The University of Agriculture, Peshawar, Pakistan
Muhammad,Khan, Sangay, Tshewang, Sarala, Lohani, David, Hodson, Muhammad, Imtiaz, Sajid, Ali, , , , , , , , , , , , , , , , , ,
The Himalayan region of Pakistan and China has been shown to be the centre of diversity of Puccinia striiformis, however, little is known about the Eastern part of the Himalayas. We studied the genetic structure of P. striiformis from Nepal and Bhutan in comparison with Pakistan through microsatellite genotyping of 66 isolates from Nepal (35 isolates) and Bhutan (31 isolates) collected during 2015 and 2016. Genetic analyses revealed a recombinant and highly diverse population structure in Bhutan and Nepal. A high level of genotypic diversity was observed for both Bhutan (0.92) and Nepal (0.67) with the detection of 53 distinct multilocus genotypes (MLGs) in the overall population; 28 for Bhutan and 27 for Nepal. Mean number of alleles per locus was higher in Bhutan (3.33) than Nepal (3.11), while the gene diversity was higher in Nepal (0.4279) than Bhutan (0.3552). A non-significant difference between the observed and the expected heterozygosity in both populations further confirmed the recombinant structure. Analyses of population subdivision revealed a low divergence between Nepal and Bhutan (FST=0.1009), along with the detection of certain common MLGs in both populations. The overall population was clearly divided into six genetic groups, with no geographical structure, confirmed by the distribution of multilocus genotypes over two countries, suggesting a potential role of migration. Comparison with the Pakistani P. striiformis population suggested a high genotypic diversity in Nepal (0.933) and Bhutan (0.959), though lower than the previously reported from Himalayan region of Pakistan (Mansehra; 0.997). The overall high diversity and recombination signature suggested the potential role of recombination in the eastern Himalayan region (Nepal and Bhutan), which needs to be considered during host resistance deployment and in the context of aerial dispersal of the pathogen.
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).
Sher-e-kashmir University of Agricultural Sciences and Technology of Kashmir, Jammu and kashmir, India
Reyazul Rouf Mir, Shazia Mukhtar, Rahul R., Nelwadker, M., Ashraf Bhat
In India stripe rust of wheat (Triticum aestivum L.) is important as it occurs in the severe form in North Hill Zone (NHZ) covering states of Jammu and Kashmir, Himachal Pradesh and Uttarakhand. Stripe rust thrives well under cool and moist field conditions and sometimes its epidemic is so severe that it destroys the whole crop. Although the fungicides have been applied to control this disease but their use is unfriendly to the environment and they add to the input cost of farmers. The breeding for disease resistance is an effective strategy and involves identification of stable sources of resistance and their utilization. Deployment of yellow resistance genes has helped in suppressing the intensity, effectiveness and frequency of rust epiphytotics. Many sources of yellow rust resistance exist, but these are either incompletely characterized or these have not been studied in sufficient detail needed for their designation. The present study was conducted to screen for yellow rust resistance a set of 300 wheat germplasm lines received from various national and international germplasm centers viz., CIMMYT, Mexico; CIMMYT, Ankara, Turkey; IARI sub-station, Wellington, Tamil Nadu; IIWBR, Karnal; IIWBR, Flowerdale, Shimla and SKUAST-Kashmir, Srinagar for yellow rust resistance (46S119 and 78S84 as most prevalent races) over years 2012 to 2016 under field and ployhouse conditions. The study could identify eleven wheat lines showing varying levels of resistance to yellow rust races 46S119 and 78S84 when scored at adult plant stage under both conditions. The area under disease progress curve (AUDPC) scores of the lines identified as resistant was lowest as compared to yellow rust susceptible check (Agra Local). The resistant lines identified in the study could efficiently be utilized in yellow rust breeding programmes of the country and thereby deployment of such genes over space and time for an effective and long lasting control.
School of Agricultural Biotechnology, Punjab Agricultural University, Ludhiana-141004 India
Rohtas,Singh, Satinder, Kaur, Parveen, Chhuneja, , , , , , , , , , , , , , , , , , , , , , , ,
Leaf rust caused by Puccinia triticina is one of the most historical and economically important wheat diseases. Breeding for new cultivars with effective gene combinations is the most promising approach for reducing losses due to leaf rust. Wild emmer wheat, Triticum dicoccoides, the progenitor of modern tetraploid and hexaploid wheats, is an important resource for new variability for disease resistance genes. An accession of T. dicoccoides acc. pau4656 showed resistance against prevailing leaf rust races in India, when tested at the seedling and adult plant stage. The introgression line, developed from the cross of the leaf rust resistant T. dicoccoides acc. pau4656 and the susceptible T. durum cultivar Bijaga yellow, was crossed with T. durum cultivar PBW114 to generate recombinant inbred lines (RIL) for mapping leaf rust resistance gene(s). RIL population was screened against highly virulent leaf rust race 77-5 at seedling stage and inheritance analyses revealed the segregation of two leaf rust resistance genes. The genes have been temporarily designated as LrD1 and LrD2. A set of 387 SSR marker was used for bulked segregant analysis (BSA). The markers showing diagnostic polymorphism in the resistant and susceptible bulks were amplified on whole of the population. Single marker analysis using MapDisto software placed LrD1 on the long arm of chromosome 6A linked to the SSR marker Xwmc256 and LrD2 on long arm of chromosome 2A close to the SSR marker Xwmc632. T. durum cv. PBW114 used in the present study was also resistant to leaf rust at the seedling stage. So one of these leaf rust resistance genes might have been contributed by the PBW114 and other by T. dicoccoides. The current study identified valuable leaf rust resistance genes for deployment in wheat breeding programme.
Vegetable Research Institute AARI, Faisalabad, Pakistan.
Etlas,Amin, , , , , , , , , , , , , , , , , , , , , , , , , , , ,
In the present study five bread wheat genotypes (9797, 9801, 9802, Chakwal-50 and Chakwal-86) were tested in a 5?5 full diallel analysis for the estimation of combining ability for yield and its related traits. In randomized complete block design (RCBD) twenty F1s along with their parents were planted in field with three replications in the research area of Department of Plant Breeding and Genetics, University of Agriculture, during 2014-15. Plant height, No. of grains/spike, spike length, No. of productive tillers/plant, flag leaf area, No. of spikelets/spike, 1000 grain weight and grain yield per plant were studied. Except spike length mean squares due to GCA were highly significant for all the traits. All the characters showed highly significant mean squares for SCA and RCA. SCA variance was lower than GCA variance for number of grains/spike and spike length presenting the major role of additive gene action in the inheritance of these traits. While for plant height, flag leaf area, number of spikelets/spike, number of fertile tillers/plant, 1000 grain weight and grain yield/plant the value of GCA variance was lower than the value of SCA variance exhibiting non-additive gene action. Chakwal-50 was the best general combiner for plant height, spike length, number of spikelets/spike, number of grains/spike and grain yield/plant. The best specific combination for most of the traits was 9802?Chakwal-86. In future wheat breeding research programmes, good specific and general combiners can be exploited.
Agharkar Research Institute Pune
yashavantha kumar,Kakanur, Shrikanth, Khairnar, Balgounda, Honrao, Vijendra, Baviskar, Ajit, Chavan, Vitthal, Gite, Deepak, Bankar, Sameer, Raskar, Satish chandra, Misra, , , , , , , , , , , ,
Heat stress globally remains the most important factor determining yield anomalies. Terminal heat stress shortens the duration of grain filling. Hence, this investigation was undertaken during the cropping season 2016-17 to evaluate heat stress tolerance of 32 bread wheat genotypes planted in timely (optimal temperature) and late (terminal heat stress) sown condition at Agharkar Research Institute, Pune. Data were collected and analyzed for various agronomical and physiological traits and also selection indices for stress tolerance, derived from grain yield of wheat genotypes under optimal and late sowing conditions. It was observed that the genotypes DBW 187, GW 477, HD 2932, DBW 107, PBW 752 were the highest yielding under timely sown condition whereas, HD 3226, DBW 187, HP 1963, HD 3219, DBW 196 were the highest yielding under late sown condition. DBW 187 was found to withstand the stress conditions. Minimum percent yield decrease and high yield stability index (YSI) was found in HD 3219 followed by HD 3226 and DBW 196 which indicated their better performance under stress condition. Harmonic mean, a stress tolerance selection index was found to be the best fit of linear model (R2 = 0.78) and a good indicator of high yield under heat stress condition. Physiological parameters, Chlorophyll (SPAD), canopy temperature (Infra-red thermometer) and vegetation index (NDVI) have not shown significant relation with yield, however, they were found to be significantly associated with yield contributing traits like biomass, thousand grain weight, grain number per spike. DBW 187 and HP 1963 showed stable yields with high PCA 1 and low PCA 2, indicating their resilience to stress conditions. The investigation has resulted in identification of genotypes for terminal heat stress conditions and also given greater insights in understanding the importance of physiological traits and stress tolerance indices in selection process.
Institute of Agricultural Sciences, Banaras Hindu University, Varanasi 221005, India
Vinod Kumar Mishra, Uttam Kumar, Ramesh Chand, Akhilesh Mishra, Arun Joshi
Ug99 is a devastating race of Puccinia graminis f.sp. tritici possessing virulence against resistant genes Sr31 and Sr24. This race is highly adoptive and has spread quite rapidly with 13 known variants covering 13 different countries. For reducing the vulnerability of wheat in south Asia to the Ug99, breeding durable resistant varieties is important. India, second largest wheat producer, falls in the predicted pathway of Ug99. Most of the Indian germplasm possesses Sr31 and Sr24 in their background. HUW468, a well adopted variety of north eastern plains zone (NEPZ) of India, carries durable resistance gene Sr2. To strengthen it, a MABB program was initiated to introgressed two major genes (Sr50 and SrWeb) using a donor line PMBWIR4 from CIMMYT. The foreground selection was performed with Xgwm47 for SrWeb and IB267 for Sr50 followed by the background selection by using 128 polymorphic SSR markers covering all chromosomes. Backcross progenies of HUW468 were screened in the field condition by using of Pgt race 21A-2 at IARI, Regional Station, Indore located in the central India. Superior selected lines from BC2F4:5 generation was planted at three locations in India namely; Varanasi, Indore and Dharwad. HUW468-09-25-47-09 and HUW468-09-25-47-56 were selected from BC2F5 generation having Sr50 and SrWeb along with Sr2 gene, superior agronomic performance and with 93.5% and 92.7% genome recovery, respectively. These two lines also possess 6-10 % yield superiority over the recipient parent HUW468. These lines have been submitted for registration in NBPGR (National Bureau of Plant Genetic Resources), India.
Agricultural Biotechnology Research Institute, Ayub Agricultural Research Institute (AARI), Faisalabad-Pakistan
Imran Habib, Sajid-ur-Rahman, Muuhammad Waqas Jamil, Muhammad Zaffar Iqbal
Rust diseases are among the most important affecting wheat because they are responsible for a significant yield reduction globally. Different types of conventional breeding approaches are currently underway to protect wheat from these diseases. The involvement of molecular genetics and biotechnology tools in conventional plant breeding sets new directions to develop crop varieties with desired traits more efficiently and accurately. An array of molecular markers linked to rust resistant genes and dense molecular genetic maps are now available for use. Marker assisted selection (MAS) is now a routine activity in various crops especially for agronomic traits that are otherwise difficult to tag like resistance to pathogens, insects, nematodes etc. Gene pyramiding involves the stacking of many genes leading to real-time expression of all genes in single variety to develop durable resistance. This method is gaining significant popularity as it would enhance the efficiency of conventional breeding methods and precise development of broad spectrum resistant capabilities. Keeping in view the significance of MAS, rust resistant wheat parental lines were selected and molecular information was tagged using gene linked markers through PCR. Conventional breeding plane was designed on the basis of molecular data and maximum crosses were made between high yielding susceptible and resistant wheat genotypes. Molecular screening and other yield parameters were keenly noted on each stage of segregating population. Three rust resistant genes i.e. Lr-34/Yr-18, Lr-46/Yr-29 and Lr-19 were successfully combined in three cross combinations. Twenty crosses were found positive for two resistant genes i.e. Lr-46/Yr-29 and Lr-19, Moreover, one cross was positive for Lr-34/Yr-18 and Lr-46/Yr-29, and one was positive for Lr-34/Yr-18 and Lr-19. Introduction of more genes is also continued to develop superior resistance against a wide range of rust pathogen in wheat.
Department of Agroecology, Aarhus University, Denmark
Chris Khadgi,S?rensen, Annemarie Fejer, Justesen, Mogens St?vring, Hovm?ller, , , , , , , , , , , , , , , , , , , , , , , ,
Wheat yellow (stripe) rust is a recurrent problem throughout the world, and resistant varieties are an efficient means of managing the disease. Therefore, characterization of diverse sources of resistance is of prime importance for wheat breeding. The objective of the study was to investigate variation in host response in incompatible interactions conferred by different R-genes. Epifluorescence and confocal microscopic methods were utilized for histopathological investigation of six yellow rust R-genes (Yr1, Yr5, Yr6, Yr15, Yr17 and Yr27) in Avocet S background, with Avocet S as the control. Fungal colony size and area of hypersensitive response (HR) were assessed for each interaction at 4, 8 and 16 days post inoculation (dpi). The pattern for Avocet Yr15 was distinct, because HR arrested the pathogen very early and rapidly restricted pathogen growth. Avocet Yr1 and Avocet Yr5 showed a less rapid HR and restriction of pathogen growth, but most colonies were completely surrounded by HR at 8 and 16 dpi. In Avocet Yr6 the size of colonies and the extent of HR were highly variable with continuous change up to 16 dpi. More extensive pathogen growth was observed in Avocet Yr17 and Avocet Yr27, where HR induction was delayed, resulting in large intermingled colonies at 16 dpi. All interactions were clearly different from the susceptible control. Thus each R-gene produced a different temporal and spatial distribution of fungal colonies and HR response. Colony size distributions and HR response patterns are potential parameters for characterization of host resistances with different modes of action in wheat against Pst. The results also expand our comprehension of host resistance in wheat against P. striiformis.
Barani Agricultural Research Station, Kohat
Fida Mohammad, Muhammad Imtiaz
Stripe rust is one of the major limiting factors in wheat production. An objective-based breeding program was initiated at Barani Agricultural Research Station (BARS), Kohat in 2013/14 to transfer APR genes from CIMMYT and ICARDA spring wheat lines into wheat germplasm well adapted in Khyber Pakhtunkhwa (KPK). Nine high yielding but stripe rust susceptible KPK wheat varieties were crossed in various combination with 17 CIMMYT and ICARDA wheat lines carrying resistance genes. The resultant 79 F1s were backcrossed with respective susceptible parents followed by single plant selection in F2 generation. During 2015/16, 367 segregating populations/lines were screened in multi-environment stripe rust tests within Khyber Pakhtunkhwa. Sixty-nine out of 367 lines showing adequate resistance were again screened for strip rust resistance at hot spot and in yield trial at BARS, Kohat during 2016/17. Seventeen lines showed considerable resistance and were higher yielding than check cultivars. Lines exhibiting adequate resistance will be further tested in advanced yield trial at provincial and national level for possible release of new varieties in wheat.