal/nematode resistance traits. The lines were genotyped by genotyping-by-sequencing and 6,176 SNPs were mapped with missing data of less than 20%. The D subgenome dominated the additive effects and this dominance affected the A more than the B subgenome. The D subgenome exhibited a 1.8-fold higher contribution than the A subgenome across all traits. This dominance was not inflated by population structure or by longer linkage disequilibrium blocks observed in the D subgenome. The cumulative effects of the three homoeologs in each set had a significant positive correlation with their cumulative explained additive variance. Moreover, an average of 70% for each chromosomal group cumulative additive variance came from one homoeolog that had the highest explained variance within the group across all ten traits. We hypothesize that structural and functional changes during diploidization may explain chromosomal group relationships as allopolyploids maintain a balanced dosage for many genes. Our results contribute to a better understanding of trait evolutionary mechanisms in SHW, and will facilitate effective utilization of wheat relatives in breeding.
Dryland Agricultural Research Institute, Sararood branch, AREEO, Kermanshah, Iran
Ehsan,Lorestani, Reza, Haghparast, Mohammad Reza, Jalal Kamali, Ahmed, Amri, , , , , , , , , , , , , , , , , , , , , ,
Yellow rust (Puccinia striiformis Westendorf f. sp. tritici) is an important disease on wheat worldwide and especially in the highlands of West and Central Asia. Wheat landraces are composed of complex, variable, genetically dynamic and diverse populations, in equilibrium with both biotic and abiotic stresses prevailing in their environment. A germplasm collection consisting of 380 durum wheat accessions conserved at National Plant Gene Bank (Seed and Plant Improvement Institute, Iran) with worldwide origins, along with four check varieties were screened for resistance to yellow rust, and were also evaluated for several drought adaptative traits under rainfed conditions during 2009-10 cropping season at Sararood agricultural research station, Kermanshah, Iran. The study was conducted to quantify the phenotypic diversity and exploring durum accessions for yellow rust resistance, and to characterize the agronomic profile of different subsets of accessions for reaction to local yellow rust races. High natural infection, caused by the predominant virulent races of 6E8A+ and Yr27+, was experienced as shown by the 100 S reaction of the check bread wheat ?Sardari? and several highly susceptible accessions. The tested accessions exhibited significant variation in yellow rust severity, ranging from highly resistant to highly susceptible. Approximately 12.1% of accessions were found to be resistant to yellow rust, 9.5% were moderately resistant, 10.5% were moderately susceptible and 67.9% were susceptible. The germplasm showed a relatively modest response to yellow rust as expressed by a decrease in 1000-kernel weight (TKW) and a lower yield of the susceptible vs. resistant subsets by 11.4% and 19.9%, respectively. A comparison of foreign vs. Iranian resistant accessions, revealed higher yield productivity, higher TKW, and shorter plant height for the foreign accessions. Durum germplasm may constitute valuable genetic material for breeding new durum varieties characterized by high yield productivity under rainfed conditions and with adequate resistance to yellow rust.
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.
Northwest A&F University
Yanping,Fu, kang, Wang, Yingbin, Hao, Zhensheng, Kang, , , , , , , , , , , , , , , , , , , , , ,
Wheat adult plant resistance (APR) to stripe rust, a non-race-specific and durable resistance, is ideal for breeding. However, the knowledge concerning APR mechanism is largely limited. In order to further investigate the molecular basics of APR to provide guidance for wheat breeding, we conducted the transcriptome sequencing of wheat XZ9104 infected by Puccinia striiformis f. sp. tritici (Pst) at seeding and adult stages, respectively. Comparative analysis revealed that many WRKY transcription factors (TFs) may participate in the APR to stripe rust, of which, TaWRKY79 transcript levels were sharply elevated at the early infection stage in seedling plants. To dissect the relationship between TaWRKY79 and APR, we further studied the function of TaWRKY79. Subcellular localization showed that TaWRKY79 is located in the nuclear, and TaWRKY79 protein contains a separated region for mediating transcriptional activation at the C-terminus (246-328 aa) by yeast one-hybrid analysis. When TaWRKY79 was silenced by virus-induced gene silencing (VIGS) in seedling plants, the Pst growth was attenuated, with shortened hyphae, reduced hyphal branches and colony size. Meanwhile, the expression of TaWRKY79 was highly suppressed by salicylic acid (SA) but induced by jasmonic acid (JA) in seedling of wheat, and the transcription levels of LOX2 and PDF2.2 were significantly reduced, but the expression of PR1.1 was enhanced in TaWRKY79 knocking-down seedlings of wheat. Hence, these findings suggested that TaWRKY79, as a SA/JA cross talk, might play a negative role in resistance defence response to Pst infection at seeding stage by simultaneously activating the JA-dependent pathway and suppressing the SA-dependent pathway.
Department of Plant Pathology, North Dakota State University, Fargo, ND
James,Kolmer, Maricelis, Acevedo, , , , , , , , , , , , , , , , , , , , , , , , , ,
Leaf rust, caused by Puccinia triticina Erikss. (Pt), is the most widespread wheat rust disease. Information on the virulence and genetic diversity of Pt is important for understanding the pathogen evolution, and thus effective management of wheat leaf rust. We used 20 Thatcher wheat near isogenic lines to study virulence diversity of 102 Pt isolates collected from tetraploid wheat, common wheat, and Triticale worldwide. Seven races were found among 57 isolates collected from tetraploid wheat while 21 races were observed among 40 common wheat type isolates. Four races were identified among the five isolates collected from Triticale. A subset of 30 Pt were genotyped using the Restriction-Associated DNA (RAD)-Genotype By Sequencing (GBS) adapted for the Ion Torrent sequencing platform. Phylogenetic analysis on 30 isolates using 2,125 SNP markers showed eight clusters supported by high bootstrap values. We observed higher genotypic diversity in common wheat type isolates compared to that in tetraploid wheat type isolates. Generally, there was a correlation between virulence phenotypes and SNP genotypes. Phylogeny results suggest that RAD-GBS is promising as a new technique for the study of population genetics in P. triticina.
Michel E. Ghanem, Sarrah Ben M'Barek, Gustavo Azzimonti, Silvia Pereyra, Silvia Germán, Felix Marza, Amor Yahyaoui, Pawan Singh, Michael Baum, Hans-Joachim Braun
Based on a global network of wheat partners, precision field-based wheat phenotyping platforms are being developed with the support of the CGIAR Research Program on Wheat and co-investing national agricultural research institutes. This collaboration strategy aims to i) strengthen the quality of phenotypic data to fully exploit the potential of genomic data, ii) strategic prioritization of activities based on trait screening capacities and regional needs, iii) sharing knowledge and germplasm to accelerate superior germplasm development and dissemination, iv) development of capacities. Phenotyping activities are being conducted for wheat blast (Magnaporthe oryzae) in Bolivia, Septoria tritici blotch (STB) in durum wheat in Tunisia, and for multiple diseases (leaf rust, Fusarium head blight, and STB) in bread wheats in Uruguay. Subject to further funding, additional platforms will be implemented, to contribute to a faster development of broad genetic based resistant, high yielding wheat varieties, and complementing evaluations currently performed for diseases and heat, drought and yield potential (Kenya, Ethiopia, Turkey, Mexico).
Crop Breeding Institute
Sripada Udupa, Charles Mutengwa, Peter Mavindidze
Host resistance is the most effective and economical method to minimize yield losses caused by rusts. The aim of this study was to detect the presence of resistance in 75 wheat genotypes. The presence of the genes viz. Sr2, Sr24, Lr34, Lr37, Lr46 and Lr68 was investigated using simple sequence repeat and sequence tagged site markers. Quantitative aspects of resistance to leaf rust were assessed through infection response (IR), disease severity (DS), coefficient of infection (CI), disease incidence (DI), leaf tip necrosis (Ltn) and area under disease progress curve (AUDPC) under natural epidemics. Highly significant (p <0.001) differences were observed among the genotypes for CI, DI, AUDPC and relative AUDPC (rAUDPC). Twenty genotypes exhibited high levels of adult plant resistance, recording CI less than 20% and AUDPC less than 300%, with moderately susceptible to susceptible reactions. The most frequently occurring gene was Lr46 (21%), followed by Lr68 (20%), Lr34 (19%) andLr37 (11%). The stem rust resistance gene Sr24 was absent in all the genotypes. Selection for Lr34 and Lr46 based on Ltn alone can sometimes be misleading because of its variable expression in different genetic backgrounds.