A wheat genotype PBW343+Gpc-B1+LR24 containing the high grain protein content (GPC) gene Gpc-B1 linked to marker Xucw108 was used as the donor parent to transfer Gpc-B1 and Lr24 into Eastern Gangetic Plains (EGP) cv. HUW234 and HUW468 that were released in 1986 and 1999, respectively. The backcrossing program involved the following steps: (i) foreground selection, (ii) marker selection, and (iii) recovery of recipient parent genome. Grain protein contents were recorded for all selected plants from the BC2F2:3 generation. The dominant marker Xucw108 was used for foreground selection, and heterozygous plants were identified through progeny testing. For RPG recovery, both genotypic and phenotypic selection was used. Introgression of the high GPC gene into the recipient background without yield loss was completed in 5 years, starting from 2009-10 (F1) and completed in 2013-14 (BC2F5). A conventional selection program would take the same time to reach BC2F5 but ensuring the transfer of GPC would not not be possible. Ten selected single plants from the BC2F3:4 generation had comparable yields of the parents with 26% higher GPC than the recurrent parent HUW 234. Eight selected plants had comparable yields and 34% higher GPC than HUW 468. Multi-row progenies (BC2F4 and BC2F5) of each selected plant were evaluated in yield traits with the donor and recipient parents as controls during 2012-13 and 2013-14. Two lines based on each recurrent parent were identified with significantly higher GPC with no yield penalty. The study reinforced the belief that MAS in combination with phenotypic selection could be a useful strategy to develop high GPC genotypes without sacrificing grain yield. These lines will be submitted to national trial where MAS derived lines require only two years of testing compared to four years for conventionally bred lines.
Primary Author: Mishra, Department of Genetics and Plant Breeding, Institute of Agricultural Sciences, Banaras Hindu University, India
The Global Rust Reference Centre (GRRC, www.wheatrust.org) was established in 2008 upon the request of CIMMYT and (ICARDA) and extended in 2011 by the support of the Borlaug Global Rust Initiative. GRRC serve as a global hub for investigating wheat rust fungi and can receive alive samples from all countries year round. The activities of GRRC comprise pathotyping of wheat yellow rust and wheat stem rust, as well as training of students and scientists, data handling and storage (databases) and reporting. The current research activities have a focus on evolutionary population biology, as well as basic genetic and genomic studies in yellow rust. The “Wheat Rust Toolbox” and the team behind has become part of the GRRC and all data generated by GRRC will be stored in this system. Data management, research activities and dissemination will be coordinated and integrated with partner information platforms at CIMMYT, ICARDA, Cornell University and other global partners. The quarantine greenhouse space has in recent years been enlarged by more than 50% allowing GRRC to take in more rust samples and students. The GRRC activities expanded significantly in 2011 and 2013 via grants from the Danish Strategic Research Council and the Ministry of Food, Agriculture and Fisheries. One of these initiatives, RUSTFIGHT, has a focus on understanding “aggressiveness” and involves a number of Danish and international partners, including ICARDA and CIMMYT, INRA and the John Innes Centre (UK), and private Danish plant breeding Industry.
Primary Author: Mogens Hovmoller, Aarhus University, Denmark
Stem rust, caused by Puccinia graminis f. sp. tritici (Pgt), is one of the most serious disease of wheat worldwide. The discovery of new Pgt races in Africa, Ug99 and its variants, brings a new threat to global wheat production. In this study, 50 single pustule stem rust samples, were collected during 2015-2016 from the International Stem rust Trap Nursery (ISRTN) and commercial wheat fields in Sakha, the most important wheat growing region in Egypt. SNP-genotyping was carried out at USDA-ARS Cereal Disease Laboratory. Infection and genotype data confirmed that none of these samples belonged to the Pgt Ug99 race group. Forty-five samples were successfully genotyped consisting of 12 multi-locus genotypes (MLGs). The majority (86.7%) of the samples belonged to three clades: 10 samples, clade III-B (MLG.04, race TTRTF) collected from Misr 3, Sakha 95 and Sids 14 wheat lines; 12 samples, clade IV-A.2 (MLG.06, race TKTTF) collected from Sr 5, Sr6, Sr7a, Sr7b, Sr8b, Sr9a, Sr9e, Sr10, Sr11, Sr15, Sr16 and Sr17 wheat lines; 17 samples, clade IV-E.2 (MLG.11, race TKKTF) from Sr13, Sr14, Sr19, SrMcN, Sr24, Misr 1, Misr 2, Sakha95 and Sids 12 wheat lines. Pgt samples belonging to clades IV-A.2 and IV-E.2 have been observed from Europe to the Middle East, and samples from clade III-B from the southern Caucasus Mountains, Middle East to northeast Africa. The remaining six samples collected from Sr12, Sr18, Sr20, Sr21, Sr22 and Sr25 wheat lines represent two new genotypes (MLG.14 and MLG.17) that have not been assigned to clades. MLG.14 was also observed in samples from Azerbaijan, Iraq and Eritrea. In contrast, this represents the first detection of MLG.17. These results suggest continued variability of the Pgt population in Egypt therefore, emphasizing the importance regularly monitoring to timely identify new races, and utilize this information in screening and identification of effective sources of resistance.
Primary Author: Mohamed Esmail, Wheat Dis. Res. Dept., Plant Pathol. Res. Inst., A.R.C., Sakha, Egypt
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.
Primary Author: Mohammadi, Dryland Agricultural Research Institute, Sararood branch, AREEO, Kermanshah, Iran
Stem rust is a potentially destructive fungal disease of wheat worldwide. In 1998 Pgt pathotype TTKSK virulent to Sr31 was detected in Uganda. The same pathotype was confirmed in Lorestan and Hamedan provinces of Iran in 2007. We used a derivative of race TTKSK to phenotype 62 Iranian wheat landraces (resistant to stripe rust in a previous study) at the seedling stage to this new pathotype (TTSSK). Twenty eight accessions were evaluated for the presence of resistance genes Sr2, Sr22, Sr24, Sr25, Sr26, Sr35, Sr36 and Srweb using SSR markers. None carried Sr2, Sr24 or Sr26, but the presence of Sr22, Sr25, Sr35 and Sr36 was indicated. Some susceptible landraces predicted to carry Sr2 by marker analysis require further investigation. To evaluate defense gene expression in compatible and incompatible stem rust interactions we sampled resistant and susceptible cultivars at 0, 12, 18, 24, 72 hours post-inoculation (hpi). ?-1,3 glucanase expression was studied using qGLU-S and qGLUU-AS primers and a real-time PCR step-one ABI machine, with ?-tubulin and EF1-? genes used as internal controls. In incompatible interactions defense gene expression was increased at 24 hpi, but in compatible interactions the highest level of expression occurred at 12 hpi and was significantly decreased at 18 hpi. The results revealed that expression of defense genes such as ?-1,3 glucanase was earlier in compatible than in incompatible interactions but the expression level was less in incompatible interactions. On the other hand, in susceptible genotypes the expression of defense genes increased immediately after inoculation and declined sharply after infection. In contrast defense gene expression in resistant genotypes began to increase after establishment of the pathogen.
Primary Author: Mojerlou , Tarbiat Modares University of Tehran, Iran
The combination of several additive, partial resistance genes has been proposed as a preferred strategy to breed wheat cultivars with acceptable levels of durable resistance. The German winter wheat cv. Centrum has displayed high levels of adult plant stripe rust resistance (APR) in field environments for many years. One hundred and fifty one F2:7 RILs were developed from a cross between susceptible landrace Mingxian169 and Centrum to determine the inheritance of the APR resistance. The RILs and parents were evaluated for maximum disease severity (MDS) in the field during the 2015-2016 and 2016-2017 cropping seasons. Affymetrix 35K single nucleotide polymorphism (SNP) arrays were used to genotype the RILs and parents. In addition, the 660K SNP array was used to genotype bulked extreme pools and parents for saturation mapping. Four stable QTL were detected in all tested environments using inclusive composite interval mapping (ICIM); namely QYrCEN.nwafu-4AL, QYrCEN.nwafu-4BS, QYrCEN.nwafu-7BL, and QYrCEN.nwafu-7DS. QYrCEN.nwafu-4BS and QYrCEN.nwafu-7DS were contributed by MX169, QYrCEN.nwafu-4AL and QYr-CEN.nwafu-7BL were contributed by Centrum. QYrCEN.nwafu-7BL and QYrCEN.nwafu-4AL appear to represent new APR loci based on map comparisons. QYrCEN.nwafu-4BS contributed by MX169 also seems to represent a new locus. QYrCEN.nwafu-7DS is likely Yr18. Although MX169 was fully susceptible in our nurseries it is positive for the widely used marker csLV34. Reference lines carrying Yr18 are moderately resistant. Our hypothesis is that MX169 probably carries the inhibitor reported in Chinese landrace varieties by Wu et al. (2015, Plant Breeding 134: 634-640). SNP markers within these QTL were converted to KASP markers and validated in a subset of 120 diverse lines. These KASP markers should be useful for marker-assisted selection to improve stripe rust resistance in breeding programs.
Primary Author: Mu, State Key Laboratory of Crop Stress Biology for Arid Areas, Northwest A&F University, Yangling, Shaanxi, P. R. China
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)).
Primary Author: Muminjanov, Food and Agriculture Organization of the UN
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.
Primary Author: Mustarin, Bangladesh Agricultural Research Institute
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.
Primary Author: Mutari, Crop Breeding Institute
The wild relatives of wheat, the genus Aegilops is of great interest for breeding. Many species of the genus Aegilops are distinguished by such valuable properties as resistance to rust diseases, drought resistance, and salt tolerance.
The evaluation of local wheat varieties on resistance to yellow rust showed that local varieties showed high resistance to the pathogen and were amazed from 0 to 10 %. Evaluation of Aegilops species for resistance to yellow and brown rust, showed that the species Aegilops triunciales showed high resistance to yellow and brown rust, except Ae. triunciales, collected in the Rudaki district and showed moderate resistance to brown rust - 20%. The view of the Aegilops cylindrical collected in the Rudakinsky district showed a moderate resistance to yellow rust and a high resistance to brown rust. View Aegilops tauschii, collected in the Rudakinsky district had a high resistance to yellow and brown rust. Species Aegilops crassa to yellow and brown rust showed a reaction from moderate resistance - 30% to moderate susceptibility - 40%. As a result of the studies to assess the resistance of wheat varieties in Central Tajikistan, the cultivars Jaldak, Safedaki Gorchivin and Viyod, which had high resistance to yellow and brown rust, as well as Pamir and Surkhak varieties, showed moderate resistance.
Distinct varieties of wheat with high and moderate resistance to the pathogen of yellow rust can be used as parental forms for breeding new varieties of wheat. Studies on assessing the resistance of Aegilops species have shown that the species Aegilops triunciales has a high resistance to the pathogen of yellow rust. Species of Aegilops tauschii and Aegilops crassa, collected from the Hissar salt source, had moderate resistance to the pathogen. These species of Aegilops can be used in the selection of new varieties of wheat.
Primary Author: Nasyrova, IBPPG TAS