Tibor Kiss

Due to global climate change, short periods of unusually warm temperatures occur during winter and early spring with increasing frequency. Although temperature effects on wheat development have been extensively studied during later reproductive stages, the consequences of short-term warming during early development remain poorly understood. We investigated the effect of a short-term period of warm temperature on partially or fully vernalized wheat seedlings, with particular attention to their phenological characteristics and grain-yield formation. A total of 19 wheat varieties of diverse geographic origins were studied with known allele compositions in plant developmental genes of vernalization (VRN) and photoperiodic response (PPD). The experiment consisted of six treatments in factorial combinations of three low-temperature vernalizations (30, 45 and 60 days) followed by two temperature regimes (greenhouse and two-week 25 °C plus greenhouse) under long photoperiod. The effects of transient warming were strongly dependent on the degree of vernalization fulfilment. In fully vernalized winter wheat, warming generally accelerated development across genotypes, whereas after incomplete vernalization, it frequently delayed subsequent developmental transitions, particularly in photoperiod-sensitive cultivars. Variation in responses increased with decreasing vernalization saturation, indicating that allelic differences at flowering-time loci, including VRN and PPD, contribute to the integration of temperature signals during early development. Beyond phenology, transient warming strongly influenced tiller formation and reproductive tiller number. Following complete vernalization, warming increased fertile tiller production and resulted in higher grain yield, whereas responses after partial vernalization were genotype-dependent and less favorable. Comparison with previous controlled-environment experiments further demonstrated that thermal regime, rather than mean temperature alone, strongly influences tiller survival and yield formation. Short-term warming around the completion of vernalization can have long-lasting effects on wheat development and productivity, highlighting the importance of developmental stage, genetic background and environmental context in determining crop responses to increasingly variable winter temperatures.

As the frequency of droughts increases, the breeding of new drought-tolerant cereal varieties may become increasingly important. However, the complex effects of drought stress on grain yield-related traits are difficult to study precisely, and relatively little information is available on how drought during flowering affects plants. Therefore, 28 winter barley cultivars were included into controlled environmental tests, where their reactions were determined to single drought stress treatment applied at heading and to combined drought stresses applied at first node appearance and then at heading. Drought stress (both single and combined) significantly reduced all of the grain-yield related traits. Notably, grain yield was reduced by 48% in the two-row varieties and by 44.24% in the six-row varieties under combined drought stress, compared to the control. Our study has also demonstrated, that the combined application of drought tolerance/susceptibility indices (DT/SIs) and BLUP-based analysis provides a reliable approach for identifying stress-tolerant genotypes. We identified two main types of drought stress tolerance: the ability of preserving grain number and weight in the main ears, in parallel of maintaining the number of reproductive tillers (more tolerant), and the ability of preserving grain number and weight in the side ears (least tolerant). Both types appeared in either treatment, but not with the same intensity. Our results may provide useful information for a better understanding of this topic, which may become even more important in the context of increasingly frequent droughts.

The best known Microdochium spp. are important pathogens of small-grain cereals and/or endophytes of diverse monocot hosts. This study is the first report of M. majus isolated from asymptomatic grapevine tissues. It was hypothesised that this M. majus strain, CBS 152328, was an endophyte and an antagonist of some fungal pathogens of grapevine. Microscopic examinations revealed that this strain was a necrotrophic mycoparasite of Botrytis cinerea. This was demonstrated in the confrontation zones of dual cultures of M. majus and B. cinerea, and also on the surface of co-inoculated grape leaf discs and germinated wheat grains. Pathogenicity tests indicated that M. majus can colonise both grape leaf discs and germinated wheat, but it only damaged wheat. When co-inoculated with B. cinerea onto grape leaf discs, the M. majus strain CBS 152328 suppressed its mycohost on grape tissues and prevented leaf necrosis caused by B. cinerea. In addition to the parasitism, M. majus also showed mild antibiosis against B. cinerea, as well as a defence elicitor effect on grape leaf discs. This work is the first report of the mycoparasitic behaviour of M. majus, in addition to its first isolation from a dicot host.

Background: High-quality RNA extraction from woody plants is difficult because of the presence of polysaccharides and polyphenolics that bind or co-precipitate with the RNA. The CTAB (cetyl trimethylammonium bromide) based method is widely used for the isolation of nucleic acids from polysaccharide-rich plants. Despite the widespread use of the CTAB method, it is necessary to adapt it to particular plant species, tissues and organs. Here we described a simple and generalized method for RNA isolation from mature leaf tissues of several economically important woody (17) and herbaceous plants (2) rich in secondary metabolites. High yields were achieved from small amount (up to 50 mg) of plant material. Two main modifications were applied to the basic protocol: an increase in β-mercaptoethanol concentration (to 10%v/v) and the use of an effective DNase treatment. As opposed to similar studies, we tried to describe a more detailed protocol for isolating RNA, including the exact quantity and concentration of the reagents were used. Results: Our modified CTAB method is proved to be efficient in extracting the total RNA from a broad range of woody and herbaceous species. The RNA yield was ranged from 2.37 to 91.33 µg/µl. The A₂₆₀:A₂₈₀ and A₂₆₀:A₂₃₀ absorbance ratios were measured from 1.77 to 2.13 and from 1.81 to 2.22. The RIN value (RNA Integrity Number) of the samples fell between 7.1 and 8.1, which indicated that a small degree of RNA degradation occurred during extraction. The presence of a single peak in the melt curve analyses and low standard errors of the Ct values of replicated measurements indicated the specificity of the primers to bind to the cDNA. Conclusions: Our RNA isolation method, with fine-tuned and detailed instructions, can produce high quality RNA from a small amount of starting plant material that is suitable for use in downstream transcriptional analyses. The use of an increased concentration of the reducing agent β-mercaptoethanol in the extraction buffer, as well as the application of DNaseI-treatment resulted in a method suitable for a wide range of plants without the need of further optimalization, especially in Rhus typhina (Staghorn sumac), for which molecular-genetic studies have not yet been sufficiently explored.