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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.
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.
In India, wheat crop is a major contributor to the agricultural economy of India, occupying 30.7 mha area with 98.38 mt production. Stripe or yellow rust is a constraint to wheat production on about 12.0 m ha in the Northern Hills and North Western region of India. Varieties resistant at the time of release become susceptible usually within a few years due to new pathogen races. The present study conducted in 2015-16 was undertaken to identify stripe rust resistant genotypes among a set of 146 advanced breeding lines and popular cultivars. All genotypes were planted in two replications in northern India at ten locations viz., Karnal, Hisar (Haryana), Ludhiana, Gurdaspur (Punjab), Malan, Bajoura, Dhaulakuan (Himachal Pradesh), Pantnagar (Uttarakhand), Durgapura (Rajasthan), Jammu (J & K) and Delhi. After every 20 genotypes, infector (susceptible cultivar to both pathotypes) was planted. All genotypes were inoculated with mixture of prevalent Pst races 78S84 (Yr 27 virulence) and 46S119 (Yr 9 virulence) at Karnal. Out of 58 released cultivars grown in different zones of the country, fifteen lines (HS 507, DBW 90, HD 3086, WH 1080, WH 1124, WH 1142, HD 4728, HI 8498, HI 8737, MPO 1215 (D), NIDW 295 (d), UAS 428 (D), UAS 446 (D), DBW 71, KRL 210) showed stripe rust ACI < 10.00 (average coefficient of infection). But among advance 88 wheat lines, there was good level of resistance in 50 lines (ACI <10.00). Lines having AUDPC values <20% of those of the susceptible checks (maximum AUDPC value 2500 on susceptible check) were considered to be slow rusters. In present study, some of the wheat varieties (DBW 93, HS 490, PBW 723, PBW 644, VL 829, VL 892, WH 1105, WR 544 ) grown at present in northern India were identified as slow ruster lines. The information generated can be utilized in improving the stripe rust resistance of popular cultivars.
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.
Stripe rust, is a major constraint to wheat production in the more than 12.8 m ha region of the Northern Hills and North Western Plains zones in India. The previously deployed resistance genes Yr9 and Yr27 are no longer effective. New sources of resistance (Yr5, Yr10, Yr15, Yr24) became available under the umbrella of an Indo-Australian collaborative project. A set of advanced backcross derivative lines out yielded the checks in preliminary evaluations and were promoted to station-level (16 lines) and national (5 lines) trials. A new cohort of resistance genes (Yr47, Yr51, Yr57) are now available and are being used in the breeding program. Resistance genes Yr17, Yr18, Yr31, Yr36, Yr40, Yr53, YrC591, and Yr70 are also being used. The recent progress in development of high yielding, stripe rust resistant lines will help to address future threats from stripe rust.
The flag leaf and spike are the prime organs in wheat (Triticum aestivum L.) which contribute majorly for spike photosynthesis and eventually aid in grain filling. In this study we have tried to elucidate the effect of abiotic stress on the grain filling and spike photosynthesis. In order to unravel the role of flag leaf, awn, and spike in wheat grain filling and spike photosynthesis, 1000-kernel weight were calculated after removing flag leaves, awns, and by shading the spike in four wheat genotypes (PBW343, C306, K7903, HD2329) for two seasons (2014-2015, 2015-2016). A significant decrease in the grain filling was observed for all the genotypes. These results indicate the role of these organs in spike photosynthesis. The role of the awn tissue was investigated in PBW343 for its role in spike photosynthesis during heat stress. Deep transcriptome sequencing of the awn tissue (PBW343) was performed and it revealed 147573 unigenes. Out of these, 394 genes were differentially expressed genes (DEGs). These DEGs constitutes 201 upregulated and 193 downregulated genes. Genes involved in photosynthesis (Ribulose bisphosphate carboxylase/oxygenase activase B, NADH dehydrogenase, Fe-S protein2), membrane integrity (ATP-dependent zinc metalloprotease FTSH6), and ion channel transporters (two-pore potassium channel3) were prominently expressed. Gene Ontology (GO) enrichment analysis represents PSII associated light-harvesting complex II catabolism, chloroplast organization, photosynthesis light harvesting in photosystemI, ethylene biosynthesis, regulation of oxidoreductase activity, stomatal closure, chlorophyll biosynthesis categories, which are highly overrepresented under heat stress conditions. Therefore, utilizing the awn transcriptome information, Rubisco activase (RCA) gene was chosen for overexpression studies in wheat and rice with the aim to enhance the photosynthetic efficiency of the spike tissue leading to higher grain filling.
Wheat crop is attacked by three rust diseases of which stripe rust, caused by Puccinia striiformis f. sp. tritici and leaf rust, caused by Puccinia triticina, are the most common causing greater yield losses. Thirty genotypes were studied for (APR) adult plant resistance and were evaluated in field conditions and controlled conditions. HPW 373, VW 20145, VL 3002, RKVY 231, VL 907, PBW 698 and HS 507 were found to be highly resistant to yellow rust at both seedling and adult plant stages. While, genotypes HS 490, HPW 314, HPW 360, RKVY 133, Raj 4362, DBW 113 and HPW 403 showing very low AUDPC values were found to be moderately resistant under field conditions. These lines are suggested for use in breeding program and some are in network trials for their direct release. Inheritance studies were carried out to decipher the genetics of seedling rust resistance in elite germplasm line HPW 373. The F2s were evaluated for seedling resistance against yellow rust (46S119, 78S84) and leaf rust (77-5-North American equivalent THTTM) races. Resistance in HPW 373 is controlled by single dominant gene against leaf rust (77-5) and stripe rust (78S84). Against stripe rust (46S119), resistance of HPW 373 is controlled by recessive gene. The findings are expected to contribute towards enriching diversity for leaf and stripe rust resistance in bread wheat improvement programmes.
Seed is a basic, vital and central input in agriculture and in all farming systems. Timely availability of quality seeds of varieties/hybrids adapted to to different agro-climatic conditions and in sufficient quantity at affordable prices is a measure of the strength and health of an agricultural economy. Sustained increase in agricultural production requires a continuous development of improved crop varieties/hybrids, an efficient system of production, and a means of distribution to farmers. India is one of the few countries where the seed sector has advanced in parallel with the agricultural production. However, the availability of quality seed of improved varieties and hybrids is grossly inadequate and is a major constraint to enhanced production. Studies made by several workers (Gadwal 2003, Patil et al 2004, Hanchinal et al. 2007) clearly indicate that with high-volume low-value seeds, such as wheat, groundnut, soybean and chickpea, 80% of the cropping area is sown with farm-saved seeds of old and obsolete varieties During last few decades, a number of high yielding disease and pest resistant varieties/hybrids in different crops had 10 to 40% yield superiority over local cultivars. With the exception of high-value low-volume seeds, seed production of low-value high-volume crops is generally left to public sector agencies. The bulky nature of most self pollinated crops, and lack of adequate investment on infrastructure means low remuneration. Although there is enough breeder seed production in most of the high volume crops, further seed multiplication through the foundation and certified seed stages are major constraints to the availability of quality seed. The present rate of seed replacement (SRR) for such crops is 6 to 8%. There is a need to increase SRR to 25 to 30% in varieties and obviously 100% for hybrids. To increase the productivity of low-value high-volume crops farmers need to have access to improved seeds of the right type, at the right time, at the right place and at a reasonable price. For supply of such seeds, both the informal seed sector (farmer managed seed systems) and the formal seed system (seed enterprises) need to be engaged. The informal seed sector is often highly effective in reaching isolated, inaccessible, small holder areas and is a sound opportunity for entrepreneurs to gradually evolve into the formal enterprises Wheat, the most important food crop of world and backbone of global food security, belongs to the highvolume low-value seed group. Of the total area sown to both hexaploid bread wheat and tetraploid durum and emmer wheat worldwide, 44% (95 m ha) is in Asia. Of this,62 m ha are located in just three countries viz. China, India, and Pakistan (Table 1 and Figure 1). Food security and production stability are of paramount importance in most Asian countries, given that the majority of farmers are poor. The wheat rusts have historically been major biotic constraints both in Asia and the rest of the world. Stem rust has been under control since the beginning of the green revolution in South and West Asia in the 1960s. Leaf rust and stripe rust continue to be major threats to production over approximately 60 (63%) and 43 (46%) m ha, respectively, in Asia. Although, the timely application of fungicides can provide adequate control, their use adds to production costs and they are considered environmentally unsafe. Growing resistant cultivars is thus the most effective and efficient control strategy, as it has no cost to farmers and is environmentally safe. Rapid evolution of races with new virulences, or combinations of virulences, dictate a need for discovery and deployment of new resistance genes and/or resistance gene combinations.