Research Center of Agricultural and Development in Northwest Semi-arid regions of Tunisia
Afef,OTHMANI, Olfa, SLAMA-AYED, Hajer, SLIM-AMARA, Mongi, BEN YOUNES, , , , , , , , , , , , , , , , , , , , , ,
Eleven durum wheat (Triticum durum Desf.) genotypes were screened to select for drought-tolerance under in vitro immature embryos culture. Drought stress is induced by using five PEG concentrations (0, 200, 270, 295 and 310 g/l of PEG 6000). Results showed, for all studied traits, significant differences among PEG treatments and genotypes. In fact, increasing PEG concentration decreases relative growth rate, callus water content, relative water content, in vitro tolerance and relative tolerance. Biplot analysis indicated that the first two PCs (principal components 1 and 2) explain 70.5 % and showed that Karim, Mahmoudi and Om Rabiaa are respectively the most drought tolerant varieties tested, however, Ben Bechir, Maghrbi and Nasr were the most sensitive.
Instituto Nacional de Investigaci?n Agropecuaria (INIA)
Clara,Pritsch, Gustavo, Azzimonti, Silvia, Pereyra, Mart?n, Quincke, Victoria, Bonnecarrere, Paula, Silva, Ariel, Castro, Bettina, Lado, Silvina, Bar?ibar, Richard, Garc?a, Silvia, Germ?n, , , , , , , ,
Stem rust (SR) and Fusarium head blight (FHB) threaten the sustainability of wheat production worldwide. Sr2 is a widely used gene conferring partial, but durable, resistance to SR. Fhb1 confers a significant level of FHB resistance, but is poorly represented in the INIA-Uruguay wheat-breeding program. Sr2 and Fhb1 are linked in repulsion (~3 cM apart) on chromosome 3B. However, lines with Sr2 and Fhb1 in coupling were recently developed at the University of Minnesota, USA (kindly provided by J. Anderson). In order to incorporate Sr2/Fhb1 into Uruguayan elite wheat cultivars the donor line was crossed and backcrossed with four cultivars lacking both genes and expressing an intermediate to low level of resistance to SR and FHB: G?nesis 2375, G?nesis 6.87, INIA Madrugador, and INIA Don Alberto. Genotypes carrying Sr2/Fhb1 were selected using molecular marker UMN10; 250 BC2F1 were obtained for each recurrent parent. BC3F1 plants positive for UMN10 will be selected. The effect of Sr2/Fhb1 on response to SR and FHB in the different genetic backgrounds will be quantified by comparing disease severities of BC3F2 homozygotes with and without the UMN10 marker. Hopefully the introduction of Sr2/Fhb1 will contribute in reducing the risk of SR and FHB in wheat crops in Uruguay.
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.
University of Mohammed V/ICARDA
HAFSSA,KABBAJ, AYED, AL ABDALLAT, GREGOR, GORJANC, JESSE, POLAND, MIKAEL, MILOUDI NACHIT, AHMED, AMRI, BOUCHRA, BELKADI, KARIM, FILALI MALTOUF, FILIPPO, BASSI MARIA, , , , , , , , , , , ,
Durum wheat (Triticum durum Desf.) is a major stable crop and it represents a base of the Mediterranean diet. This region is subject to a Mediterranean climate, which is extremely unpredictable with severe changes in moisture and temperature occurring each crop season. This unpredictability is summarized by breeders as GxE and the identification of traits controlling this interaction is quintessential to ensure stability in production season after season. To study the genetics of yield stability, four RILs populations derived from elite x elite crosses were assessed for yield and 1,000-kernel weights across five diverging environments in Morocco and Lebanon. These 550 RILs were characterized with 4,909 polymorphic SNPs via genotyping by sequencing. A consensus map was derived by merging the individual genetic maps of each population. Finally, imputation was used to fill all the missing haplotypes and reach a reduction of missing data to below 8%. Several significant QTLs were identified to be linked to TKW, grain yield and a stability index, namely AMMI wide adaptation index (AWAI). A second approach to identify loci controlling stability was the use of a global panel of 288 elites, accessions and landraces tested in 15 diverging environment. Multi-locations data were compiled via GxE models to derive the AWAI stability index. In addition, this panel was characterized with 8,173 polymorphic SNPs via Axiom 35K array. Significant associations were identified for all traits, including QTLs unique to AWAI. The sum of the identified QTLs can now be pyramid via marker assisted selection and molecular designed crosses in order to obtain very stable cultivars.
Turkey-ICARDA Regional Cereal Rust Research Center (RCRRC), ICARDA, Menemen, Izmir, Turkey
Muhammad Massub Tehseen, Ezgi Kurtulus, Maha Al Ahmed, Ahmed Amri, Mariana Yazbek, Ali Shehadeh
In 2016 the bread wheat (BW) and durum wheat (DW) landrace accessions were evaluated against PstS2 and in 2017 against a mixture of PstS2 and warrior race in field inoculations at Izmir precision stripe rust phenotyping platform. Inoculation was carried out three times during seedling, tillering and booting stages using mixture of fresh spore and talcum powder. Adult-plant responses of tested accessions were recorded according to 0-9 scale once the flag leaf of the susceptible cultivar became fully susceptible. During 2016, out of 3319 BW accessions, 1135 (36%), 871 (28%) and 1133 (36%) were found resistant (1-3 scale), moderately resistant (4-6), and susceptible (7-9) to PstS2, respectively. Amongst the resistant accessions in 2016, 1043 (33%) remained resistant while 786 (25%) showed moderate resistant and 1310 (42%) became susceptible. In 2017, 43% of moderately resistant accessions showed susceptibility to warrior race and 57% remained resistant to moderately resistant. Within the susceptible accessions to PstS2 race in 2016, 22% showed resistance to the warrior race and the remaining were susceptible. In case of DW in 2016, 76% (553) of the accessions were resistant to PstS2, 23% (163) were moderately resistant and only 1% (7) were found susceptible. In 2017, 329 (46%) of the resistant accessions were found resistant, whereas 289 (40%) and 105 (15%) showed moderately resistance and susceptible reaction to Warrior race, respectively. The present data indicated that BW landraces were generally more susceptible to stripe rust than DWs. Susceptibility of both BW and DW accessions to Warrior race indicated that most likely some of the uncharacterized resistance genes which conferred resistance to PstS2 were ineffective against the warrior race. Sources of resistance to both races were identified in both BW and DW. Genetic architecture of identified sources of resistance in present study requires further investigations.
University of Georgia
Mohamed,Mergoum, Yuanfeng, Hao, Jerry, Johnson, Dan, Bland, James, Buck, John, Youmans, Benzamin, Lopez, Steve, Sutton, Zhenbang, Chen, , , , , , , , , , , ,
Leaf rust disease, caused by the fungal pathogen Puccinia tritcina, is the most destructive foliar disease of wheat worldwide. Gene combination of Lr37/Yr17/Sr38 has been used in Georgia (GA) to prevent the loss from leaf rust; however, with the emergence of new virulent races, these genes have lost their effectiveness. 'AGS 2000' and 'Pioneer 26R61' are the most common soft red winter wheat (SRWW) cultivars in Southeastern US, and have been used as good sources of resistance to leaf and stripe rusts, and powdery mildew. To characterize the genetic basic of resistance of AGS 2000, a mapping population of 178 recombinant inbred lines (RIL) has been developed from a cross with Pioneer 26R61. This population was genotyped using a combination of SSR, DArT, and SNP markers, and a total of 2734 markers covering the entire genome were used for the construction of genetic map. Phenotypic evaluation of parents and RIL population was conducted at the seedling stage using a virulent GA leaf rust race. QTL mapping revealed a major QTL on chromosome 2BL, explaining about 20% of total phenotypic variation in AGS 2000. Additionally, a minor QTL was also detected on chromosome 5B. QTL on 2BL was identified as a novel gene, and can be used in marker-assisted selection for leaf rust resistance.
Wheat Research Institute, Ayub Agricultural Research Institute,Faisalabad,Pakistan
Mehvish,Makhdoom, Javed, Ahmad, Makhdoom, Hussain, Iqra, Ghafoor, , , , , , , , , , , , , , , , , , , , , ,
Wheat crop is facing immense losses each year owing to climate change, eventually being major threat to global food security. So, the objective of the present study was to screening of advance lines under drought and heat stress conditions. In following study, 30 advance lines of wheat along with four checks(Faislabad-08, Millat-11, Galaxy-13 and ujala16) with three treatments (heat, drought, normal) were tested for different morphological (days to heading, plant height, days to maturity, biomass,1000 grain weight and grain yield) and physiological (canopy temperature at vegetative & reproductive stage, NDVI vegetative & reproductive), parameters. Biplot analysis depicted that V2, V3, V8, V14, V19, V25, and V30 showed the highest OP vector for grain yield in drought environment. Whereas, under heat conditions, V3, V4, V5, V10, V11, and V12 displayed their maximum longest vector for grain yield. Correlation analysis depicted that grain yield had non-significant correlation with canopy temperature (vegetative stage), normalized difference vegetation index (vegetative stage) canopy temperature (reproductive stage), plant height, days to heading and days to maturity under heat stress environment, while it had significant association with biomass and thousand grain weight. Under drought environment, grain yield had positive and significant correlation with biomass while on the other hand it had negative but significant association with normalized difference vegetation index (reproductive stage) and canopy temperature (reproductive stage). Best performing lines could be efficiently exploited in research programs to evade the perilous impact of climate change.
Plant Pathology Research Institute
,, , , , , , , , , , , , , , , , , , , , , , , , , , , ,
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.
Chris K. Sørensen, Rodrigo Labouriau, Annemarie Justesen, Mogens Hovmøller
Host vernalisation and temperature strongly affect the susceptibility of winter crops to pathogenic fungi. However, how the interaction of these environmental factors influence host susceptibility to Puccinia striiformis, the yellow (stripe) rust fungus, is poorly understood. An experimental system was developed to examine the effect of vernalisation, temperature regime (standard; 18 day/12 night °C and low; 12 day/6 night °C) and plant growth (seedling and adult plant stages) on changes in susceptibility of agronomically important winter wheat and triticale genotypes to P. striiformis races ('Warrior' and 'Kranich') highly predominant in several European countries. Host genotypes exposed to prolonged periods of low temperature, termed vernalisation, reduced disease susceptibility on specific winter host genotypes, although its effect differed considerably by the temperature regime and the P. striiformis race deployed. The influence of vernalisation on host susceptibility was more apparent at low temperature for the 'Warrior' race and at standard temperature for the 'Kranich' race. Triticale genotypes inoculated with the 'Kranich' race were particularly affected by the influence of vernalisation and temperature regime by displaying a shift towards reduced susceptibility at standard temperature. The effect of plant growth stage, i.e., vernalised seedlings versus adult plants, was most evident for the 'Warrior' race at standard temperature and at low temperature for the 'Kranich' race by revealing a lower infection type at the adult plant stage. The research findings presented here contributed to a better understanding of the role of environmental factors in host susceptibility. This, in fact, will aid in the development of more efficient early-warning systems and disease management strategies to the yellow rust fungus and in the decision making for the deployment of winter wheat and triticale genotypes.
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.