Stress-induced memory alters growth of clonal offspring of white clover (Trifolium repens).

PREMISE OF THE STUDY: The phenotype of an individual can be modified by the environment experienced by its predecessors, a phenomenon called transgenerational or maternal effects. These effects are studied mostly across sexual generations and are thought to be mediated also by epigenetic variation. However, we do not know how important transgenerational effects are across asexual generations of clonal plants. METHODS: We investigated the role of different drought intensities and durations experienced by parental plants of Trifolium repens on the growth of offspring ramets after transplantation of clonal cuttings to control conditions. We also treated half of the plants with 5-azacytidine, which is a demethylating agent, to test the potential role of DNA methylation on transgenerational effects. KEY RESULTS: Transgenerational effects were manifested as increased biomass of offspring ramets if parental plants experienced medium drought applied for a short period and decreased biomass of offspring ramets if parental plants experienced intense drought for a short period. These transgenerational effects were not observed for offspring of parents from the same treatments if these were treated with 5-azacytidine, whose application significantly decreased the amount of 5-methyl-2'-deoxycytidine in plants. CONCLUSIONS: Transgenerational effects might play an important role in the clonal plant Trifolium repens and are probably mediated by epigenetic variation. The growth and behavior of clonal plants might be affected not only by the ambient environment but also by environments that are no longer present at the time of clonal reproduction. This phenomenon can have yet unacknowledged ecological and evolutionary implications for clonal plants.

Common bunt in organic wheat: unravelling infection characteristics relevant for resistance breeding.

Common bunt caused by Tilletia tritici and T. laevis has re-emerged as a major threat to wheat yield and quality, especially in organic farming. Resistance against its causal agents is present in the wheat gene pool and provides the most economically efficient and sustainable way to combat the disease since seed treatments approved for organic farming are rare and do not always provide full protection. We tested a winter wheat diversity panel with 128 lines for common bunt resistance in Austria and Czechia, and evaluated the applicability of marker-assisted selection (MAS) via Kompetitive Allele-Specific PCR markers in genotypes with high variation in their genetic background. Field trials were conducted across two years and artificially inoculated with local bunt populations. The virulence patterns of these inocula differed between locations and only 15% of the tested genotypes showed stable resistance across test sites. Number and weight of bunt sori relative to the total number and weight of wheat grains in sampled ears revealed that partial infections of ears were frequently appearing. Forty-two breeding lines harboring combinations of four different resistance QTL were developed through MAS. Out of these, a quarter were resistant with a maximum of 5% common bunt incidence. On the other hand, only six out of 46 tested commercial cultivars and breeding lines showed no infection with common bunt, underlining the present scarcity of bunt-resistant cultivars for organic wheat production. By this study we showed that MAS is a useful tool to speed up the selection of resistant lines even in populations with highly diverse genetic backgrounds, and that it is efficient in pyramiding resistance loci and thereby improving the level of resistance.

The Use of Real-Time PCR for the Pathogen Quantification in Breeding Winter Wheat Varieties Resistant to Eyespot.

The reaction of twenty-five winter wheat cultivars frequently grown in the Czech Republic to inoculation with Oculimacula yallundae and Oculimacula acuformis was evaluated in small plot trials from 2019 to 2021. The eyespot infection assessment was carried out visually using symptoms on stem bases and quantitative real-time polymerase chain reaction (qPCR). The cultivars were also tested for the presence of the resistance gene Pch1 using the STS marker Xorw1. Statistical differences were found between cultivars and between years. The lowest mean level of eyespot infection (2019-2021) was visually observed in cultivar Annie, which possessed resistance gene Pch1, and in cultivar Julie. Cultivars Turandot and RGT Sacramento were the most susceptible to eyespot. The method qPCR was able to distinguish two eyespot pathogens. O. yallundae was detected in higher concentrations in inoculated plants compared with O. acuformis. The relationship between the eyespot symptoms and the pathogen's DNA content in plant tissues followed a moderate linear regression only in 2021. The highest eyespot infection rate was in 2020 due to weather conditions suitable for the development of the disease.