Agriculture Botany Division, Nepal Agricultural Research Council
Baidya Nath,Mahto, Sarala, Sharma, Madan Raj, Bhatta, Mahesh, Subedi, Deepak, Pandey, Nutan Raj, Gautam, Suraj, Baidya, Roshan, Basnet, Rudra, Bhattarai, Ajaya, Karkee, Suk Bahadur, Gurung, Prem Bahadur, Magar, Sunita, Adhikari, Bhagarathi, Shahi, Basistha, Acharya
A total of 41 bread wheat (Triticum aestivum L.) varieties have been released so far in Nepal since 1960. Farmers have been gradually adopting newly released varieties due to disease and lodging resistance, better yield performance and good taste. In Nepal, wheat area coverage, production and productivity have been increased by almost seven, sixteen and two folds, respectively in the last 56 years. Performance of varieties varies from one region to another. Yellow rust is the major problems in hills while leaf rust is the primary issue on the plains. Stem rust is sporadic in localized areas of Nepal. Wheat research program in Nepal has released 9 wheat varieties resistant to Ug99 namely Vijaya, Tilottama, Banganga, Gaura, Dhaulagiri, Danphe, Sworgadwari, Munal and Chyakhura. Vijay, Tilottama and Banganga are also resistant to leaf rust while, Dhaulagiri, Danphe, Sworgadwari, Munal and Chyakhura are resistant to yellow rust. Since the release of Vijay, the first Ug99 resistant variety in Nepal during 2010, source seed production of rust resistant varieties has been increasing significantly each year with present coverage under these varieties being around 40%. WK 1204 has been occupied 35% area in hills of Nepal. Seed production and distribution of such high yielding disease resistant varieties through public-private partnership is leading to quality seed supply for varietal diversity and better food security in the country.
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.
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.
Nepal Agricultural Research Council, National Agriculture Genetic Resources Centre, Khumaltar, Lalitpur
Baidhya Nath,Mahto, Mina Nath, Paudel, Dhruba Bahadur, Thapa, Krishnahari, Ghimire, Bal Krishna, Joshi, Suraj, Baidya, Prem Bahadur, Magar, , , , , , , , , , , , , , , ,
Naked barley (Hordeum vulgare var. nudum L.), is an important winter crop grown in the mountain region of Nepal. Stripe rust (Puccinia striiformis f.sp. hordei), is the most destructive fungal disease of barley in the hills of Nepal with losses up to 100 %, occurring in cooler regions with higher altitude (1000-2500 m). Yield components along with final rust severity (FRS), area under disease progress curve (AUDPC) and average coefficient of infection (ACI) were evaluated for 20 indigenous barley accessions collected from mountainous region of Nepal at National Agriculture Genetic Resource Centre (Genebank), Khumaltar, Nepal during winter season of 2016-2017 with three replications. Barley cultivars displayed a range of severity from 0% to 100% with immune to susceptible reaction. AUDPC values were significantly different among the tested genotypes. Barley genotypes with accession number NGRC00837 (ACI-3), NGRC02357 (ACI-7), NGRC06026 (ACI-9) and NGRC02306 (ACI-12) were found resistant with lowest diseases progress while NGRC02350 (ACI-60), NGRC06036 (ACI-80), NGRC02312 (ACI-86), NGRC04003 (ACI-83) and NGRC02318 (ACI-93) were found as highly susceptible landraces. Correlation coefficients of agronomical parameters such as grains per spike and 1000-kernels weight with epidemiological parameters such as AUDPC and ACI were found highly significant. Resistant genotypes with low values for disease progress as well as diseases reaction were identified. The results indicate that source of resistance to yellow rust in naked barley genotypes are available in Nepal and can be used for resistant breeding in future.
Ethiopian Institute of Agricultural Research (EIAR)
Stripe rust caused by Puccinia striiformis f.sp.tritici, is one of the major diseases of wheat in the world. Experiments were carried out at two sites in Ethiopia (Kulumsa and Meraro) during the 2015 cropping season to evaluate the response of 198 elite bread wheat genotypes and two checks to the prevailing races of stripe rust at adult plant and seedling stage. The genetic profile of these genotypes was assessed using 13006 SNP markers and an association mapping was explored to determine marker?trait association. About 72.5% and 42.5% of the lines exhibited resistance at Kulumsa and Meraro, respectively. Out of 198 genotypes tested in the greenhouse, 31% exhibited common resistance for Kubsa and mixed stripe rust isolate. Only 8966 of the SNPs were polymorphic, only these were used for association mapping analysis. These markers spanned an average density of 3.47 cM per marker, with the poorest density on the D genome. Almost half of these markers were on known chromosomes, but had no position on the consensus map of bread wheat. Analysis of population structure revealed the existence of three clusters and the estimated genomic wide Linkage Disequilibrium (LD) decay in this study ranged from 0 to 50 cM. 53 SNPs in ten genomic regions located on wheat chromosome 1AL, 2AL, 2BL, 2DL, 3BL, 4BL, 4DL, 5AS, 7AL and 7BL were identified. Thirty nine SNP markers in five genomic regions at Kulumsa and 14 SNP markers in six genomic regions at Meraro explained more than 25.5% and 35.1% of phenotypic variability respectively. For seedling stage, 21 markers in ten genomic regions located on wheat chromosomes 1B, 2A, 2B, 3A, 3B, 4B, 4D, 5A, 6B and 7B were associated with resistant. These loci may be useful for choosing parents and incorporating new resistance genes into locally adapted cultivars.
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.
All-Russian Institute of Plant Genetic Resources
Wheat varieties with single effective gene for leaf rust resistance often quickly become susceptible because of multiplication of virulent Puccinia triticina genotypes. One of the methods to elongate term of effectiveness is to combine two genes in host genotype. To note, it is impossible to distinguish phenotypically plants or families having one or two genes in hybrid populations; the only method is to use PCR producing DNA markers linked to each gene for resistance. It is not convenient when necessary to analyze thousands plants or especially families of crosses between carriers of certain genes. At inoculation of wheat seedlings having Lr 9, 19, 24, 47, 29 and Sp with rust population from North-West region of Russian Federation all of them were absolutely resistant, so these genes may be considered to be effective in this region. Rust population was multiplied on cv. Leningradka leaf segments placed on cotton wool wetted with solution of maleic acid hidrazide (10 mg/l) + potassium chloride (0.48 g/l) +monosubstituted sodium phosphate (0.66 g/l) and used to infect seedling of the lines constantly poured with the solution. Rare pustules were recorded on each line. Isolates from the line were combined, multiplied and used to infect the lines set. Interaction specificity was shown for carriers of certain genes for resistance and inoculums. We propose to infect seedlings of hybrid wheat populations with mixtures of isolates virulent to first gene and those virulent to second one at use of above-mentioned method to multiply rust and grow plants. Seedlings resistant to that inoculum have both genes for resistance. If we have F3 or later families it is possible to use original population without selection of virulent isolates; in this case the method allowed removing progenies of heterozygous plants. With this approach we developed lines possessing combinations of Lr9+Lr24 and Lr9+Lr47 genes
Department of Plant Sciences, University of the Free State, South Africa
Marcel Meyer, Robert Park, Christopher Gilligan, Laura Burgin, Matthew Hort, David Hodson, Zacharias Pretorius
Despite being 10,000 km apart, the current study emphasizes the potential vulnerability of Australia to wind-borne Puccinia graminis f. sp. tritici (Pgt) spore introductions from southern Africa. Of four Pgt introductions into Australia since 1925, at least two (races 326-1,2,3,5,6 and 194-1,2,3,5,6) are thought to have originated from southern Africa. Microsatellite analysis of 29 Australian and South African Pgt races confirmed close genetic relationships between the majority of races in these two geographically separated populations, thus supporting previously reported phenotypic similarities. Using Lagrangian Particle Dispersion Model simulations with finely-resolved global meteorological data over a 14-year period and a three-day urediniospore survival time, the study showed that long distance dispersal of Pgt from southern Africa to Australia is possible, albeit rare. Transmission events occurred most frequently from central South Africa, but were also possible from southern South Africa and Zimbabwe; while none occurred from a representative source-location in Tanzania. Direct dispersal incursions into both the western and eastern Australian wheat belts were feasible. Together, the genetic and simulation data strongly support the hypothesis that earlier introductions of Pgt into Australia occurred through long-distance wind-dispersal across the Indian Ocean. The study thus acts as a warning of possible future Pgt dispersal events to Australia which could include members of the Ug99 race group. This emphasizes the continued need for Pgt surveillance on both continents.
Plant Pathology Division, Nepal Agricultural Research Council
Baidya Nath Mahto, Durba Bahadur, Thapa Roshan, Basnet Nautan Raj, Gautam Sesh, Raman Upadhyaya
Disease surveillance is very important in establishing the status of disease response in crops. During the 2014 to 2016 wheat seasons, foliar blight (spot blotch caused by Bipolaris sorokiniana and tan spot caused by Pyrenophora tritici-repentis) was recorded as severe across the entire whole plains region. Foliar blight was moderate in the mid hills, especially the Kathmandu valley. Leaf rust was severe (10MS - 100S) at several places in the mid hills. This could be due either to climatic conditions or varieties susceptible to the prevailing pathotypes. Yellow rust was also recorded up to 100S in the Kathmandu valley. Newly released varieties Gaura and Dhaulagiri showed yellow rust incidence of 20MS to 40S. Stem rust was sporadic and light and was observed very late in the season (tR - 10MR) in far western districts and the Kathmandu valley. Powdery mildew was moderate and localized. Loose smut was found at low levels throughout the mid hills. In 2014, Karnal bunt (caused by Tilletia indica) was also recorded in far western regions. Five different pathotypes of P. triticina (121R63-1, 21R55, 21R63 and 0R9) and one Pst pathotype (110S119) have prevailed during the last few years. Wheat genotypes were evaluated at Khumaltar and those reputed to have Yr27, Yr27+, Yr27+Yr18, Yr31+APR, Yr9, Yr10 and Yr15 were resistant. Similarly, genotypes containing Lr34+ had lower leaf rust severities than others.
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.