Comparative Genetic Analysis of Fhb-resistant Germplasm for Wheat Improvement

Fusarium head blight (FHB) is one of the most destructive diseases of wheat. Repeated screening of genetic resources has led to the identification of several resistant cultivars of spring wheat, such as Frontana from Brazil, Sumai 3 from China and Nobeokabouzu-komugi from Japan. It is known, however, that several morphological and ecological variations with different responses to FHB exist within global accessions of Frontana and Sumai 3 (Nishio et al. 2002), and different sources of Sumai 3 have been identified by DNA markers (Bai et al. 2003). In this study, we revealed the genetic variation within accessions of Frontana (Brazil, USA, Canada and Japan) and Sumai 3 (China, USA, Canada, Iran, Austria and Japan) that had been sent to CIMMYT by using 242 SSR markers that encompass the whole wheat genome. FrontanaUSA and -CAN were identical with, or variants of, the original Brazilian accession. In the case of Sumai 3, the US, Canadian and Iranian accessions were the same genotype as the Chinese one. Sumai 3-JIR might be a derivative from them. The Austrian accession was considered a derivative of an original Chinese accession following outcrossing and selection with additional resistance genes for FHB. The results of genetic variation within the accessions of Frontana and Sumai 3 reveal that we need to pay attention to the source and genotype of such accessions when discussing the results of QTL analysis and using them in breeding programs with marker assisted selection. (This poster was presented at the 10th International Wheat Genetic Symposium, Paestum, Italy, 1-6 September 2003.) 2003 National Fusarium Head Blight Forum Proceedings 219 Germplasm Introduction and Enhancement IMPORTANCE OF FUSARIUM HEAD BLIGHT IN RUSSIA AND THE SEARCH FOR NEW SOURCES OF GENETIC RESISTANCE IN WHEAT AND BARLEY T. Yu Gagkaeva Dept. of Mycology and Phytopathology, All-Russian Institute of Plant Protection (VIZR), St.-Petersburg Pushkin, Podbelski str., 3 Russia, 196608 Corresponding Author: PH: (812) 470-51-10; E-mail: [email protected] Russia is large country occupying over 17 million km2 and very diverse climatic conditions. Cereal crops are cultivated in the European (North Caucasus, the Central and Volga regions, North-Western region) and Asian regions (Siberia and the Far East) of the country. Wheat and barley are significant components of the agricultural economy of Russia. Winter and spring wheat are grown on over 23-25 million hectares with an average annual production of 30.9-50.6 million tons (average for 1999-2002). Winter and spring barley are grown on 9.8-10.3 million hectares with an average yield of 10.9-19.5 million tons. The first mention of Fusarium head blight (FHB) within the territory of Russia was from the Far East. The Far East region of cereal production is typically very damp and warm during the summer due to the influences of Sea of Japan and Pacific Ocean. As early as the 18th century, FHB was known as a problem of cereals in the Far East (Palchevsky, 1891; Voronin, 1890). From 1882 until about 1914, FHB epidemics occurred almost every year in the region. The use of seeds and straw contaminated with mycotoxins produced by various Fusarium species caused numerous cases of food poisoning in people and animals. Initially, the symptoms observed in people ingesting this tainted grain resembled alcohol intoxication and was often referred to as “intoxicating bread” syndrome. The research of several Russian mycologists revealed that the fungus Gibberella saubinetii Sacc. (now G. zeae or F. graminearum) was the principal causal organism of FHB (Jaczewski, 1904; Naumov, 1913, 1916). FHB was a persistent problem in the Far East during the first half of the 20th century (Abramov, 1938; Naumov, 1940) and continues to be today. High severities of FHB are reported nearly every year in the region. Mycological analyses of seed samples from 1998-2002 have shown a high level of FHB-infected wheat and barley seed (from 23-32%). The most frequently isolated pathogens were F. graminearum, F. avenaceum, and F. poae. Another major FHB outbreak within the territory of Russia occurred in the Altai region and Bashkirij (south of Siberia) in 1932-1945. Food shortages during this time forced rural people to consume inferior grain that was left out in the field under snow during the winter. After ingesting this grain, many people suffered the serious disease of alimentary toxic aleukia. Extensive research led by A. Sarkisov revealed that the disease was due to the ingestion of cereals contaminated with T-2 toxin produced by fungus F. sporotrichioides (Sarkisov, 1954). In recent years, the level of Fusarium infected grains has been relatively low (0-10%). The principal pathogens found on grain in this region are F. poae and F. sporotrichioides (Levitin et al., 2000). Nearly one hundred years after the first major epidemic was reported in the Russian Far East, FHB became one of the most important fungal diseases in the North Caucasus region. There, FHB epidemics occurred in 1985, 1987, 1988, 1992, 1993, 1997, 1998, 2000, and 2002. In the North Caucasus, maize and winter wheat and winter barley are the main crops and are often cultivated in continuous rotation with each other. Favorable weather conditions, coupled intensive agricultural practices have led to a dramatic increase in 2003 National Fusarium Head Blight Forum Proceedings 220 Germplasm Introduction and Enhancement FHB severity. Since cereals in the North Caucasus comprise nearly one third of the total cereal production in Russia, the severity of FHB epidemics was of great concern and research efforts to combat the disease were initiated. F. graminearum (G. zeae) is the most important FHB pathogen in this region and was responsible for widespread mycotoxin contamination problems. For example, in 1992, analysis of wheat grain from the Krasnodar district showed that DON was present in 100% of the examined samples with concentrations ranging from 0.15-10.5 ppm. In 57% of samples, the level of DON exceeded the permissible level for human consumption (1 ppm). Zearalenone was observed in 68% of the samples in concentrations ranging from 0.01-1.4 ppm (Lvova et al., 1997). The NorthWest region (near Baltik Sea) is characterized by a damp climate and moderate summer daytime temperatures. In past years, FHB was reported on cereal crops in the region, but was never considered a significant problem (Naumov, 1940). A study of seed infection from recent years revealed significant levels of FHB. In 2000, FHB seed infection averaged 16% (maxiumum 23%) and 22% (maxiumum 24%) for spring barley and spring wheat, respectively. In 2002, the average FHB infection level for both barley and wheat seed was about 6% with a maximum of 15%. The 2003 season was very wet and all harvested grain was infected by FHB. The average level of grain infection by Fusarium species was 16% for barley (maximum 32%) and 12% for wheat (maximum 20%). The dominant species isolated from seed were F. poae, F. sporotrichioides, F. avenaceum. In this area, symptomatic kernels are rarely observed, except in warm and moist seasons like in 2003. More often asymptomatic kernels are found to carry infections of various Fusarium species. Analyses of trichothecene toxins conducted with Finnish colleagues in 2002 revealed principal toxin in this region is nivalenol (0,2-3.7ppm), most likely produced by F. poae (YliMattila et al. 2002). Disease resistance is one of the best means of combating FHB in wheat and barley. In the past, the breeding programs for cereals in the Central, North-West regions, and Siberia never focused on FHB resistance. This led to the release of many susceptible cultivars, which were planted over a large area. In Russia, the most active breeding program focusing on FHB resistance is at the Krasnodar Research Institute of Agriculture (North-Caucasus). This is an area of winter cereal production and recently released winter wheat cultivars such as Krsnodarskaya 6, Yuna, Delta, Demetra, Kolos, Leda, Rufa, Eho, Basianka appear to have tolerance to toxin accumulation (Anpilogova et al., 1996; Ablova, Gritcai, 2001; Kolesnikov et al., 2001; Ribalkin et al., 2000). To breed for FHB resistance, breeders are making crosses among ecogeographically diverse lines and making early generation selections of individuals. Successive crosses are complex involving highly resistant in Krasnodar region Nung Ta 173 (China), Lee (USA), Frontana (Brazil), WSP96.6, Livius (Austria), Kincso, Ringo Sztar (Hungary) and local varieties (Ribalkin et al., 2000). To broaden resistance to FHB, efforts are being made to identify new resistance sources. The N. I. Vavilov Institute of Plant Industry (VIR) in Russia houses one of the largest and most diverse collections of cereal genetic resources in the world. The wheat collection contains more than 44,000 accessions. Approximately two-thirds of the collected accessions (27,832) include bread wheat germplasm originating from 85 countries. Wild and primitive wheat accessions number 2,867 and goat grass (Aegilops L.) accessions number 3,847. A considerable part of the wheat collection was obtained from 1907 to 1940 and are mostly landraces or old varieties. The barley collection comprises 20,197 accessions of cultivated barley: 39% are landraces, 46% are cultivars, 8% are breeding lines, 6% are mutants and genetic stocks and 1% is wild species. In 1947, the number of accessions in the collection amounted to 9000, representing 38 countries besides Western Europe (Kovaleva, 1999; Mitrofanova, 2003; Terenteva, 2001). Estimation of the degree of biodiversity for disease resistance in the genetic resources of cultivated plants and their wild relatives is being documented in joint projects between VIR and VIZR. 2003 National Fusarium Head Blight Forum Proceedings 221 Germplasm Introduction and Enhancement Evaluation of wheat and barley accessions from VIR collection identified a group of landraces and old local cultivars of wheat and barley with relatively high levels of FHB resistance (Gagkaeva et al., 2002). All these samples were collected from 1915-1936 in the Far East territory where environmental conditions are favorable for FHB infection. Two hundred fifty-two accessions comprising 26 species of Triticum L. with different ploidy levels were evaluated for FHB resistance in the field. No correlation was found between ploidy level and FHB resistance. However, some feature of plants may be associated with resistance. For example T. durum, T. aethiopicum, and T. turanicum have a high frequency of florets that undergo open flowering and are susceptible to FHB. Likewise, T. urartu has a prolonged flowering period and is susceptible to FHB. T. timopheevii, T. persicum, T. ispahanicum, and T. karamyschevii originated from regions with high moisture and were generally resistance to FHB. T. vavilovii, T.turanicum, T. dicoccoides, T. sphaerococcum originated from dry regions of Middle Asia and were highly susceptible to FHB. The most resistant wild accessions were T. timopheevii, T. karamyschevii, and T .militinae (from Georgia), T. persicum (from Dagestan), T. dicoccum (from Germany), T. spelta (from Switzerland). A wide diversity for resistance was detected in T. aestivum accessions (Gagkaeva et al., 1993) Aegilops species are of particular interest because they carry genes for resistance to many fungal pathogens that may be introgressed into common wheat. Aegilops accessions belonging to 9 different species and several ploidy levels (Ae.tauschii, Ae.triuncialis, Ae.cylindrica, Ae.juvenalis, Ae.vavilovii, Ae.ovata, Ae.crassa, Ae.kotchui, Ae.bicornis) were evaluated for reaction to FHB. Ae. tauschii was most resistant to F. graminearum. Of 56 samples belonging to this species 19.6% were highly resistant. All tested samples of Ae. triuncialis and Ae. ovata were highly susceptible (Gagkaeva, Navruzbekov, 1991). The most of resistant Ae. tauschii germplasn originated from Afghanistan. One of them is used in crossing with wheat at the Crop Breeding Institute (Harbin, China) (Lianfa et al., 2000). The wild accessions (T. militinae, Ae. squarosa, Ae. sharonensis, Ae. umbellulata, Ae. speltoides, Ae. glaucum, S. cereale) are potential sources of resistance to the disease and toxin accumulation and are being utilized for breeding purposes at the Krasnodar Research Institute of Agriculture (Kolesnikov et al., 2001). The combining of different resistance genes from diverse sources will broaden the effectiveness of FHB resistance in released cultivars.