Displaying 1 - 5 of 5
The Cereal Crops Research Institute (CCRI) is situated on the left bank of River Kabul, near village Pirsabak, 3 km east of Nowshera at an elevation of 288 m above sea level on the intersection of 74? E longitude and 32? N latitude. In July 2010, a devastating flood destroyed all the available germplasm, machineries, laboratories, and field equipment. After the flood research activities were restarted with full motivation, dedication and hard work in collaboration with PARC, ICARDA, CIMMYT, and with the help of wheat productivity enhancement program (WPEP). Developed new population of wheat via spring x spring, spring x facultative germplasm to elevate genetic diversity and lines selected from segregating populations for high yield and rust resistance are at advanced stage of testing.
Since the flood, the CCRI developed four new wheat cultivars: Pirsabak-2013 Pakhtunkhwa-2015 for irrigated areas and Shahkar-2013 and Pirsabak-2015 for rainfed areas of Khyber Pakhtunkhwa, Pakistan. Varietal maintenance and seed production of the released varieties has been undertaken by the wheat breeding team effectively. The seed of these newly developed wheat cultivars was multiplied on fast track basis through pre-released seed multiplication and now these four varieties are the most popular cultivars of Khyber Pakhtunkhwa, Pakistan. Three new candidate wheat lines (PR-106, PR-110 and PR-112) have been submitted to provincial seed council for approval as new wheat cultivars for Khyber Pakhtunkhwa, Pakistan. Two new candidate lines i.e. PR-115 and PR-118 got first position in National Uniform Wheat Yield Trials (NUWYT) on the basis of grain yield during 2016-17 under irrigated and rainfed conditions, respectively.
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.
Short season, high latitude spring wheat is grown on 7 million ha in Western Siberia and 10 million ha in Northern Kazakhstan. Despite relatively low wheat yields (1.5 t/ha), the region is extremely important for regional and global food security. Leaf rust dominates, occurring three years out of five, especially in favorable years with higher rainfall. Since 2010, stem rust has been observed at an increasing number of sites. The first large-scale stem rust outbreak occurred in 2015 and affected about 0.5-1 million ha in Omsk, Western Siberia. In 2016, 2 million ha were affected in the Omsk and Altay regions, while 1 million ha in the Kostanay and Northern Kazakhstan regions were affected in 2017. Estimated yield losses reached 25-35% each year. Factors associated with the outbreaks included: higher rainfall in late June and July; cultivation of susceptible varieties; and an increased area planted to winter wheat, which serves as a source of inoculum. Sampling and race analysis revealed a diverse pathogen population, indicative of a sexual recombination. A total of 51 races were identified from 31 samples taken in 2015 and 2016. All races were avirulent on Sr31. The majority of varieties released and cultivated in the region are susceptible to stem rust and require replacing. A recent study of 150 local resistant varieties and breeding lines indicated that the genetic basis of resistance was limited to Sr25, Sr31, Sr36, Sr6Ai, Sr6Ai#2, and additional unknown major genes. Adult-plant resistance to stem rust was observed in less than 20% of the germplasm. The potential impact of these large stem rust outbreaks on other wheat growing regions is being investigated by analyzing spore wind dispersal patterns. Further research is required to understand and mitigate the sudden appearance of stem rust as a disease of economic importance.
Study at Omsk State Agrarian University was supported by the Russian Science Foundation (project No. 16-16-10005).
Northern Kazakhstan and Western Siberia are major high latitude spring wheat growing regions on the Eurasian continent. Rust epidemics can cause serious crop losses in this region. For this purpose, the Kazakhstan-Siberian network for wheat improvement (KASIB) was created in 2000. Seventy wheat cultivars and lines from a KASIB nursery were characterized for seedling and adult plant resistance (APR) to leaf rust using Australian pathotypes in greenhouse and field experiments. A molecular marker (STS iag95) detecting 1RS and therefore genes located in the rye component of the 1BL.1RS translocation was used to verify the presence/absence of Lr26. Field assessments of the nursery were conducted at Cobbitty using mixed Pt pathotypes. Lr26 was detected in five cultivars (Bayterek, GVK-1916-9, Altayskaya 105, Ok-1, and Omskaya 36) based on seedling tests using seven pathotypes. This was confirmed using the SRS marker. Other genes postulated included Lr3a (in cv. GVK 1860/8, GVK 1369/2, GVK 1857/9, and GVK 1526-2) and uncharacterized gene/s in cv. Zhenis and Lutescens-166 SP 94). The majority of KASIB entries were susceptible in seedling tests to Pt, but varying levels of potentially useful resistance were observed in 23 genotypes tested in the field. Low infection types on seedlings and field resistance in cv. Tertsia, Aria, and Sonata suggested the presence of unknown gene/s of potential value that warrant further investigation. Future efforts to breed wheat varieties resistant to one or more of the cereal rust pathogens will require identification of resistance sources that differ from those already present. Understanding the dynamics of pathogenic variability in pathogen populations is also important in selecting appropriate resistances.
Wild relatives, landraces and cultivars from different geographical regions are demonstrated sources of resistance to wheat rusts. Identification, characterisation and provision of diverse sources of rust resistance to Australian wheat breeding companies form a key component of the Australian Cereal Rust Control Program. This study was planned to assess diversity of resistance to the three rusts among a set of Nordic spring wheat cultivars. These cultivars were tested at the seedling stage with several pathotypes of each rust pathogen. Stem rust resistance genes Sr7b, Sr8a, Sr12, Sr15, Sr17, Sr23 and Sr30 and leaf rust resistance genes Lr1, Lr3a, Lr13, Lr14a, Lr16 and Lr20 were postulated either singly or in various combinations. A high proportion of cultivars were identified to carry Sr15/Lr20 presumably due to earlier selection, or fixation, of Pm1 in breeding populations. Seedling test data using five Pst pathotypes did not allow postulation of genes present in a many cultivars because of a widely effective single gene or overlapping effectiveness of two or more resistance genes. Stripe rust resistance gene Yr27 was postulated in five cultivars. The presence of Yr1 in one cultivar was predicted by amplification of the linked marker allele. Eighteen, 47 and 32 cultivars showing seedling susceptibility, respectively, to stem rust, leaf rust and stripe rust were tested under field conditions to identify sources of adult plant resistance (APR). Cultivars possessing APR to all three or to two rusts were identified. Molecular markers linked to APR genes Lr34/Yr18/Sr57, Lr68, and Sr2 detected the likely presence of these genes in some cultivars.