ICAR-Indian Institute of Wheat and Barley Research
Sudheer Kumar, P.L. Kashyap, Gyanendra Pratap Singh
Yellow rust of wheat caused by Puccinia striiformis Westend. is one of the important diseases of wheat in India. In north Indian states it spreads quite fast due to favourable temperature and moisture prevailing in these states during major part of crop growth (November-mid March). In spite of favourable weather, proactive survey and surveillance and advisories issued in time resulted successful management of yellow rust in India during past four decades. Even large scale cultivation of varieties like HD 2967 in about 12 million ha past two years did not result any losses. Three spots of initial foci near foot hills in Punjab have been identified and are monitored regularly. Any sign of yellow rust is controlled effectively with the foliar sprays of fungicides like propiconazole @ 0.1%. Use of mobiles phones and internet services is regularly done for transfer of information on wheat crop health and suggestions for proper management. Strategic planting and sowing of wheat in which newly released high yielding yellow rust varieties helped in reducing the yellow rust inculum build up. Regular monitoring of wheat health via weather forecasts take place after every fortnight from December to March. During 2016-17 crop season, yellow rust was effectively managed and its occurrence was delayed in Punjab, Haryana and Uttarakhand states. Two new pathotypes, 110S 119 and 110S 84 developed recently were used for evaluation of entries of wheat yield trials during 2016-17 at hot spot locations. The new varieties in pipe line of identification and release are tested against yellow rust. The most critical period for yellow rust management remained from December till mid February.
Wheat Research Centre, Bangladesh Agricultural Research Institute
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The soils of the entire Sylhet region of Bangladesh are strongly acidic where lands remain fallow during winter season due to scarcity of irrigation water required for rice cultivation. There is a scope of wheat expansion in this region as the water requirement of wheat is less than Boro rice. Field experimens were carried out at South-Surma, Sylhet, in 2012-13 and at FSRD site Jalalpur, Sylhet in 2013-14, in collaboration of WRC and OFRD. BARI examined the response of seven wheat varieties at two levels of lime in split-plot design where lime was applied in main plots and different wheat varieties were grown in sub-plots. The seeds were sown on December 05, 2012 and November 30, 2013 for the growing season of 2012-13 and 2013-14, respectively. The wheat varieties used in this study were Shatabdi, Sufi, Sourav, Bijoy, Prodip, BARI GOM 25 and BARI GOM 26. The index of relative performance of each variety in comparison to mean yield of all varieties under the contrast conditions of liming and non-liming was estimated to determine relative adaptability of wheat variety under experimental soil conditions. The result indicated that most of the yield components viz. spikes/m2, thousand grain weight and grain yield of wheat were significantly improved by liming for both the years and locations. There were variations in lime response among the wheat varieties. The index of relative adaptability (IRA%) for yield of BARI GOM 26 and Bijoy was more than 100% for both the years. The result indicated that these two wheat varieties are relatively tolerant to low pH and could be adapted in acidic soil of Sylhet.
Institute of Agricultural Environment and Resources, Yunnan Academy of Agricultural Sciences, China
Xianming Chen, Anmin Wan, Jiasheng Chen, Mingliang Ding
Wheat stripe rust (Puccinia striiformis f. sp. tritici, Pst) is the most destructive disease of wheat worldwide. Breeding and planting resistant cultivars is the most economic, effective, as well as environmental methods to control the disease. Yunnan is a severe epidemic zone in China, which provides new incursions for other parts of China. Study on virulence of the Pst population and effectiveness of resistance genes, will provide information for breeding and rational use of resistance genes. One hundred and thirty-six136 isolates collected from 9 regions of Yunnan were tested using a set of 18 Yr NILs with genes Yr1, Yr5, Yr6, Yr7, Yr8, Yr9, Yr10, Yr15, Yr17, Yr24, Yr27, Yr32, Yr43, Yr44, YrSP, YrTr1, YrExp2, YrTyTye. Stripe rust races were named by octal code. The results showed that the Pst population in Yunnan is highly variable in races and virulence. A total of 64 races were identified and the top two most frequent races were 550273 (Virulence/Avirulence formula: 1, 6, 7, 9, 27, 43, 44, SP, Exp2, Tye / 5, 8, 10, 15, 17, 24, 32, Tr1 and 550073(Virulence/Avirulence Formula: 1, 6, 7, 9, 43, 44, SP, Exp2, Tye / 5, 8, 10, 15, 17, 24, 27, 32,Tr1), with frequency of 28.68% and 11.76%, respectively. The remaining races had frequencies less than 5.0%. No virulence were found for Yr5, Yr10, Yr15, and Yr32. The frequencies of virulence to Yr24, YrTr1, Yr8, and Yr17 ranged from 0.74% to 11.76%. The frequency of virulence to Yr27 was 52.94%; and virulence to Yr1, Yr6, Yr7, Yr9, Yr43, Yr44, YrSP, YrExp2, and YrTye ranged from 79.94% to 91.91%. The results will guide the breeding and wheat production. (This study was supported by National Natural Science Foundation of China, Grant No. 31260417 and 31560490)
Leonardo,Crespo-Hererra, Julio, Huerta, Ravi, Singh, , , , , , , , , , , , , , , , , , , , , , , ,
Malnutrition affects more than 2 billion people across the globe, particularly zinc and iron deficiency causes major health problem in developing world. The biofortified staple food crops such as wheat, is an important channel to contribute to the hidden hunger problem in low income countries. Breeding for enhanced zinc concentration in wheat was initiated by crossing high zinc sources identified among synthetic wheats, T. dicoccum, T. spelta and landraces. These crosses have resulted in wheat varieties with competitive yields and enhanced grain zinc were adapted by farmers in South Asia. CIMMYT-derived early-maturity wheat cultivar 'Zinc-Shakti' with about 40% increased zinc (+14 ppm), is now grown in eastern India through public-private partners. The two CIMMYT-derived biofortified varieties: 'WB2' and 'HPBW01' released in 2016 for northwestern plains zone of India. In Pakistan, 'Zincol' was released in 2016. The first high zinc wheat variety (Bari-Gom 33) with better resistance to wheat blast have been released in Bangladesh for commercial cultivation in 2017. Targeted crosses with increased population sizes were used to obtain superior progeny lines that have high zinc levels in combination with other essential traits. This has resulted in the incorporation of several novel alleles for grain zinc and iron in elite, high-yielding germplasm. High zinc and iron are under quantitative genetic control and further progress is possible as multiple QTL are pyramided in high yielding wheats. High-throughput, non-destructive phenotyping for grain zinc and iron using the X-ray fluorescence (XRF) analysis has facilitated the selection dramatically. Gene discovery and mapping studies leading to the utilization of markers to further improve the breeding efficiency. Rapid adoption of high zinc wheat varieties in South Asia and beyond is expected with the second wave of high zinc wheat lines with superior yield, heat and drought tolerance and resistance to rusts and other foliar diseases.
Instituto Nacional de Investigaci?n Agropecuaria (INIA) La Estanzuela
Paula Silva, Clara Pritsch, Miguel Raffo, Silvia Pereyra, Silvia German
Wheat stem rust (SR), caused by Puccinia graminis f. sp. tritici, (Pgt) is considered one of the most destructive diseases of the wheat crop. As Sr24 and Sr31 are the most widely used resistance genes in the Southern Cone of America, wheat crops in this region is under threat of SR outbreaks posed by the potential migration of virulent Pgt Ug99-lineage races (Ug99+). Efforts have to be made to develop adapted lines resistant to Ug99+. Genes Sr26, Sr32 and Sr39 are effective to both Ug99+ and local races of the pathogen. This work is aimed to pyramid two and three of the resistance genes in two locally adapted wheat cultivars (G?nesis 2375 and G?nesis 6.87). Donor lines of Sr26, Sr32 and Sr39 (developed by I. Dundas, University of Adelaide, Australia) and molecular markers Sr26#43, csSr32#1 and Sr39#22r (developed by R. Mago et al., University of Adelaide) were used. Lines with two-gene combinations were developed in two steps. First, tree-way crosses were made by crossing heterozygous F1 plants (derived from crossings donor lines) to either one of the two adapted wheat cultivars. Subsequently, tree-way F1 plants were genotyped and only those with two-gene combinations were backcrossed (BC) twice to the adapted cultivars. Among three-way F1 plants, two-genes combinations were confirmed for Sr26+Sr32 (8 out of 31), Sr26+Sr39 (2 of 115) and Sr32+Sr39 (26 out of 103). In the BC1F1 generation, Sr26+Sr32, Sr26+Sr39 and Sr32+Sr39 combinations corresponded with 9, 9 and 45 out of 99, 27 and 241 plants, respectively. In 2017, 1345 BC2F1 plants are being grown to obtain BC2F2. We plan to intercross plants with two-gene combinations to obtain lines with the three genes which will be used as sources of resistance to develop cultivars with presumably longer lasting resistance to wheat SR.
University of the Free State, South Africa
Nelzo Ereful, Botma Visser, Lesley Boyd, Zakkie Pretorius
Adult plant resistance (APR) to stem rust, caused by Puccinia graminis f. sp. tritici (Pgt), is often conferred by multiple minor genes and has the potential to be durable. A preceding project identified two Kenyan wheat lines (W1406 and W6979) from the Genome Resource Unit (Norwich, UK) that exhibit APR to Pgt. The aim of this study was to investigate the APR response to Pgt race PTKST in W1406 and W6979 compared to 37-07, a susceptible control line. Histological investigation of inoculated flag leaf sheaths indicated a significant and quantifiable decrease in Pgt colony size in the APR lines at 120 hours post inoculation (hpi). Molecular analysis supported the observed fungal biomass decrease in the APR lines at 120 hpi. RNAseq analysis identified 169 transcripts differentially expressed in W1406 and 166 transcripts in W6979 when comparing 24 and 72 hpi to 0 hpi. In W1406 transcripts encoding putative pectinesterases, lipid-transfer proteins and leucine-rich repeat-like proteins were induced at 72 hpi. In W6979 only a corresponding putative pectinesterase encoding transcript was identified. Although the induced defence response in the two APR lines exhibited some dissimilarity, it potentially involves cell wall modification in both lines. Two independent sets of peroxidases were induced at 24 and 72 hpi in both lines, suggesting independent signalling events. Expression analysis suggests the occurrence of two phases of gene expression, one at 24 hpi and another at 72 hpi; the latter seeming to correspond to the inhibition of Pgt growth, manifesting as the observed APR phenotype.
ICAR- Indian Institute of Wheat & Barley Research, Karnal-132001, India
Vinod Tiwari, DP Singh, RP Gangwar, GP Singh
The changing climatic conditions are affecting wheat production in major agro-ecological zones in India, namely, north western plains(NWPZ), north eastern plains(NEPZ), central (CZ) and peninsular zone(PZ) where the reproductive phase has to endure higher temperatures. Also, the prevalence and virulence of rust pathotypes and other diseases are affected. To address such challenges, development of wheat for climate resilience was initiated following shuttle breeding approach for incorporating heat stress tolerance as well as resistance to wheat rusts. During 2010-16, a total of 583 elite lines were evaluated against prevalent pathotypes of stripe rust 78S84, 110S119, 110S84 and 46S119; leaf rust 12-2(1R5), 12-5(29R45), 77-2(109R31-1), 77-5(121R63-1), 77-9(121R60-1) and 104-2 (21R55) and stem rust 11(79G31), 40A(62G29), 42(19G35), 122(7G11) and 117-6(37G19) of which 108 promising entries were identified. These lines were evaluated for disease response in multilocational Initial Plant Pathological Screening Nursery (IPPSN) against prevalent races of all three rusts. Based on average coefficient of infection (15.0 ACI), 42 (39%), 104 (96%) and 90(83%) entries were found resistant to different races of stripe, leaf and stem rusts, respectively. Based on performance in multiplication yield trials, 29 entries were contributed in national coordinated evaluation system on Wheat & Barley which resulted in release of four wheat cultivars DBW71(Yr9+27+,Lr26+,Sr2+5+31+), DBW107(Yr9+,Lr26+3+,Sr31+), DBW110(Yr2+, Lr13+10+,Sr13+11+) and DBW93(Yr9+, Lr26+23+, Sr31+) for commercial cultivation in NWPZ, NEPZ, CZ and PZ, respectively. These cultivars are becoming popular among farmers due to their yield advantage, resistance to diseases, tolerance to high temperature and better quality traits. Also, DBW 129 was screened in multiple disease screening nursery (MDSN) and observed resistant to all rusts, leaf blight, powdery mildew, flag smut and shoot fly. The adoption of the newly developed cultivars for deployment of differential genes for resistance would lead to reduction in disease pressure and bring higher profitability to farmers in different agro-ecological zones in India.
Agricultural Biotechnology Research Institute, AARI, Faisalabad PAKISTAN
Shahid Nazir, Muhammad Waqas, Jamil Imran, Habib Muhammad, Zaffar Iqbal
Wheat is a major staple food in Pakistan and its production is subject to many yield limiting factors. Among biotic stresses, rusts have been the most devastating. Hence, the development of rust resistant genotype is the ultimate solution. The traditional approach of transferring resistant genes from wheat related species is time-consuming and laborious. It is complicated by the need to perform inoculation tests on plants in segregating populations, also requiring the application of appropriate races. Molecular markers could tag the presence of important resistance genes and allow breeders to identify the resistance genes rapidly and accurately. Therefore, use of molecular markers can help breeder in developing resistant wheat cultivars to minimize yield losses. To harvest the beauty of this system, 60 candidate wheat candidate varieties (included in provincial wheat yield trial) were screened against rusts using linked DNA markers for genes i.e. Lr-34/Yr-18, Lr-46/Yr-29, Lr-28, Lr-19, Sr-2 and Sr-32. Total genomic DNA was isolated and used as template in PCR for the verification of rust resistant genes. The gene Lr-34/Yr-18 was found present in one genotype and absent in 54 genotypes whereas one genotype was observed as heterozygote with respect to this gene. 49 candidate varieties for Lr-46/Yr-29, 03 for Lr-28, 56 for Lr-19, 38 for Sr-2 and 54 for Sr-32 were found positive showing presence of these genes in the new varieties. Missing entries were tested twice but no resistant gene(s) was detected. This information was shared with respective breeding institute to design the future research program. Furthermore, this molecular information was used for rust resistant gene pyramiding work to develop the durable resistance in wheat against rusts and crosses were attempted utilizing high yielding genotypes and genotypes carrying maximum rust resistance genes.
State Key Laboratory of Crop Stress Biology for Arid Areas and College of Life Sciences, Northwest A&F University, Yangling
Liyang Chen, Baoyu Huai, Shoujun Hu, Lijing Pang, Pu Yuan, Zhensheng Kang
Infection of pathogens in plants induces production and accumulation of reactive oxygen species (ROS). ROS are not only involved in plant defense responses, but directly restrict or kill pathogens. To counteract this attack, it is necessary for pathogens to remove host-produced ROS. However, the mechanisms protecting pathogens against host-derived oxidative stress are little known. In this study, a superoxide dismutase (SOD) gene, PsSOD2, was cloned from Puccinia striiformis f. sp. tritici (Pst). Quantitative reverse transcription PCR (qRT-PCR) analysis indicated that PsSOD2 is an in-planta induced gene active in the early stage of Pst infection. Prokaryotic expression and biochemical characterization revealed that PsSOD2 encoded a Cu-only SOD. The predicted signal peptide for protein secretion was functional in an invertase-mutated yeast strain. Transient expression in Nicotiana benthamiana suggested that PsSOD2 is localized in plasma membrane and dependent on glycophosphatidyl inositol (GPI) anchor at the C terminus. Furthermore, Size exclusion chromatography and bimolecular fluorescence complementation validated dimerization of PsSOD2. Overexpression of PsSOD2 in N. benthamiana significantly decreased ROS production triggered by flg22. Knockdown of PsSOD2 using a host-induced gene silencing (HIGS) system reduced the virulence of Pst, which was correlated to ROS accumulation in HIGS plants. These results suggest that PsSOD2 is a pivotal virulence factor that is localized in hyphal plasma membrane to promote Pst infection by scavenging host-derived ROS.