Oseva Pro (Czechia)

Quality parameters (glucosinolate content, oil and fatty acid composition) of white mustard seeds and leaves were evaluated. The total glucosinolate content in the mustard seeds was higher than that in the leaves, and sinalbine was found to be the main glucosinolate in both cases. Analysis of the fatty acid content of the oil showed that erucic acid was predominant in the older genetic sources, while the new white mustard varieties contained less erucic acid. The results obtained showed that Fourier transform near-infrared spectroscopy can be used for routine evaluation of samples and for pre-screening purposes in white mustard breeding programmes.

Silvertop is a serious disease of grasses, and severe infestations cause a great deal of damage every year (particularly to seed producers). Inflorescences of infected plants dry prematurely and are sterile. The genera Festuca, Poa, Agrostis, Trisetum, and Cynosurus are the most frequent hosts of this disease, which has newly been reported in a loloid-type intergeneric Festulolium hybrid. The disease was also observed in the genus Lolium, with only rare previous description. The suspicion that Fusarium poae is the causal agent of severe silvertop was confirmed, and the pathogen was morphologically described and confirmed by molecular analysis. The meadow plant bug (Leptopterna dolabrata) may be a vector transferring the pathogen to plants, although a direct pathogen transfer was not demonstrated. Grass colonisation by the pathogen therefore apparently occurs after plant tissues injury by sucking of the meadow plant bug.

The resistance of 59 varieties and three ecotypes of perennial ryegrass (Lolium perenne) to crown rust (Puccinia coronata) and stem rust (Puccinia graminis subsp. graminicola) was evaluated under field and greenhouse conditions at the Grassland Research Station in Zubri in 2011 – 2012. The infection pressure of crown rust was higher in 2011 and most of the investigated accessions, with exception of the variety Charger II, showed high susceptibility in the field. The occurrence of stem rust was low in both years. Artificial inoculation of young plants with urediospores of P. graminis subsp. graminicola in the greenhouse revealed high resistance in the varieties Kokomo and Score.

A set of 15 Italian (Lolium multiflorum), three hybrid (L. boucheanum) and 33 perennial ryegrass (L. perenne) cultivars were evaluated for their rust susceptibility in the field. The cultivars were grown in 2001, 2004 and 2007 at 29, 32 and 27 European sites, respectively. Rust incidence was scored during different growth cycles using a scale from one (no rust) to nine (susceptible). Crown rust (Puccinia coronata f. sp. lolii) was the most frequently observed rust species on Italian, hybrid and perennial ryegrass during all three experimental years. There was a highly significant difference in mean crown rust scores among Italian and perennial ryegrass cultivars, respectively, in each of the 3 years. The ranking of the cultivars was very consistent across the different sites within each year (with some exceptions), despite a significant interaction of cultivar response with sites. Moreover, the rank order correlations of mean cultivar rust scores were highly significant (r > 0.9) between the years. Stem rust (P. graminis f. sp. graminicola) occurred almost exclusively on perennial ryegrass. The cultivars showed significant variation in stem rust susceptibility. Rank order correlations of mean cultivar stem rust scores were mostly significant between sites within each year and highly significant between the years. The ranking of perennial ryegrass cultivars was different depending on whether crown or stem rust was scored. However, the rank order correlation between the mean disease scores of the cultivars for the two pathogens was low but still significant. At a particular site the assessment of crown or stem rust was in most cases very consistent over the period of experimentation. Therefore there was no evidence that rust resistance of an individual cultivar was overcome by the rust pathogen at a particular site over the 7 years of experimentation.

Genebank accessions stored as seed populations require periodic rejuvenation in order to maintain sufficient numbers of viable seeds. During rejuvenation the genetic composition of accessions may be altered for a variety of reasons, of which variation in pollination rates between plants is the least understood. In the present study, a paternity exclusion analysis was performed on a rejuvenated accession of perennial ryegrass. In addition, flowering data of the 49 parental plants were collected during the flowering season. The aim of the study was to determine how accurate variation in pollination rates between plants can be predicted from data on the spatial and temporal distribution of pollen release. The parental population and a total of 551 offspring from 12 progeny arrays were genotyped by means of molecular analysis. Using 25 microsatellites, paternity was identified for 81.9% of the offspring, while remaining ambiguities were resolved by AFLP analysis, except in four cases. Within the total sample 9 cases of contamination were observed. Mating within the study population was clearly non-random, as 61.9% of the identified pollen donors were located within 1 m distance from the mother plant. Observed pollination rates were very well described by an inverse quadratic function of inter-plant distance between potential mating pairs. Incorporation of the recorded flowering data in the calculation of expected pollination rates improved the goodness of fit with observed values by only 0.77%. Suggestions to reduce the variance in paternal contributions were presented. However, contamination was considered more threatening to the genetic integrity of perennial ryegrass germplasm than variation in pollination rates between plants, and indicated the need for improved measures to avoid gene flow from other germplasm.

Doubled haploid (DH) self-incompatible (SI) regenerants with improved seed quality were derived after two improvement crossing cycles with different “00” quality donors. The original genetic resource of recessive sporophytic SI was characterised by a high glucosinolate (GSL) and erucic acid content. SI regenerants of satisfactory seed quality parameters were obtained from the second cycle of crossing. Total number of derived SI plants was 87, i.e. 38.2% out of 228 obtained fertile doubled haploid regenerants developed in 2004. Nine plants out of the analysed 45 SI DH regenerants had the erucic acid content lower than 2%. Five out of these nine plants, which were analysed by HPLC method, had the glucosinolate content lower than the limit 18 µmol/g at 9% seed moisture. The method based on the spraying of inflorescences with 5% NaCl to enable reproduction of SI lines was verified.