Many of the catalogued leaf rust resistance genes in wheat deployed in agriculture have been overcome by variants of Puccinia triticina (Pt), the causal pathogen of leaf rust. Discovery and characterization of new sources of resistance in various germplasms using multipathotype tests and molecular markers could permit future diversification of the genetic base of leaf rust resistance in wheat. In searching for new sources of leaf rust resistance, 140 wheat lines from 14 African countries were tested with 8 Australian Pt pathotypes. Seedling tests revealed that 41% of the lines were susceptible to all pathotypes, 31% were postulated to carry either one of 10 resistance genes (Lr1, Lr2a, Lr3a, Lr13, Lr18, Lr23, Lr24, Lr26, Lr37 or Lr73) or one of five gene combinations (Lr2a+Lr3a, Lr1+Lr13, Lr1+Lr23, Lr1+Lr13+Lr73 and Lr23+Lr73). Twenty-eight percent of the lines were postulated to carry uncharacterized seedling resistance genes. Based on average coefficients of infection (ACI), 101, 25 and 11 lines showed high (ACI 0-19), moderate (ACI 21-38) and low (ACI 41-56) levels adult plant resistance, respectively, whereas three lines were moderately susceptible to susceptible (ACI 63-76). Genotyping of 74-78 lines that were anticipated to carry APR genes, using the molecular markers: csLV34 (linked to Lr34) and KASP SNP markers SNP1G22 and SNPT10 (linked to Lr46 and Lr67), respectively, revealed the presence of Lr34, Lr46 and Lr67 in 11, 22 and 14 wheat lines, respectively. The identities of the APR in the remaining 22 lines are unknown, and potentially represent new resistance sources. Genetic analyses of these uncharacterized APR sources are underway to select single gene lines and allow fine mapping.
Primary Author: Kankwatsa, The University of Sydney, Plant Breeding Institute, Australia
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.
Primary Author: Kanwal, Wheat Research Institute, Ayub Agricultural Research Institute,Faisalabad,Pakistan
Stem rust (SR) resistance is required for CIMMYT durum germplasm to keep relevance in Ethiopia, where Ug99 and other Pgt races are a major yield-limiting constraint, and in countries along the possible dissemination paths of these races. Resistance to Ug99 is widespread in most durum germplasm groups when tested in Kenya, but resistance is lost when exposed to Ethiopian races; hence selection at the Debre Zeit site in Ethiopia is essential for durum wheat. Due to difficulties with shuttling segregating populations between Mexico and Ethiopia, we have adopted a strategy involving the identification of resistant/moderately resistant lines at Debre- Zeit, and inter-crossing in Mexico followed by selection for resistance to leaf rust and agronomic type and finally screening for SR reaction in the resulting F6 lines at Debre-Zeit at the same time as they are tested for yield and quality in preliminary yield trials in Mexico. This has generated a significant increase in the proportion of resistant and moderately resistant genotypes within outgoing CIMMYT germplasm, from less than 3% at the onset of the initiative in 2008 to 16% in 2011, and 38% in 2013. SR-resistant germplasm was characterized by similar frequency distributions to other traits in the overall germplasm such as yield potential, drought tolerance and industrial quality parameters. Advances have also been realized using marker-assisted selection (MAS) to introgress Sr22 from bread wheat and to combine it with Sr25, producing advanced lines with 2-gene stacks with confirmed outstanding resistance and superior quality attributes. Since the two genes are closely linked but from different sources bringing them together required a very rare recombination event finally detected via MAS among thousands of plants. They are now essentially inherited together with a very low likelihood of generating recombinant individuals with either gene. The yield potential and stability of these lines are under evaluation in Ethiopia and the best lines are being used in a second round of breeding.
Primary Author: Karim Ammar, CIMMYT
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.
Primary Author: Karkee, Nepal Agricultural Research Council, National Agriculture Genetic Resources Centre, Khumaltar, Lalitpur
Wheat yellow rust, caused by Puccinia triticina f. sp. tritici, is the major problem in wheat production in most parts of West Asia. Monitoring of the pathogen virulence factors and their changes provides basic information for the development of an early warning system. Wheat yellow rust has become increasingly important in the Syrian central and coastal areas during the last three years, The objective of this study was to identify races of the pathogen. Yellow rust samples collected at sites in the central and the coastal plains, were analyzed on differential host genotypes with known seedling resistance genes. According to the results of race determination, races 230E150, 166E150, 230E142 and 462E128 were identified. The race 462E128 designated the Warrior race, was identified at several sites across the Syrian central plains at the end of the 2017 growing season (early and Mid-May) when yellow rust exploded suddenly on a number of varieties, despite their previous high resistance ratings. The infections rapidly reached significant levels, in spite of the high temperature (up to 33?C) and the absence of rainfall or irrigation. This new virulent race (462E128) has been able to attack wheat lines with several major resistance gene(s) including: Spaldings Prolific (SP), Yr 3+4, Triticum spelta (Yr5), which remained effective until 2016 in Syria, Virulence to lthe resistance genes Yr1, Yr2, Yr2+, Yr3V, Yr3ND, Yr4+, Yr6, Yr6+, Yr7, Yr7+, Yr9, Yr9+, Yr11, Yr12, Yr18, Yr24, Yr26 Spaldings Prolific (YrSP), Anza (YrA+) Spaldings Prolific (SP), Yr 3+4, Triticum spelta (Yr5) and Selkirk (YrSK) was also found. Virulence to Carstens V (CV), Yr 15/6* Avocet S and Yr 5/6* Avocet S; was not found. According to our findings, the Warrior race has increased in frequency within the mix of yellow rust races in these areas in Syria . It is expected that the Warrior yellow rust race will cause damage on resistant wheat cultivars in 2018.
Primary Author: Kassem, Aleppo University, Aleppo , Syria
While Africa is home to three Berberis species (B. holstii, B. hispanica and B. vulgaris), genera of the family Berberidaceae do not occur naturally in South Africa. However, due to the trade in ornamental plants, a total of 11 Berberis species, 11 cultivars and 8 hybrids were historically and/or are currently cultivated in the country. The current invasive status of most of these species is unknown, but two naturalized Berberis populations were recently discovered. B. julianae was found in the Golden Gate Highlands National Park in eastern Free State province, and B. aristata was found in the Woodbush Forest Reserve in Limpopo province. Since several Berberis species could act as alternate hosts for Puccinia graminis and P. striiformis, a phylogenetic study was conducted to identify both naturalized species, as well as several cultivated specimens. One of the cultivated specimens was identified as B. vulgaris, a species well known for its susceptibility to P. graminis. Knowledge gained from this study will be used to intensify the search for more naturalized Berberis populations, as well as to assess the potential threat to wheat cultivation in the country.
Primary Author: Keet, University of Stellenbosch, South Africa
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.
Primary Author: Khan, Sher-e-kashmir University of Agricultural Sciences and Technology of Kashmir, Jammu and kashmir, India
Stripe rust is one of the major limiting factors in wheat production. An objective-based breeding program was initiated at Barani Agricultural Research Station (BARS), Kohat in 2013/14 to transfer APR genes from CIMMYT and ICARDA spring wheat lines into wheat germplasm well adapted in Khyber Pakhtunkhwa (KPK). Nine high yielding but stripe rust susceptible KPK wheat varieties were crossed in various combination with 17 CIMMYT and ICARDA wheat lines carrying resistance genes. The resultant 79 F1s were backcrossed with respective susceptible parents followed by single plant selection in F2 generation. During 2015/16, 367 segregating populations/lines were screened in multi-environment stripe rust tests within Khyber Pakhtunkhwa. Sixty-nine out of 367 lines showing adequate resistance were again screened for strip rust resistance at hot spot and in yield trial at BARS, Kohat during 2016/17. Seventeen lines showed considerable resistance and were higher yielding than check cultivars. Lines exhibiting adequate resistance will be further tested in advanced yield trial at provincial and national level for possible release of new varieties in wheat.
Primary Author: Khan, Barani Agricultural Research Station, Kohat
The experience of seed system development works in Nepal shows that lack of business orientation is one of the key challenges for the growth of Nepalese seed enterprises (SEs). We implemented a business mentorship activity focusing on SEs in the project - Cereal System Initiative for South Asia. The business mentoring (BM) was implemented covering 10 SEs during 2014 to 2017 using discovery sensitization and facilitation mode. The key actions were, SWOT analysis, mentorship to develop strategic business plan, technical facilitation for seed quality improvement through maintenance breeding and on-farm farmer participatory trials as well as large plot demonstrations of recently released and pre-released wheat varieties. This resulted in 45% average increase in the volume of seed sold by individual SEs in three years. Five SEs started maintenance breeding in wheat and by third year, over 50% of the seed sold by the enterprises consisted of newly released varieties compared to 20% before mentoring. The improved performance of SEs prompted seed quality control authority of Nepal to issue a license to two of these private seed companies for maintenance breeding cum foundation seed production. As a consequence, foundation seed production of these entities increased by 60% in three years, and two of them have also started maintenance breeding in rice from 2017. The facilitation in developing business plan by SEs helped them to attract financial resources from different sources in upgrading seed processing, storage and laboratory facilities. Moreover, the National Wheat Research Program of Nepal has proposed the release of a new wheat variety BL 4341 through integration of on-farm trials and seed production data of these SEs. This new variety is resistant to major diseases, yields 7% higher than the popular cultivar NL 297 which was released 32 years ago and needed replacement due to susceptibility to wheat rusts
Primary Author: Khanal, CIMMYT International, South Asia, Regional Office, Kathmandu
In this project to obtain resistant wheat breeding lines/cultivars to stem rust disease, new cultivars and lines of the north breeding program were evaluated in greenhouse with races collected in 2014 from northern regions of Iran, Moghan and Gorgan. Artificial inoculation in greenhouse indicated none of the races had virulence on Sr11, Sr13, Sr24, Sr25, Sr26, Sr27, Sr29, Sr31, Sr32, Sr33, Sr37, Sr39, Sr40, and SrTmp. In order to evaluate seedling resistance, 143 wheat cultivars and new lines under greenhouse conditions were inoculated with four isolates of stem rust in four separate experiments in a randomized complete block design with three replications. Evaluation of the northern germplasm under greenhouse conditions showed that some of the genotypes were resistant against all four isolates. The resistance of some of these new lines was also confirmed in Kenya. Regarding other desirable agronomic characteristics, some of these lines will be introduced as new cultivars in the northern region of Iran.
Primary Author: Khodarahmi, Seed and Plant Improvement Institute, Agricultural Research, Education and Extension Organization (AREEO), Karaj, Iran