AWN Vol 41

ITEMS FROM AUSTRIA

University of Agriculture - Vienna

Institute of Agronomy and Plant Breeding, Gregor Mendel Str. 33, A-1180 Vienna, Austria, and the Institute for Agrobiotechnology, Department of Plant Science, Konrad Lorenz Str. 20, A-3430 Tulln, Austria.

Fusarium head blight on wheat.

H. Buerstmayr, M. Lemmens, H. Grausgruber, F. Moule, M. Fidesser, and P. Ruckenbauer.

Investigations on Fusarium head blight (FHB, scab) resistance in wheat have continued in 1994. Natural outbreaks of FHB are rare in Austria, but plant breeders and grain marketing organizations are increasingly aware of the disease, particularly because of the danger of mycotoxin contamination and quality losses.

Research activities on Fusarium head blight focus on the following topics:

1) Improvement of artificial inoculation techniques. The severity of Fusarium spp. attack on wheat spikes depends on the developmental stage of the plants, the presence and nature of inoculum, and the environmental conditions, in addition to plant resistance.

In a resistance-breeding program, plant resistance has to be measured as accurately as possible. Therefore, in the case of artificial inoculation, other influences must be controlled very carefully. The control of the developmental stage of the plants and inoculum is rather easy - inoculation takes place during anthesis. The inoculum used is a spore suspension of a Fusarium isolate with known pathogenicity and a defined concentration. More difficulties arise with environmental conditions, e.g., temperature and humidity. In field trials, temperature cannot be controlled. Control of humidity is possible in several ways: 1) inoculate in the evening, 2) keep humidity high by covering inoculated ears with plastic bags, and 3) maintain high humidity with a mist-irrigation system.

To compare the above-mentioned ways of humidity control, a field trial was carried out in 1994. A set of 25 winter wheat genotypes of known resistance was sown in two replicates and inoculated with two Fusarium isolates. Disease development was measured by visual scoring over a period of 26 days after inoculation and, for each entry, an area under the disease progressing curve (AUDPC) was calculated. The methods were compared for repeatability and accuracy. The results have shown that the use of a mist-irrigation system for humidity control was superior to other methods.

We thank the Austrian National Bank for their financial support, Project number 4906.

2) Resistance breeding. To support the private Austrian plant breeders, we gave them F2 bulks of 100 reciprocal crosses between FHB-resistant winter wheats and well adapted Austrian wheat cultivars.

The following table shows the parents used in the crosses. Most of the lines have been tested for FHB resistance during 3 years under artificial inoculation. Disease development was assessed by visual scoring over a period of 26 days after inoculation and, for each entry, the AUDPC was calculated.

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FHB 1992 FHB 1993 FHB 1994

Line Origin (AUDPC) (AUDPC) (AUDPC)

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UNG 226 Hungary 3.07 1.34 9.70

SVP 72017-17-5-10-1 The Netherlands 17.70 2.45 6.91

81 F3 79 France 15.71 1.36 6.79

Arina Switzerland 20.39 2.70 6.68

UNG 171 (Bence) Hungary 17.14 3.16 11.07

UNG 159 Hungary 38.25 0.82 8.85

Praag 8 Czech Republic 23.03 1.76 5.72

Novokrumka 0102 Russia 21.29 1.05 9.88

SVP C8718-5 The Netherlands 7.18 0.86 8.29

UNG 136.1 Hungary 0.58 0.64 7.15

Leopold Austria - 6.69 11.40

Aurus Austria 48.58 19.18 18.40

Perlo Austria 11.23 5.25 8.10

Capo Austria 25.07 5.64 8.10

Bimbo Germany 34.33 8.21 15.65

Alidos Germany - 14.57 -

Martin Austria 12.01 2.10 8.59

Justus Austria 23.92 5.68 12.85

Ikarus Austria 42.65 7.35 10.70

Hubertus Austria 36.55 7.88 20.60

Agron Austria 7.03 4.25 21.70

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We thank the Ministry of Agriculture and Forestry for financial support, Project number L687/91.

3) Germplasm screening. A number of winter and spring wheat genotypes, foreign germplasms, and Austrian genotypes have been evaluated for FHB resistance. No complete resistance was found, but considerable genetic variation was detected. Spring durums tend to be most susceptible. Some Chinese Spring wheat lines are most resistant.

4) Studies on the genetic basis of FHB resistance. A backcross, reciprocal monosomic analysis was done with the monosomics of the very susceptible cultivar, Hobbit-sib, from IPSR Norwich, England. The Hobbit-sib monosomics were crossed with two resistant wheat lines from CRI Szeged, Hungary. The resistant Hungarian lines have resistance from Nobeokabozu-komugi and/or Sumai #3 in their pedigree.

In addition, existing single chromosome substitution lines, which we obtained from Mr. A.J. Worland (IPSR Norwich), were investigated. The analysis of substitution lines included the Hobbit-sib (Triticum macha), Chinese Spring (Cheyenne), Chinese Spring (Triticum spelta), Chinese Spring (Hope), and Chinese Spring (Lutescens) substitution series. Fusarium head blight was induced by artificial inoculation with Fusarium graminearum and F. culmorum isolates. Visual scoring of diseased spikelets was done over a period of 26 days after inoculation, and the AUDPC calculated. Furthermore, the harvest reduction of diseased ears was determined.

The results of the 1994 data of the Hobbit-sib (Triticum macha) substitution line indicate possible resistance genes on chromosomes II (2A), IX (5A), and X (6B), estimated for AUDPC. QTLs for FHB resistance may be located on these chromosomes.

Markers for FHB resistance would be of great value for resistance breeding. The development of test stocks for the identification of markers is underway.

5) In vitro selection for FHB resistance. In order to decrease the amount of artificial field inoculation required in a FHB resistance breeding program, a study was carried out to develop a simple laboratory method to predict FHB resistance of wheat. In the literature, several methods are described to select plants with increased level of disease resistance using the toxic metabolites produced by the fungus as selection agents. Fusarium spp. produce several toxins on wheat, the most important of which are the trichothecenes (e.g., deoxynivalenol (DON)). These toxins probably play a role in the aggressiveness of the pathogen and promote disease development and colonization. They inhibit eukaryotic protein synthesis by blocking the peptidyl transferase step. It has been reported that plants tolerant to these toxins have an increased resistance to FHB. In this study, the germination of seeds from 25 winter wheat genotypes was examined in the presence of Fusarium toxins. Germination of seeds requires abundant protein synthesis. The results were compared with accurate data of the field resistance of the above-mentioned wheat nursery to FHB.

Fusarium graminearum isolates were grown on maize agar (containing maize powder, 75 g/l; agar, 10 g/l) and incubated in the dark at 25 C for 6 to 8 weeks. Toxin analyses (Dr. Mesterhazy, Szeged, Hungary) showed that the DON content varied from less than 1 to 18.5 ppm. Toxic Fusarium medium (TFM) was diluted 1:2, 1:5, and 1:10 (w:w), and buffered at pH 6.5 with phosphate buffer. Agar was added to a final amount of 6 g/l. The media were autoclaved and poured into Petri dishes (15 cm diameter). One hundred disinfected seeds were put horizontally, with the embryo directed upwards, on the agar and slightly pressed into the medium. Water agar (pH 6.5) was used as a control. The dishes were incubated in the dark at 5 C. The cumulative number of germinated seeds was counted daily. The data were plotted against days after imbibition and were fitted to a Gompertz function. The number of germinated seeds in TFM was calculated when the control medium contained 80 germinated seeds (NGTC80).

Germination was retarded in TFM. Significant differences were found in toxicity of the TFM and in tolerance of the genotypes. Correlation coefficients between data of NGTC80 and field resistance data ranged from 0.60 to 0.75. The TFM also contained other toxins (e.g., zearalenon). Whether DON alone or in combination with other toxic Fusarium agent(s) in the TFM is responsible for the selective toxic effect is currently under investigation.

We greatly acknowledge the financial support by the Austrian Science Foundation (FWF), Project number P09190-BIO.

Publication.

van Eeuwijk FA, Mesterhazy A, Kling CI, Ruckenbauer P, Saur L, Buerstmayr H, Lemmens M, Keizer LCP, Maurin N, and Snijders CHA. 1994. Assessing non-specificity of resistance of wheat to head blight caused by inoculation with European strains of Fusarium culmorum, F. graminearum, and F. nivale using a multiplicative model for interaction. Theor Appl Genet (In press).

Breeding for bread making quality of wheat using protein electrophoresis.

S. Greger, H. Bistrich, B. Charvat, and T. Lelley.

In a research project financially supported by the Austrian Science Foundation (P10300-CH), crosses between Austrian and Hungarian wheat breeding lines and cultivars have been made. Using the DH and SSD techniques, recombinant inbreed lines are being produced representing specific combinations between different HMW-glutenin, LMW-glutenin, and gliadin alleles. These lines will be investigated for their qualitative and their quantitative protein combinations and for different baking quality parameters. The relationship between the occurrence of certain proteins and the bread making quality will be analysed. Because some of the Hungarian lines used as crossing parents contain the 1BL-1RS translocation, we also want to analyse the effect of the translocation on quality.

We investigated 91 Austrian and 72 Hungarian winter wheat varieties and breeding lines, which were tested in the respective national trials in 1992 for their high molecular weight (HMW) glutenin subunits and for the presence or absence of the 1BL-1RS translocation using SDS-PAGE. In the Austrian material, 19 different allele compositions were found; in the Hungarian material, 18 different allele compositions were found. In the Austrian and Hungarian material, the prevailing allele compositions were 0, 7Y+9, 5+10 (28.6 %) and 2*, 7Y+9, 5+10 (31.5 %), respectively. Two Hungarian varieties were found to contain a new Glu-B1 allele, 14+19, which seems to be a recombination between the alleles 13+19 and 14+15. We also detected differences in the mobility of the HMW glutenin subunit 7 in several varieties. The 1BL-1RS translocation occurred in only 11.5 % of the Austrian, but in 51 % of the Hungarian material. The Austrian variety Ferdinand was found to contain a complete 1B/1R substitution. Significant correlations between the presence of different HMW glutenin subunits and the Zeleny sedimentation volume were detected. The highest positive correlations were found with the subunits 2*, 7Y+9, and 5+10, and the highest negative correlation with 2+12.

Producing wheat double haploids using `wheat x maize' hybridisation.

S. Greger, Ch. Bitsch, B. Charvat, and T. Lelley.

For our studies concerning bread making quality in wheat, we introduced the method of `wheat x maize' hybridisation to produce wheat DHs. We received an average number of 3.7 embryos/ear and 3 green haploid plants/ear. During this work, different techniques to make the method more practical and less time consuming are being tested; e.g., for the colchicine treatment, after excision the embryos will be put on a medium containing colchicine for 1 day. Thereafter, the embryos will be replanted on a colchicine-free medium.

We are also investigating the effect of the 1BL-1RS translocation and the 1B/1R substitution on the efficiency of haploid production, by the above method, using near isogenic lines. The first experiments have been done to produce DHs from triticale through hybridisation with maize.

Introducing bread making quality into triticale.

J. Lafferty and T. Lelley.

To improve bread making quality of triticale, chromosome 1D, with HMW glutenin subunits 5+10, is being introduced into different improved hexaploid triticale genotypes. This chromosome substitution was possible after the production of 1D/1A, 1D/1B, and 1D/1R chromosomal substitution lines in hexaploid triticale (Kazman E and Lelley T. 1994. Plant Breed 113:89-98). The procedure first involved the production of primary octoploid triticale, using hexaploid wheats with high bread-making quality having the HMW glutenin subunits 5+10 in the Glu-D1 locus. These

octoploid triticales then were crossed with selected hexaploid triticale varieties. In this winter season, we successfully backcrossed the pentaploid F1 with their respective triticale varieties. Seeds produced through backcrosses will be tested with SDS-PAGE for the presence of the 5+10 subunits. Plants showing these subunits will be backcrossed again to their respective triticale parents. After another backcross, isogenic lines, with or without substitution of chromosome 1D for its respective homoeologous group one chromosome, will be selected and tested for bread making quality.