P. Ruckenbauer

Molecular mapping of QTLs for Fusarium head blight resistance in spring wheat. I. Resistance to fungal spread (Type II resistance)

Abstract Fusarium head blight (FHB, scab) is a fungal disease of wheat and other small cereals that is found in both temperate and semi-tropical regions. FHB causes severe yield and quality losses, but the most-serious concern is the possible mycotoxin contamination of cereal food and feed. Breeding for FHB resistance by conventional selection is feasible, but tedious and expensive. This study was conducted to identify and map DNA markers associated with FHB resistance genes in wheat. A population of 364 F1-derived doubled-haploid (DH) lines from the cross ’CM-82036’ (resistant)/’Remus’ (susceptible) was evaluated for Type II resistance (spread within the spike) during 2 years under field conditions. Marker analysis was performed on 239 randomly chosen DH lines. Different marker types were applied, with an emphasis on AFLP and SSR markers. Analysis of variance, as well as simple and composite interval mapping, were applied. Three genomic regions were found significantly associated with FHB resistance. The most-prominent effect was detected on the short arm of chromosome 3B, explaining up to 60% of the phenotypic variance for Type II FHB resistance. A further QTL was located on chromosome 5A and a third one on 1B. The QTL regions on 3B and 5A were tagged with flanking SSR markers, the 1B QTL was found associated with the high-molecular-weight glutenin locus. These results indicate that FHB resistance is under control of a few major QTLs operating together with unknown numbers of minor genes. Marker-assisted selection for these major QTLs involved in FHB resistance appears feasible and should accelerate the development of resistant and agronomically improved wheat cultivars.

Back-cross reciprocal monosomic analysis of Fusarium head blight resistance in wheat (Triticum aestivum L.)

Abstract Fusarium head blight (FHB or scab) caused by Fusarium spp. is a widespread disease of cereals causing yield and quality losses and contaminating cereal products with mycotoxins. The breeding of resistant varieties is the method of choice for controlling the disease. Unfortunately, the genetic basis of scab resistance is still poorly understood. We present the results of a back-cross reciprocal monosomic analysis of FHB resistance using the highly resistant Hungarian winter wheat line ‘U-136.1’ and the highly susceptible cultivar ‘Hobbit-sib’. Resistance testing was performed in a field trial artificially inoculated with a Fusarium culmorum conidial suspension. Five hemizygous families containing ‘U-136.1’ chromosomes 6B, 5A, 6D, 1B, and 4B had a visually reduced spread of infection compared to lines having the ‘Hobbit-sib’ chromosome. Chromosome 2B from ‘U-136.1’ had an increased spread of infection. The critical chromosomes controlling seed weight were 6D, 3B, 5A, and 6B while those controlling deoxynivalenol (DON) content were homoeologous groups 2 and 6, although the latter effects were not significant due to a high coefficient of variation. Results from this and other studies show that chromosomes 6D, 6B, 5A, 4D, and 7A have frequently been associated with scab resistance in a number of wheat cultivars. Research groups now attempting to map scab resistance in wheat using markers should pay special attention to the above-mentioned chromosomes.

Present Strategies in Resistance Breeding Against Scab ( Fusarium Spp .)

Fungi of the group Fusarium spp. have long been recognized as pathogens on many plant species. Wheat and other small grain cereals may be attacked by Fusarium spp. on different plant organs, but the infestation of the ear appears to be most critical, leading to Fusarium head blight (FHB), also known as Fusarium ear blight (FEB), pink mold or scab. The risk of a FHB epidemic is high when natural inoculum is abundant (e.g. conidia or ascospores on crop debris on the soil surface) during warm and humid weather at flowering. Despite the range of species implicated in the disease, Fusarium graminearum (Gibberella zeae), F. culmorum, and F. avenaceum (G. avenacea) appear to predominate worldwide (Parry et al., 1995). Their geographical distribution is related to temperature requirements, with F. graminearum dominating in hotter regions and F. culmorum in cooler regions (Parry et al., 1995). The typical disease symptoms begin with brownish watersoaked spots on glumes and rachis which lead to bleaching of parts of the ears. A salmonpink to red fungal growth may appear along the edge of the glumes or the base of the spikelet. Infected grains shrink and become white, gray or brown, sometimes with pink spots and have a floury discolored interior, known as tombstone kernels. The disease may cause severe losses in grain yield. Arthur (1891) reports a case a where wheat field with a yield expectation of 35–40 bu/ac in fact yielded only 8 bu/ac as a result of the 1890 epidemic. FHB of wheat also causes relevant quality losses by reducing kernel weight and size. Milling and baking quality as well as brewing quality are affected by degrading starch and proteins (Bechtel et al., 1985; Diehl, 1984). Fusarium infected grains have been associated with gushing of beer. A general review of FHB on small grains has been published by Parry et al. (1995).

The effect of inoculation treatment and long-term application of moisture on Fusarium head blight symptoms and deoxynivalenol contamination in wheat grains

Fusarium head blight (FHB) is an important disease of wheat, which can result in the contamination of grains with mycotoxins such as deoxynivalenol (DON). Artificial inoculation of flowering ears with conidial suspensions is widely used to study FHB diseases. Our goal was to compare four inoculation treatments in which a conidial suspension was sprayed on flowering ears and to study the effect of the application of moisture during kernel setting and filling with a mist-irrigation system. Ten wheat genotypes were inoculated with a DON-producing Fusarium culmorum strain. Inoculation treatments varied in time of application of the inoculum (morning or evening) and in the method of controlling humidity during inoculation (bagging or mist irrigation). A wet season was simulated with a mist-irrigation system, keeping the crop canopy wet for at least 26 days after flowering. The severity of FHB symptoms (area under disease progress curve (AUDPC)), yield loss and DON contamination in the grains were determined. AUDPC data obtained with the different inoculation treatments were highly correlated (r=0.85–0.95). Mist irrigation after inoculation resulted in a higher mean disease severity, but in a overall lower toxin contamination as compared to the non-irrigated treatments. Genotypic differences in DON accumulation were present: for one wheat line toxin contamination significantly increased when irrigated, while two genotypes accumulated significantly less toxin. The closest relationships (r=0.73–0.89) between the visual symptoms and the DON content were obtained under moderate mean infection pressure. This relation between visual symptoms and the DON content deteriorated at higher infection levels.

Environmental and genetic variation of soybean seed protein content under Central European growing conditions

Seed protein content is important for both feed and food utilisation of soybean. In soybeans grown in Central Europe, considerable variation in protein content was due to seasonal influences, as demonstrated in different experiments from a breeding programme. In soybean genotypes of early maturity groups, average to high protein content (range 399—476 g kg−1) was found in years with high air temperature and moderate rates of rainfall during the seed-filling period, whereas seed protein content was drastically reduced (range 265–347 g kg−1) in seasons of insufficient nitrogen fixation or higher amounts of precipitation during seed filling. In a set of 60 genotypes, protein content was increased both by late nitrogen fertilisation before the onset of seed filling and by inoculation of seed with nitrogen-fixing rhizobia. Despite the high degree of environmental modification, genetic variation of seed protein content was considerable, and genotype × environment interaction was of low magnitude. Therefore selection of early maturing soybean genotypes with improved seed protein content appears to be feasible and is only limited by the moderately negative correlation between protein content and seed yield. © 2000 Society of Chemical Industry

The effect of fertilization on yield and quality of Miscanthus sinensis ‘Giganteus’

Abstract In Austria it is planned to use Miscanthus sinensis ‘Giganteus’ as a renewable energy source. Therefore, effects of the age of the crop, time of harvest and application of fertilizers on yield, water content and quality of Miscanthus sinensis ‘Giganteus’ were investigated. In February of the second year after planting, yield of Miscanthus sinensis ‘Giganteus’ was 8 t d.m./ha and reached, in the third year of cultivation, 22 t d.m./ha. Yield was highest in September and from that time on, due to senescent leaves, decreased steadily. Different amounts of nitrogen fertilizers had no clear effect on yield because at the beginning of the vegetation period of the second year N min content of the soil was between 145 and 165 kg N/ha and between 190 and 340 kg N/ha in the third year. In September, water content of Miscanthus sinensis ‘Giganteus’ was about 60%. At the end of February, the usual harvest time, of the second year after planting water content was about 42% and in the third year approximately 30%. Nitrogen content of the plants was highest at the beginning of the growing season and decreased thereafter. In February of the second year, nitrogen content was about 6.6 g/kg d.m. followed by 5 g/kg d.m. in the third year. Due to a more intensive nitrogen fertilization water and nitrogen content increased almost linearily within the investigated range of nitrogen fertilization (0–180 kg N/ha) applied. The calorific value of Miscanthus sinensis ‘Giganteus’ was as high as firewood. Finally ash content of Miscanthus exceeded firewood but was determined lower than that of straw.

Stability of quality traits in Austrian-grown winter wheats

Abstract Stability of breadmaking quality of Austrian-grown quality wheats was investigated using rheological parameters from the farinogram (dough development time, stability, degree of softening) and the extensogram (extensibility, maximum resistance, energy), indirect parameters (protein content, wet gluten content, Zeleny sedimentation volume, Hagberg falling number) and the loaf volume. Stability was evaluated for a set of eight cultivars grown in 15 environments in north-eastern Austria. Five stability parameters, covering a wide range of statistical approaches, were used to describe the cultivars. There was variability for stability of quality in the set of cultivars. Some cultivars were stable for one trait and unstable for another, suggesting that the genetic factors involved in genotype by environment interactions differed between traits. It was possible to identify a check cultivar which was stable for almost all quality traits. The absolute performance of the cultivars was considered by calculating the reliability of each cultivar as a safety first index. It is demonstrated that quality wheats of Austrian origin show high performance for all quality traits except for degree of softening and Hagberg falling number.

Germination of 110-year-old cereal and weed seeds, the Vienna Sample of 1877. Verification of effective ultra-dry storage at ambient temperature

After 110 years of hermetic sealed storage at temperatures between 10 and 15°C and at a moisture content of 3.12%, Hordeum vulgare showed 90% germination and Avena sativa 81%. In addition, some seeds of Agrostemma githago, Lolium temulentum, Sinapis alba, Sinapis arvensis , and Vaccaria hispanica were still capable of germinating. This demonstrates that ultra-dry, long-term seed storage under ambient temperature conditions can successfully be achieved with the intention of cutting down risks and costs in germplasm conservation.

A sensitive and inexpensive yeast bioassay for the mycotoxin zearalenone and other compounds with estrogenic activity.

ABSTRACT Zearalenone (ZON) is a nonsteroidal estrogenic mycotoxin produced by plant-pathogenic species of Fusarium. As a consequence of infection with Fusarium culmorum and Fusarium graminearum, ZON can be found in cereals and derived food products. Since ZON is suspected to be a cause of human disease, including premature puberty syndrome, as well as hyperestrogenism in farm animals, several countries have established monitoring programs and guidelines for ZON levels in grain intended for human consumption and animal feed. We developed a low-cost method for monitoring ZON contamination in grain based on a sensitive yeast bioassay. The indicator Saccharomyces cerevisiae strain YZRM7 is unable to grow unless an engineered pyrimidine biosynthetic gene is activated by the expressed human estrogen receptor in the presence of exogenous estrogenic substances. Deletion of the genes encoding ATP-binding cassette (ABC) transporters Pdr5p and Snq2p increases net ZON uptake synergistically. Less than 1 μg of ZON per liter of medium is sufficient to allow growth of the indicator strain. To prevent interference with pyrimidines potentially present in biological samples, we also disrupted the genes FUR1 and URK1, blocking the pyrimidine salvage pathway. The bioassay strain YZRM7 allows qualitative detection and quantification of total estrogenic activity in cereal extracts without requiring further cleanup steps. Its high sensitivity makes this assay suitable for low-cost monitoring of contamination of maize and small grain cereals with estrogenic Fusarium mycotxins.

Screening techniques and sources of tolerance to salinity and mineral nutrient imbalances in cool season food legumes

A large global land area is affected by saline, alkali (sodic), and acid soil conditions. Cool season food legumes are important crops in many countries with such adverse soils. Tolerant genotypes have been identified in many crops, including legumes. However, very little has been published on selection of tolerant cool season food legume crops. The inadequate knowledge and understanding of the responses of cool season food legume crops to these abiotic stresses, necessitates action by a collaborative network of interdisciplinary teams to make rapid progress in identifying tolerant germplasm and developing cultivars better adapted to unfavorable soil conditions.