Department of BioEngineering, Birla Institute of Technology, Mesra, Ranchi, India
Manish Kumar, Kunal Mukhopadhyay
Bread wheat (Triticum aestivum L.) being the world's most popular edible cereal, plays a major role in global economy. Rust in wheat leaves, caused by Puccinia triticina, affects grain quality and severely retards its production worldwide. Micro(mi)RNAs are considered major components of gene silencing and so have a great role to play during stress. The present study focuses on identification of miRNAs, produced by host to suppress pathogen as well as delivered by pathogens to encounter host defence mechanism. Therefore, these miRNAs may be called as leaf rust responsive microRNAs. Small RNA and degradome libraries were prepared from a pair of near isogenic lines of wheat (HD2329, HD2329+Lr24), one set was mock inoculated while the other set was inoculated with urediniospores of leaf rust pathogen. Using these libraries as input a vast number of miRNAs rather a population of miRNAs were identified derived from wheat that were targeting genes mostly involved in functions like defense response, signal transduction, development, metabolism, and transcriptional regulation.
When reads specifically produced under pathogen inoculation were taken as input with Puccinia triticina genome sequences as reference, only three putative miRNA precursor loci were detected and the molecules produced were called miRNA-like molecules as their precursors lacked one or two criteria essential for a true miRNA precursor. The identified miRNAs were targeting genes like F-box protein, MAP kinase, calmodulin and susceptible antioxidant protein. We further identified the presence of argonaute and dicer like domains in Puccinia proteome available at FungiEnsembl which strengthens presence of RNAi-like activities in Puccinia.
In addition, differential expression of wheat as well as Puccinia small RNAs using stem loop RT-PCR under varying time points of disease progression (0-168 hpi) revealed their direct connection with stress responses.
The University of Jordan
Ayed Al Abdallat, Monther Tahat
Studies on whet stem rust (WSR) in Jordan are considered to be old. There was only one study conducted in the late 1980's by Abu-Blan and Duwayri (1989) to evaluate the infection of wheat cultivars with black stem rust disease (Puccinia graminis f. sp. tritici). Recently, reports of stem rust were published in Israel and Lebanon in 2010 and first report of Ug99 was reported in Egypt in 2014. The objectives of our research are to: (i) survey wheat growing areas for WSR in Jordan during the years 2017-2020, (ii) identification of WSR races isolated from Jordan morphologically and molecularly, (iii) analyze rust populations in terms of their response to known differential sets, pathotype distribution and diversity, (iv) screening the response of Jordanian wheat germplasm to the identified WSR strains, and (vi) study the population diversity of WSR races using RT-PCR and SNP genotyping. In 2017 a total of 270 fields of wheat and barley in the wheat and barley growing areas in Jordan were surveyed from March-May. The survey covered northern, middle, and southern parts of Jordan (arid and semi-arid regions). Altitude, longitude, and latitude data was recorded. Only few WSR pustules (n=4) were collected because the environmental conditions were not suitable for the disease to develop. On the other hand, wheat stripe rust was very common in the wheat growing areas mainly at the southern parts of the country. Other fungal plant pathogens were also reported including smuts, spots, blotches, powdery mildew, crown rot, fusarium head blight, and flag smut.
Institute of Crop Science and Resource Conservation, Rheinische Friedrich-Wilhelms-University of Bonn
Mohammad Wali,Salari, Kobra, Yusefi, Mohammad, Yusefi, Gul Mohammad, Ajir, Wakil Ahmad, Sarhadi, Jens, L?on, , , , , , , , , , , , , , , , , ,
Bread wheat is a staple food in Afghanistan. Breeding for improving yield and its components in Afghan bread wheat without using new molecular methods such as marker-assisted selection (MAS) and quantitative trait loci (QTL) mapping approaches is difficult. Therefore study of genetic analysis by focus on yield and its components as first steps is necessary. Genetic analyses were performed on a winter wheat core collection of 20 accessions and commercial varieties sampled from different regions of Afghanistan and twenty agronomic traits were evaluated over three years under fully irrigated, rain-fed and drought treatments. Grain yield was the most important trait to water deficit and was highly correlated with other agronomic traits. The germplasm was structured into two sub-populations. Field plots of the genotypes were treated to one of three treatments including full irrigation, rain supplied and rain-sheltered. A randomized complete block design with three replicate was used every year of the trial. For every agronomic trait, variance components, heritability (h2) and genetic correlations was calculated. Results of the study showed that these genotypes may be good source for national breeding programs. The multiple statistical in this study showed that results of genetics correlation and regression analysis are same. Further analysis of these traits with additional experimental data to attain persuasive conclusion is suggested.
State Key Laboratory of Crop Stress Biology for Arid Areas, Northwest A&F University, Yangling, Shaanxi, P. R. China
Qilin,Wang, Jianhui, Wu, Qingdong, Zeng, Lili, Huang, Dejun, Han, Zhensheng, Kang, , , , , , , , , , , , , , , , , ,
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.
ICAR NRC Plant Biotechnology
The present challenge in wheat breeding is to decipher the molecular mechanisms of heat stress response and thermotolerance in detail for future applications. Several reports indicate the ability of plants to maintain a memory of stress exposure throughout their ontogenesis and even transmit it faithfully to the following generation. Here, three diverse genotypes of wheat viz., HD2967, WR544 and C306 were used for thermotolerance assays. The genotype HD2967 was able to withstand heat stress regimes (37?C and 42?C, 2 hours). Harvested seeds were sown and further raised for two consecutive years and phonotypical data evaluated in natural field condition by exposing to heat stress during generative stages in a heat trap chamber. Maximum tiller numbers and flag leaf length were noticed in second generation plant of 37?C heat exposure whereas flag leaf width in second generation 42?C heat exposure relative to the untreated plant. Auricle length showed no difference but plant height was notably increased in the second year in all the heat exposed plants. In grain yield index, ear head length was greater in the second year and fluctuations in grain number was noticed among the heat treated plant with more yields in 42?C and 42?C HTHT in the second year. IRGA and SPAD recording showed high photosynthesis and chlorophyll content in 37?C HTHT. High modulation of transcripts of several genes involved in DNA methylation and heat stress were also observed. The domino effect of heat stress in earlier generation, in this transgenerational analysis, points towards a probable epigenetic effect. Further studies are in progress to confirm and clarify the mechanisms for future manipulation in breeding for thermotolerance.
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.
Department of Botany, Faculty of Biology, Government College Murree, Pakistan
Barkat Ali, Muhammad Fayyaz, Atiq ur Reman Rattu, Abdul Samad Mumtaz, Muhammad Imtiaz
The new arrival of wheat rust pathotypes through migration during wheat cropping season requires regular monitoring to secure wheat production. In the present study, we collected leaf rust (Puccinia triticina Eriks.) infected wheat leaves from three major wheat growing provinces of Pakistan in the year 2014 to assess the haplotype diversity of P. triticina (Pt) isolates. The rDNA ITS sequence data of collected isolates was used in NCBI BLAST analysis. The blast hits showed best matches with Pt accessions EU014050 (Iran), JN120331 (Iran), JX533577 (Iran), AY956549 (Iran), DQ417412 (Czech Republic), DQ417418 (Israel), DQ417413 (Slovakia) and AF511083 (Louisiana). However, in cluster analysis, the Pakistani isolates showed strong bootstrap support with only Iranian and Indian (races 77-5 & 104-4) accessions that indicated eastward migratory mode of Pt pathotypes in Pakistan through westerly wind patterns. The predominant genotype DQ417412 (similar in alignment with AY956549 from Iran) overcome the resistance of top Pakistan mega varieties Seher06, Inqilab91, Kiran95, SKD1, TJ83 and NIFA-Batoor. Hence, the ITS based information remains a rapid molecular tool for pathogen surveillance across countries and continents.
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.
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.