National Agronomic Institute of Tunisia
FATMA,BEN JEMAA, HAJER, SLIM-AMARA, , , , , , , , , , , , , , , , , , , , , , , , , ,
Wild species with valuable genetic heritage was used long time ago in interspecific crosses to improve cultivated plants adaptation to environmental constraints. The objective of this study is to transfer the salinity tolerance of Hordeum marinum, a wild barley species, to three durum wheat varieties (Karim, Razzek and Nasr) by intergeneric crosses. In order to skip the incompatibility between these species, in vitro immature embryo rescue was performed using B5 medium (Gamborg et al., 1968). The results showed that the genotype has an important effect on the success of the crosses and the rate of regenerated plants. We have found that 34.21% of the embryos derived from hybridization Razzek x Hordeum marinum has regenerated haploid plantlets, 5.88% for Karim x Hordeum marinum cross, and 2.78% for Nasr x Hordeum marinum.
The obtained chromosomal stock of the hybrid haploid plants was doubled by colchicine treatment concentrated at 0.05%. The rate of doubled haploid plants were reduced after colchicine treatment to 26.32% for Razzek x Hordeum marinum cross, 0% for Karim crossed with Hordeum marinum and remained unchanged for Nasr x Hordeum marinum.
The doubled haploids obtained are subjected to salt stress (6-12 g/l) in order to evaluate their tolerance to salinity.
The Ohio State University
Nelly Arguello-Blanco, Mao Huang
Genomic selection facilitates rapid cycling through a breeding cycle by eliminating the need to phenotype prior to selecting superior parents and crossing among them. In winter wheat we can now complete a cycle of GS in about 12 months and two greenhouse seasons. Season consists of planting F1s from the previous cycle and selfing to obtain F2 seed. The second season involves planting and genotyping the F2s, predicting their value with GS, selecting and crossing the best, and harvesting the F1 seed. Our breeding program has completed five cycles of GS in one population primarily for grain yield, over the past five years. We have completed three cycles of GS for resistance to Fusarium Head Blight in a second population. Genotyping was done using genotyping-by-sequencing. This provides an opportunity to assess the changes in the population that have occurred as a result of this rapid cycling. These include 1) changes in genomic estimated breeding values for grain yield and FHB resistance, 2) effect of selection and drift on allele frequencies including fixation, 3) effect of selection on diversity and genetic relationships, and 4) changes in linkage disequilibrium. We are conducting these analyses and will present the results.
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.
Plant Pathology Research Institute
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Leaf rust resistance genes Lr9 and Lr19 were previously highly effective against the most predominant races of Puccinia triticina in Egypt. In 2015/2016 growing season, susceptible field reaction was recorded on these two genes where rust severity reached about 40S for Lr9 and 5S for Lr19 under Egyptian field conditions at four locations i.e. El-Behira, El-Minufiya, El-Qalubiya and El-Fayom governorates. Eight leaf rust field samples were collected from these governorates (four from each of Lr9 and Lr19). Forty single isolates were derived from the collected samples of Lr9 and Lr19 (each with 20 isolates). Eight pathotypes were identified from Lr9 and only two pathotypes were identified from Lr19. The most frequent pathotypes virulent to Lr9 were KTSPT (30%) followed by TTTMS (25%). Moreover, the other pathotypes ranged from 5 to 10%. Whereas, the most frequent pathotype virulent to Lr19 was CTTTT (85%) and the lowest PKTST was 15%. Pathotypes i.e. PRSTT, NTKTS and TTTMS identified from Lr9 were more aggressive on most of the tested leaf rust monogenic lines, as they were virulent to 36, 35 and 35 lines, respectively from a total of 39 lines. The two pathotypes; PKTST and CTTTT identified from Lr19 were virulent to 36 and 35 lines, respectively. Moreover, leaf rust pathotypes i.e. NPTNK and PRSTT from Lr9 and PKTST from Lr19 were the most aggressive on the tested wheat cultivars at seedling stage. The Lr2a was the most effective leaf rust resistance genes against the tested pathotypes at adult plant stage. Wheat cultivars Misr 1, Misr 2 and Nubariya 1 were the most resistant cultivars against the tested pathotypes at adult plant stage.
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.
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.
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.
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.
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.