R Genes Research Articles

Stem rust in Western Siberia – race composition and effective resistance genes

Stem rust in recent years has acquired an epiphytotic character, causing significant economic damage for wheat production in some parts of Western Siberia. On the basis of a race composition study of the stem rust populations collected in 2016–2017 in Omsk region and Altai Krai, 13 pathotypes in Omsk population and 10 in Altai population were identified. The race differentiation of stem rust using a tester set of 20 North American Sr genes differentiator lines was carried out. The genes of stem rust pathotypes of the Omsk population are avirulent only to the resistance gene Sr31, Altai isolates are avirulent not only to Sr31, but also to Sr24, and Sr30. A low frequency of virulence (10–25 %) of the Omsk population pathotypes was found for Sr11, Sr24, Sr30, and for Altai population – Sr7b, Sr9b, Sr11, SrTmp, which are ineffective in Omsk region. Field evaluations of resistance to stem rust were made in 2016–2018 in Omsk region in the varieties and spring wheat lines from three different sources. The first set included 58 lines and spring bread wheat varieties with identified Sr genes – the so-called trap nursery (ISRTN – International Stem Rust Trap Nursery). The second set included spring wheat lines from the Arsenal collection, that were previously selected according to a complex of economically valuable traits, with genes for resistance to stem rust, including genes introgressed into the common wheat genome from wild cereal species. The third set included spring bread wheat varieties created in the Omsk State Agrarian University within the framework of a shuttle breeding program, with a synthetic wheat with the Ae. tauschii genome in their pedigrees. It was established that the resistance genes Sr31, Sr40, Sr2 complex are effective against stem rust in the conditions of Western Siberia. The following sources with effective Sr genes were selected: (Benno)/6*LMPG-6 DK42, Seri 82, Cham 10, Bacanora (Sr31), RL 6087 Dyck (Sr40), Amigo (Sr24, 1RS-Am), Siouxland (Sr24, Sr31), Roughrider (Sr6, Sr36), Sisson (Sr6, Sr31, Sr36), and Fleming (Sr6, Sr24, Sr36, 1RS-Am), Pavon 76 (Sr2 complex) from the ISRTN nursery; No. 1 BC1F2 (96 × 113) × 145 × 113 (Sr2, Sr36, Sr44), No. 14а F3 (96 × 113) × 145 (Sr36, Sr44), No. 19 BC2F3 (96 × 113) × 113 (Sr2, Sr36, Sr44), and No. 20 F3 (96 × 113) × 145 (Sr2, Sr36, Sr40, Sr44) from the Arsenal collection; and the Omsk State Agrarian University varieties Element 22 (Sr31, Sr35), Lutescens 27-12, Lutescens 87-12 (Sr23, Sr36), Lutescens 70-13, and Lutescens 87-13 (Sr23, Sr31, Sr36). These sources are recommended for inclusion in the breeding process for developing stem rust resistant varieties in the region.

Characterization of Virulence and Diversity of Puccinia graminis f. sp. tritici on Wheat in Egypt

Survey of wheat stem rust pathotypes and their identification using monogenic lines is significant in characterising virulence type variation, the geographical distribution of races. Variance in the population of the pathotypes is detected yearly utilising wheat stem samples collected from cultivated areas in Egypt. In our study, a sum of 104 and 40 wheat samples of stem rust were collected during growing seasons 2015/2016 and 2016/2017, respectively, from six locations, Beheira, Kafr-Elsheikh, Sharqiya, Minufiya, Bani Sweif, and Sohag. A sum of 70 and 53 races was isolated from samples collected in the previous years and identified in 2016/2017 and 2017/2018, respectively. The more frequent races involved TKTTC (18.25%) in 2015/2016 as well as PKSTC (6.25 %) in 2016/2017. For 2015/16, 26 pathotypes identified in Kafr-Elsheikh, which considered the most abundant population size (34.28 %), while for 2016/17, the Sharqiya governorate rated to be the most significant pathogen population size more than another population studied (49.05 %). Lines with Sr24, Sr38, and Sr31 genes were showed the highest gene efficacy against race groups, while the other genes displayed another reaction with the examined race groups

Status of Wheat Rust Research and Progress in Rust Management-Indian Context

The rusts of wheat, caused by three species of Puccinia, are very devastating diseases and are major biotic constraints in efforts to sustain wheat production worldwide. Their capacity to spread aerially over long distances, rapid production of infectious uredospores, and abilities to evolve new pathotypes, makes the management of wheat pathogens a very challenging task. The development and deployment of resistant wheat varieties has proven to be the most economic, effective and efficient means of managing rust diseases. Rust resistance used in wheat improvement has included sources from the primary gene pool as well as from species distantly related to wheat. The 1BL/1RS translocation from cereal rye was used widely in wheat breeding, and for some time provided resistance to the wheat leaf rust, stripe rust, and stem rust pathogens conferred by genes Lr26, Yr9, and Sr31, respectively. However, the emergence of virulence for all three genes, and stripe rust resistance gene Yr27, has posed major threats to the cultivation of wheat globally. To overcome this threat, efforts are going on worldwide to monitor rust diseases, identify rust pathotypes, and to evaluate wheat germplasm for rust resistance. Anticipatory breeding and the responsible deployment of rust resistant cultivars have proven to be effective strategies to manage wheat rusts. Efforts are still however being made to decipher the recurrence of wheat rusts, their epidemiologies, and new genomic approaches are being used to break the yield barriers and manage biotic stresses such as the rusts. Efficient monitoring of pathotypes of Puccinia species on wheat, identification of resistance sources, pre-emptive breeding, and strategic deployment of rust resistant wheat cultivars have been the key factors to effective management of wheat rusts in India. The success in containing wheat rusts in India can be gauged by the fact that we had no wheat rust epiphytotic for nearly last five decades. This publication provides a comprehensive overview of the wheat rust research conducted in India.

First Report of Race TTRTF of Wheat Stem Rust (Puccinia graminis f. sp. tritici) in Eritrea

HomePlant DiseaseVol. 104, No. 3First Report of Race TTRTF of Wheat Stem Rust (Puccinia graminis f. sp. tritici) in Eritrea PreviousNext DISEASE NOTES OPENOpen Access licenseFirst Report of Race TTRTF of Wheat Stem Rust (Puccinia graminis f. sp. tritici) in EritreaMehran Patpour, Annemarie F. Justesen, Asmelash W. Tecle, Mahboobeh Yazdani, Mohsen Yasaie, and Mogens S. HovmøllerMehran Patpour†Corresponding author: M. Patpour; E-mail Address: mehran.patpour@agro.au.dkhttp://orcid.org/0000-0002-4914-2697Global Rust Reference Center, Department of Agroecology, University of Aarhus, DenmarkSearch for more papers by this author, Annemarie F. JustesenGlobal Rust Reference Center, Department of Agroecology, University of Aarhus, DenmarkSearch for more papers by this author, Asmelash W. TecleMinistry of Agriculture, National Agricultural Research Institute, EritreaSearch for more papers by this author, Mahboobeh YazdaniFars Agriculture Organization, IranSearch for more papers by this author, Mohsen YasaieSeed and Plant Improvement Research Dep., Fars Agricultural and Natural Resources Research and Education Center, Shiraz, IranSearch for more papers by this author, and Mogens S. HovmøllerGlobal Rust Reference Center, Department of Agroecology, University of Aarhus, DenmarkSearch for more papers by this author AffiliationsAuthors and Affiliations Mehran Patpour1 † Annemarie F. Justesen1 Asmelash W. Tecle2 Mahboobeh Yazdani3 Mohsen Yasaie4 Mogens S. Hovmøller1 1Global Rust Reference Center, Department of Agroecology, University of Aarhus, Denmark 2Ministry of Agriculture, National Agricultural Research Institute, Eritrea 3Fars Agriculture Organization, Iran 4Seed and Plant Improvement Research Dep., Fars Agricultural and Natural Resources Research and Education Center, Shiraz, Iran Published Online:7 Jan 2020https://doi.org/10.1094/PDIS-10-19-2133-PDNAboutSectionsSupplemental ToolsAdd to favoritesDownload CitationsTrack Citations ShareShare onFacebookTwitterLinked InRedditEmailWechat Race TTRTF of Puccinia graminis f. sp. tritici was first detected in 2016 in a severe outbreak of wheat stem rust on thousands of hectares of durum and bread wheat in Sicily, Italy (Bhattacharya 2017; Patpour et al. 2018). However, a recent study suggested that TTRTF was already present in Georgia in 2014 (Olivera et al. 2019). During 2016 to 2018, 140 samples of rust-infected wheat and barley were collected from field trials and farmers’ fields in Eritrea and submitted to the Global Rust Reference Center (GRRC), Denmark. Fifty-one urediniospore isolates were derived from 62 samples recovered on the susceptible wheat cultivars Morocco and Line E. Race typing was completed for 40 isolates based on 20 North American wheat lines using the standard race-typing procedures and infection type (IT) criteria determining virulence and avirulence (Jin et al. 2008). All isolates except two, representing 24 sampling sites, were diagnosed as TTRTF, whereas two samples collected from farmers’ fields in Metera and Temajila were identified as TKKTF and TTKSK, respectively. In April 2019, two stem rust samples were collected from wheat in Fars province, Iran. After submission to GRRC, two single-pustule isolates per sample were raised and race typed as described above. All isolates were determined to be race TTRTF, previously reported without data documentation (Roohparvar and Omrani 2018). This is the first report of race TTRTF in Eritrea (2016) and southern Iran (2019). Six isolates of TTRTF from Eritrea and two from Iran were tested for additional virulence using 24 supplementary lines and cultivars containing Sr7a, Sr13a, Sr22, Sr25, Sr26, Sr27, Sr31, Sr32, Sr33, Sr35, Sr37, Sr39, Sr40, Sr44, Sr45, Sr47, SrSatu, Sr1RSAmigo, Sr50, Siouxland (Sr24+31), Sisson (Sr31+36), and Triumph 64 (SrTmp). Durum wheat Iumillo (Sr9g,12,+) and Leeds (Sr9e,13b,+) were also included in the experiment. The results were consistent for all isolates across two to three independent experiments. In summary, TTRTF had virulence for 23 Sr genes (IT 3 or higher): Sr5, Sr6, Sr7a, Sr7b, Sr8a, Sr9a, Sr9b, Sr9d, Sr9e, Sr9g, Sr10, Sr11, Sr13b, Sr17, Sr21, Sr35, Sr36, Sr37, Sr38, Sr44, Sr45, SrTmp, and SrMcN. Fed*3/Gabo*51BL.1RS-1-1 (Sr50) showed IT 3-3, which is significantly higher than for typical avirulent isolates. Simple sequence repeat genotyping of TTRTF isolates confirmed that they belonged to clade III-B defined by Olivera et al. (2019). The occurrence of TTRTF in Eritrea and Iran in 2016 and 2019, respectively, extends the known distribution of this race (sampling year in parenthesis): Italy (2016), Georgia (2014), Hungary (2017) (Olivera et al. 2019), and Egypt (2015 to 2016) (Esmail and Szabo 2018). TTRTF is considered a serious threat to wheat productivity in affected areas due to a broad virulence spectrum, including virulence to Sr13b from durum wheat and higher than usual IT for Sr50. Detection of TTRTF in different regions since 2014 stresses the high potential of onward spread to new areas and imminent risks for new epidemic outbreaks of wheat stem rust in many countries, because they are highly dependent on wheat as main source for food and feed. There is an urgent need to sustain wheat rust surveillance efforts globally and to identify effective sources of resistance to stem rust in cereal germplasm.The author(s) declare no conflict of interest.

Identification of Stem Rust Resistance Genes in the Winter Wheat Collection from Southern Russia.

The high yield potential of winter wheats cannot be realized due to disease pressure under field conditions. One of the most harmful of such diseases is stem rust, hence the constant search for sources of resistance and the development of new varieties resistant to stem rust is of great relevance. This study deals with the identification of stem rust resistance genes in a collection of winter wheats grown in Southern Russia. This genepool has not been studied yet. A total of 620 samples of winter soft wheat from various ecological and geographical zones were tested under field conditions. To identify the specific genes or alleles responsible for resistance, all samples were genotyped using PCR. As a result, the groups of resistant samples, carrying the Sr2, Sr31, Sr38 and Sr44 genes in various combinations, were identified. Most of the stem rust resistance was provided by the presence of the effective Sr44 gene. This information can be used in the future breeding work for stem rust resistance.

Identification of QTLs for resistance to leaf and stem rusts in bread wheat (Triticum aestivum L.) using a mapping population of ‘Pamyati Azieva × Paragon’

Leaf rust (LR) and stem rust (SR) are harmful fungal diseases of bread wheat (Triticum aestivum L.). The purpose of this study was to identify QTLs for resistance to LR and SR that are effective in two wheat-growing regions of Kazakhstan. To accomplish this task, a population of recombinant inbred lines (RILs) of ‘Pamyati Azieva × Paragon’ was grown in the northern and southeastern parts of Kazakhstan, phenotyped for LR/SR severities, and analyzed for key yield components. The study revealed a negative correlation between disease severity and plant productivity in both areas. The mapping population was genotyped using a 20,000 Illumina SNP array. A total of 4595 polymorphic SNP markers were further selected for linkage analysis after filtering based on missing data percentage and segregation distortion. Windows QTL Cartographer was applied to identify QTLs associated with LR and SR resistances in the RIL mapping population studied. Two QTLs for LR resistance and eight for SR resistance were found in the north, and the genetic positions of eight of them have matched the positions of the known Lr and Sr genes, while two QTLs for SR were novel. In the southeast, eight QTLs for LR and one for SR were identified in total. The study is an initial step of the genetic mapping of LR and SR resistance loci of bread wheat in Kazakhstan. Field trials in two areas of the country and the genotyping of the selected mapping population have allowed identification of key QTLs that will be effective in regional breeding projects for better bread wheat productivity.

Polymorphisms and Evolution of Solanum bulbocastanum Genes for Broad-Spectrum Resistance to Phytophthora infestans

For two decades, Solanum bulbocastanum Dun. has been challenging potato geneticists with its durable resistance to Phytophthora infestans Mont. de Bary, the causal agent of late blight, the most devastating potato disease. In this study, highly specific SCAR (sequence characterized amplified region) markers for three S. bulbocastanum genes of broad-spectrum resistance to P. infestans,RB/Rpi-blb1,Rpi-blb2 and Rpi-blb3, were employed to screen a vast collection of wild tuber-bearing species from several series of Solanum L. section Petota Dumort. and also potato hybrids and varieties. In S. bulbocastanum and S. stoloniferum Schlechtd. et Bche, the sequences of the markers Rpi-blb1-820 and Rpi-sto1-890, which recognize the LRR and CC regions respectively differed inconsiderably in the orthologous genes RB/Rpi-blb1 and Rpi-sto1. These two markers were tightly linked in diverse wild Solanum genotypes. These markers as well as RB-226, another marker recognizing the LRR region of the Rpi-blb1 gene, were obviously related to high resistance to P. infestans. One more marker recognizing the CC region of the gene, RB-629, was found in much wider range of Solanum genotypes; it was not related to resistance to P. infestans and is therefore considered non-specific. In addition to Rpi-blb1 = Rpi-sto1, the Rpi-blb2 and Rpi-blb3 genes were registered in both S. bulbocastanum and S. stoloniferum accessions. In most cases, three bulbocastanum genes were not linked together. The markers specific for Rpi-blb1 = Rpi-sto1 genes were found in the Solanum series Bulbocastana (Rydb.) Hawkes (genome designation BB) and Longipedicellata Buk. (genome designation AABB) and were absent from five Pinnatisecta Rydb. species also comprising genome B. The marker for Rpi-blb2 was found in the series Bulbocastana and Longipedicellata and also in three accessions of Pinnatisecta, while the Rpi-blb3 gene, the orthologue of widely spread R2 gene for resistance to P. infestans, was present in all three Solanum series. In contrast with Rpi-blb1 = Rpi-sto1, two other functional RB homologues, Rpi-bt1 in S. bulbocastanum and RBver in S. verrucosum Schlechtd. (genome AA), apparently diverged earlier in the evolution of tuber-bearing Solanum species. Our evidence on functional Rpi-blb1 = Rpi-sto1 genes in three Petota series substantiates the assumption that the B genome of tetraploid Longipedicellata evolved from diploid Bulbocastana rather than from diploid Pinnatisecta progenitors. Similar to wild Solanum species, the markers Rpi-blb1-820 and Rpi-sto1-890 were tightly linked in advanced potato hybrids and established varieties bred from S. stoloniferum as the conventional source of bulbocastanum genes for late blight resistance, but did not always match the markers for the Rpi-blb2 and Rpi-blb3 genes and the marker for the Rysto gene as an independent indicator of stoloniferum germplasm.

Validation and Marker-Assisted Selection of Stem Rust Resistance Gene Sr2 in Indian Wheat Using Gel-Based and Gel-Free Methods

Stem rust resistance gene Sr2 is an important slow-rusting gene which has provided resistance against stem rust for many years. The Sr2 gene has durable resistance against all stem rust pathogens including the Ug99 group of races. It shows recessive inheritance and is linked with two phenotypic markers, Pseudo Black Chaff (PBC) and High Temperature-Induced Seedling Chlorosis (HTISC). However, direct screening as well as phenotypic marker-based screening for selection of Sr2 is difficult due to the effect of environmental factors and genetic background. Microsatellite marker Xgwm533 linked to Sr2 gene is useful for rapid screening of large populations. Here we report validation and use of Xgwm533 for screening 21 wheat lines and 24 wheat genotypes for the presence of the Sr2 gene. Furthermore, we also report the presence of a new, smaller allele (97 bp) of Xgwm533 locus in a few genotypes that was also confirmed by sequencing. We also demonstrate a new SYBR green dye, melt-curve/profile-based assay for convenient screening of the Xgwm533 locus, where the presence of different alleles can be differentiated in a gel-free manner.

Genome-Wide Identification of Cassava Serine/Arginine-Rich Proteins: Insights into Alternative Splicing of Pre-mRNAs and Response to Abiotic Stress.

Serine/arginine-rich (SR) proteins have an essential role in the splicing of pre-messenger RNA (pre-mRNA) in eukaryote. Pre-mRNA with introns can be alternatively spliced to generate multiple transcripts, thereby increasing adaptation to the external stress conditions in planta. However, pre-mRNA of SR proteins can also be alternatively spliced in different plant tissues and in response to diverse stress treatments, indicating that SR proteins might be involved in regulating plant development and adaptation to environmental changes. We identified and named 18 SR proteins in cassava and systematically studied their splicing and transcriptional changes under tissue-specific and abiotic stress conditions. Fifteen out of 18 SR genes showed alternative splicing in the tissues. 45 transcripts were found from 18 SR genes under normal conditions, whereas 55 transcripts were identified, and 21 transcripts were alternate spliced in some SR genes under salt stress, suggesting that SR proteins might participate in the plant adaptation to salt stress. We then found that overexpression of MeSR34 in Arabidopsis enhanced the tolerance to salt stress through maintaining reactive oxygen species homeostasis and increasing the expression of calcineurin B-like proteins (CBL)-CBL-interacting protein kinases and osmotic stress-related genes. Therefore, our findings highlight the critical role of cassava SR proteins as regulators of RNA splicing and salt tolerance in planta.

Extreme resistance to late blight disease by transferring 3 R genes from wild relatives into African farmer-preferred potato varieties

Three late blight resistance (R) genes from wild potato species were transferred as a stack into the farmer-preferred varieties ‘Tigoni’ and ‘Shangi’. Transgenic events were tested by detached-leaf assays (DLA) and whole-plant assays (WPA) with isolates of Phytophthora infestans using 20,000 sporangia / mL inoculum. For the first DLA, 9 out of 13 ‘Tigoni’ and 10 out of 12 ‘Shangi’ transgenic events had scores below 3% of leaf affected area. 17 of the 19 transgenic events with low scores were subjected to a second DLA using two different P. infestans isolates. 8 of them exhibited extreme LB resistance while the remaining 9 transgenic events showed hypersensitive response (HR). 6 transgenic events (2 ‘Tigoni’ and 4 ‘Shangi’) with extreme resistance by DLA were subjected to WPA and they all exhibited extreme resistance to LB. Hence, this study demonstrates that a simple DLA predicts high level of resistance to late blight. R gene expression analysis in 18 transgenic events showed different transgenic events exhibiting different levels of expression in the three genes. However, that pathogen induction and / or high R gene expression are necessary for extreme resistance when transgenic events bear a stack of three R genes was not observed. Key words: Detached-leaf assay, late blight, Phytophthora infestans, resistance.

Characterization of mating type and the diversity of pathotypes of Phytophthora infestans isolates from Southern Brazil

Late blight is caused by the oomycete Phytophthora infestans, and it is the most devastating disease of potato in Southern Brazil. The objective of this work was to evaluate the variability of P. infestans isolates collected from potatoes in Rio Grande do Sul (RS), Parana (PR) and Santa Catarina (SC) states for their mating type (MT) and virulence. One hundred and twenty-eight isolates of P. infestans were collected between 2010 and 2012. They were characterized for mating type and subsequently evaluated for virulence/avirulence using a differential series of 11 potato clones. The virulence study was conducted in vitro by the leaf disc method, where the potato clones were inoculated with each isolate. Seventy-six isolates were identified as MTA2, 24 as MTA1, 17 as MTA1A2 and 11 as self-fertile. In addition, 79 pathotypes of P. infestans were detected in the survey and the largest number of races was identified in RS. The most frequent pathotypes identified were ‘14’ and ‘21’ and the vast majority of isolates overcame the R7 resistance gene, followed by the R3, R1 and R11 genes. Smaller numbers of virulent isolates were detected to the clones carrying the R5, R2 and R9 genes. Higher percentages of virulent and complex isolates were identified in the MTA2. High indices of diversity were observed in populations grouped by mating type and by state of collection. The highest value of the Gleason index HGR = (0.95) was obtained for the isolates from PR. Higher complex P. infestans populations were found in RS, and the least complex population was in PR.

Marker Assisted Transfer of Stripe Rust and Stem Rust Resistance Genes into Four Wheat Cultivars

Three rust diseases namely; stem rust caused by Puccinia graminis f. sp. tritici (Pgt), leaf rust caused by Puccinia triticina (Pt), and stripe rust caused by Puccinia striiformis f. sp. tritici (Pst), are the most common fungal diseases of wheat (Triticum aestivum L.) and cause significant yield losses worldwide including Australia. Recently characterized stripe rust resistance genes Yr51 and Yr57 are effective against pre- and post-2002 Pst pathotypes in Australia. Similarly, stem rust resistance genes Sr22, Sr26, and Sr50 are effective against the Pgt pathotype TTKSK (Ug99) and its derivatives in addition to commercially important Australian pathotypes. Effectiveness of these genes make them good candidates for combining with known pleiotropic adult plant resistance (PAPR) genes to achieve durable resistance against three rust pathogens. This study was planned to transfer rust resistance genes Yr51, Yr57, Sr22, Sr26, and Sr50 into two Australian (Gladius and Livingston) and two Indian (PBW550 and DBW17) wheat cultivars through marker assisted selection (MAS). These cultivars also carry other rust resistance genes: Gladius carries Lr37/Yr17/Sr38 and Sr24/Lr24; Livingston carries Lr34/Yr18/Sr57, Lr37/Yr17/Sr38, and Sr2; PBW550 and DBW17 carry Lr34/Yr18/Sr57 and Lr26/Yr9/Sr31. Donor sources of Yr51 (AUS91456), Yr57 (AUS91463), Sr22 (Sr22/3*K441), Sr26 (Sr26 WA1), and Sr50 (Dra-1/Chinese Spring ph1b/2/3* Gabo) were crossed with each of the recurrent parents to produce backcross progenies. Markers linked to Yr51 (sun104), Yr57 (gwm389 and BS00062676), Sr22 (cssu22), Sr26 (Sr26#43), and Sr50 (Sr50-5p-F3, R2) were used for their MAS and markers csLV34 (Lr34/Yr18/Sr57), VENTRIUP-LN2 (Lr37/Yr17/Sr38), Sr24#12 (Sr24/Lr24), and csSr2 (Sr2) were used to select genes present in recurrent parents. Progenies of selected individuals were grown and selected under field conditions for plant type and adult plant rust responses. Final selections were genotyped with the relevant markers. Backcross derivatives of these genes were distributed to breeding companies for use as resistance donors.

Chracteristic of perspective common spring wheat accessions for resistance to foliar diseases

Leaf and stem diseases (rusts and blotches) are harmful to spring wheat in all areas of its cultivation. The use of resistant varieties is an environmentally safe way of protection. The objective of the present study was to comprehensively evaluate leaf and stem disease resistance in 44 promising cultivars of soft spring wheat, as well as to identify Lr‑ and Sr‑genes in them. The accessions were obtained from the Kazakhstan‑Siberian Spring Wheat Improvement Network (KASIB) in 2017 and 2018. Wheat resistance to leaf and stem rust, to septoriosis and to tan spot was evaluated in field conditions in Southern Kazakhstan (infection plot at the Research Institute for Biological Safety Problems). Wheat seedlings resistance to septoriosis, leaf and stem rust was evaluated under laboratory conditions. The Lr and Sr genes were identified using a phytopathological test and molecular markers. Field studies resulted in selection of two lines, Lut. KS 14/09‑2 and SPCHS 69, with highly effective group resistance to rusts and blotches. By using molecular markers, the gene cluster Lr34/Sr57/Yr18/Pm38, Lr1 gene, and wheat‑rye translocation 1BL.1RS carrying genes Lr26/Sr31/Yr9/Pm8 were detected in Lut. KS 14/09‑2. A translocation from wheatgrass with highly effective genes of resistance to stem (Sr24) and leaf (Lr24) rusts, as well as 1AL.1RS translocation from rye with a complex of effective genes of resistance to fungous diseases and pests were detected in the line SPCHS 69. Eight wheat lines (Lut. 393/05, Lut. 2028, Lut. 261, Lut. 1103, Lut. 22‑17, Lut. 37‑17, line 4‑10‑16, Stepnaya 245) appeared to be resistant to Stagonospora nodorum blotch and tan spot; and four varieties (OmGAU‑100, Element 22, Stolypinskaya 2, and Silach) demonstrated resistance to leaf and stem rust. The molecular marker analysis showed moderate genetic diversity of the studied collection in terms of resistance genes. The genes Lr1, Lr9, Lr10, Lr19/Sr25, Lr24/Sr24, Lr26/Sr31/Yr9/Pm8, Lr34/Sr57/Yr18/Pm38, Lr37/Sr38/Yr17, both separately and in different combinations, were detected in the tested accessions. The evaluated material may be recommended for the use in wheat breeding for disease resistance in Russia and in Kazakhstan.

Polymorphisms in Promoter Region of the Interferon - Gamma Receptor1 Gene and its Relation with Susceptibility to Brucellosis

Background & Objective:Brucellosis is one of the most prevalent bacterial zoonotic diseases which afflicts both humans and animals. Genetic factors play an important role in susceptibility to brucellosis. One of these factors is interferon-gamma (IFN-), which is vital in the defense mechanism against infectious diseases such as brucellosis. The purpose of this study was to evaluate the relationship between two single nucleotide polymorphisms (SNPs) at positions -611 and -56 within the promoter region of interferon-gamma receptor-1 gene (IFN- R1) and brucellosis. Methods:In this research, the genomic DNA was collected from 60 peripheral blood samples infected with brucellosis and 68 healthy volunteers. DNA was extracted by salting out method. Then, DNA genotypes were analyzed using polymerase chain reaction-restriction fragment length polymorphisms (PCR-RFLP).Results:The results showed that there is a significant difference in -611 SNP frequencies between control and patient groups. At position -611, CC genotype was related to patient group (P=0.024) and TT genotype was related to the control group. According to the results, males had a higher frequency of Brucella infection.Conclusion:The presence of C allele in position -611 in IFNγ R1 gene promoter was related to a higher risk of disease and susceptibility to brucellosis. Moreover, the presence of T allele in position γ

Mapping of Novel Leaf Rust and Stem Rust Resistance Genes in the Portuguese Durum Wheat Landrace PI 192051

Leaf rust caused by Puccinia triticina Erikss. (Pt) and stem rust caused by Puccinia graminis f. sp. tritici Erikss. & E. Henn (Pgt) are serious constraints to production of durum wheat (Triticum turgidum L). The objective of this study was to identify leaf rust resistance (Lr) and stem rust resistance (Sr) genes/QTL in Portuguese durum landrace PI 192051. Four Pt-isolates, representing three virulence phenotypes (BBBQJ, BBBSJ & EEEEE) and six Pgt-races TTKSK, JRCQC, TKTTF, QFCFC, TPMKC and TMLKC were used to evaluate 180 recombinant inbred lines (RILs) derived from the cross Rusty (rust susceptible) × PI 192051-1 (rust resistant) at the seedling stage. The RILs were also phenotyped at the adult-plant stage in a stem rust nursery in Ethiopia in 2017. The RILs were genotyped using the Illumina iSelect 9K wheat SNP array. PI 192051-1 carries a previously unidentified major Sr gene designated as QSr.ace-7A on chromosome arm 7AS and Lr gene Lr.ace-4A in the pericentromeric region of chromosome 4A. In addition, three minor Sr QTL QSr.ace-1A, QSr.ace-2B and QSr.ace-4A were mapped in PI 192051-1 on chromosomes 1AL, 2BL, and 4A, respectively Lr.ace-4A could be co-located or tightly linked to QSr.ace-4A. Markers linked to the identified QTL/genes can be used for marker assisted selection. These findings enrich the genetic basis of rust resistance in both durum and common wheat.

Characterization of Ethiopian Wheat Germplasm for Resistance to Four Puccinia graminis f. sp. tritici Races Facilitated by Single-Race Nurseries.

In Ethiopia, breeding rust resistant wheat cultivars is a priority for wheat production. A stem rust epidemic during 2013 to 2014 on previously resistant cultivar Digalu highlighted the need to determine the effectiveness of wheat lines to multiple races of Puccinia graminis f. sp. tritici in Ethiopia. During 2014 and 2015, we evaluated a total of 97 bread wheat and 14 durum wheat genotypes against four P. graminis f. sp. tritici races at the seedling stage and in single-race field nurseries. Resistance genes were postulated using molecular marker assays. Bread wheat lines were resistant to race JRCQC, the race most virulent to durum wheat. Lines with stem rust resistance gene Sr24 possessed the most effective resistance to the four races. Only three lines with adult plant resistance possessed resistance effective to the four races comparable with cultivars with Sr24. Although responses of the wheat lines across races were positively correlated, wheat lines were identified that possessed adult plant resistance to race TTKSK but were relatively susceptible to race TKTTF. This study demonstrated the importance of testing wheat lines for response to multiple races of the stem rust pathogen to determine if lines possessed non-race-specific resistance.

Abstract SY45-02: Harnessing genetic interactions to advance whole-exome precision cancer treatment

Abstract Much of the current focus in cancer research is on studying cancer driver genes. In search for new and effective cancer drugs, this has been translated into searching for ‘actionable’ mutations in these genes, aiming at their therapeutic targeting. However, identifying novel genetic interactions occurring between cancer genes may open new drug treatment opportunities across the whole cancer genome. This talk will focus on studying the utility of two fundamental types of genetic interactions: The first are the well-known Synthetic Lethal interactions, describing the relationship between two genes whose combined inactivation is lethal to the cell. The second type are the much less studied Synthetic Rescues interactions, where a change in the activity of one gene is lethal to the cell but an alteration of its SR partner gene can rescue cell viability. I shall describe a new approach for the data-driven identification of these two types of genetic interactions by directly mining patients’ tumor data. Applying it to analyze the Cancer Genome Atlas (TCGA) data, we have identified the first pan-cancer genetic interaction networks shared across many types of cancer, which we then validated via existing and new experimental in vitro and in vivo screens. We find that: (a) Synthetic Lethal interactions offer an exciting venue for personalized selective anticancer treatments enabling the prediction of patients’ drug response and providing new selective drug target candidates, and (b) targeting Synthetic Rescue genes can mitigate resistance emerging to primary cancer therapy, including both targeted and immunotherapy. (c) Finally, I shall present recent unpublished results showing that we can quite accurately predict the context specificity of emerging synthetic-lethal based combination therapies, both in terms of the cancer types that are sensitive to them and re. the specific sensitivity of individual patients within a cancer type. Importantly, these results are obtained without the need for specific training on the datasets predicted and are derived directly from patients data, thus increasing the likelihood of their translational relevance. Citation Format: Eytan Ruppin. Harnessing genetic interactions to advance whole-exome precision cancer treatment [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr SY45-02.

Comparative transcriptome analysis reveals defense responses against soft rot in Chinese cabbage

Pectobacterium carotovorum ssp. carotovorum (Pcc) is a necrotrophic bacterial species that causes soft rot disease in Chinese cabbage. In this study, plants harboring the resistant mutant sr gene, which confers resistance against Pcc, were screened from an 800 M2 population mutated by ethyl methane sulfonate (EMS) and scored in vitro and in vivo for lesion size. The transcript profiles showed ~512 differentially expressed genes (DEGs) between sr and WT plants occurring between 6 and 12 h postinoculation (hpi), which corresponded to the important defense regulation period (resistance) to Pcc in Chinese cabbage. The downstream defense genes (CPK, CML, RBOH MPK3, and MPK4) of pathogen pattern-triggered immunity (PTI) were strongly activated during infection at 12 hpi in resistant mutant sr; PTI appears to be central to plant defense against Pcc via recognition by three putative pattern recognition receptors (PRRs; BrLYM1-BrCERK1, BrBKK1/SERK4-PEPR1, BrWAKs). Pcc triggered the upregulation of the jasmonic acid (JA) and ethylene (ET) biosynthesis genes in mutant sr, but auxins and other hormones may have affected some negative signals. Endogenous hormones (auxins, JAs, and SA), as well as exogenous auxins (MEJA and BTH), were also verified as functioning in the immune system. Concurrently, the expression of glucosinolate and lignin biosynthesis genes was increased at 12 hpi in resistant mutant sr, and the accumulation of glucosinolate and lignin also indicated that these genes have a functional defensive role against Pcc. Our study provides valuable information and elucidates the resistance mechanism of Chinese cabbage against Pcc infection.

Molecular identification of the stem rust resistance genes in the introgression lines of spring bread wheat

A total of 57 introgression lines and 11 cultivars of spring bread wheat developed by All-Russian Institute of Plant Protection and cultivated in the Volga Region were analyzed. The lines were obtained with the participation of CIMMYT synthetics, durum wheat cultivars, direct crossing with Agropyron elongatum (CI-7-57) and have introgressions from related species of bread wheat, namely translocations from Ag. elongatum (7DS-7DL-7Ae#1L), Aegilops speltoides (2D-2S), Ae. ventricosum (2AL-2AS-2MV#1), Secale cereale (1BL-1R#1S), 6Agi (6D) substitution from Ag. intermedium and triticale Satu. Cultivars and lines were assessed for resistance to Saratov, Lysogorsk, Derbent and Omsk stem rust pathogen populations (Puccinia graminis f. sp. tritici), and analyzed for the presence of the known Sr resistance genes using molecular markers. The analysis of the cultivars’ and lines’ resistance to the Saratov pathogen population in the field, as well as to Omsk, Derbent and Lysogorsk populations at the seedling stage, showed the loss of efficiency of the Sr25 and Sr6Agi genes. The Sr31 gene remained effective. Thirty one wheat lines out of 57 (54.4 % of samples) were resistant to all pathogen populations taken into analysis. The Sr31/Lr26, Sr25/Lr19, Sr28, Sr57/Lr34 and Sr38/Lr37 genes were identified in the introgression lines. The Sr31/Lr26 gene was identified in 19 lines (33.3 % of samples). All lines carrying the 1RS.1BL translocation (Sr31/Lr26) were resistant to all pathogen populations taken into analysis. The Sr25/Lr19 gene was identified in 49 lines (86 %). The gene combination Sr31/Lr26+ Sr25/Lr19 was identified in 15 lines (26.3 %). The gene combinations Sr38/Lr37+Sr25/Lr19, Sr57/Lr34+Sr25/Lr19 and Sr31/Lr26+Sr25/Lr19+Sr28 were identified in 3 introgression lines. These three lines were characterized by resistance to the pathogen populations studied in this work. The Sr2, Sr24, Sr26, Sr32, Sr36 and Sr39 genes were not detected in the analyzed wheat lines.

Characterization of stem, stripe and leaf rust resistance in Tajik bread wheat accessions

Stem rust [causal organism: Puccinia graminis f. sp. tritici (Pgt)], stripe rust [Puccinia striiformis f. sp. tritici (Pst)], and leaf rust [Puccinia triticina (Pt)] are important fungal diseases of wheat in Central Asia and worldwide. Therefore, identification of seedling and adult plant resistance (APR) genes is of major importance for the national wheat breeding program in many countries. The objectives of this study were to identify genes that confer seedling and APR resistances in widely grown wheat cultivars, landraces and advanced lines from Tajikistan. A total of 41 wheat accessions were inoculated with eleven races of Pgt, twelve races of Pst and nine races of Pt for postulation of Sr (stem rust), Yr (yellow or stripe rust), and Lr Lr (leaf rust) resistance genes at the seedling stage. In addition, all of the accessions were tested in field trials for the response to stem rust and stripe rust. Genes for seedling stem rust resistance (i.e. Sr5, Sr6, Sr11, Sr31, and Sr38), stripe rust resistance (Yr9, Yr17, and Y27), and leaf rust resistance (Lr16 and Lr26) were postulated in the Tajik wheat. The presence of the pleiotropic APR genes Sr2/Yr30/Lr27 (associated with pseudo-black chaff phenotype) and Lr34/Yr18/Sr57 (associated with leaf tip necrosis phenotype), and also Lr37 were assessed in the field and confirmed with linked molecular markers. In most of the wheat accessions, resistance genes could not be postulated because their infection types did not match the avirulence or virulence profile of the Pgt, Pst and Pt races tested. Six, seven, and nine accessions were identified that likely possess new genes for resistance to stem rust, stripe rust, and leaf rust, respectively, which have not been described previously. The research demonstrates the presence of effective seedling resistance and APR genes in widely grown wheat accessions that could facilitate further rust resistance breeding in the national wheat breeding program in Tajikistan.