Nikolett Réka Aranyi

Changes in the Distribution of European Mistletoe (Viscum album) in Hungary During the Last Hundred Years

The hemiparasitic European mistletoe (Viscum album) from the family Viscaceae (Santalaceae s.l.) is able to infest more than 380 woody taxa in Europe. At the beginning of the 20th century, less than 10 % of Hungary was infested. The distribution area was centralized in the Transdanubian Mountains, and no mass occurrence was noticed elsewhere. Since then, the infested area has almost tripled, and heavily infested forests can be observed in numerous parts of Hungary, especially in the northeast area of the Hungarian Great Plain. However, the central region of the Hungarian Great Plain is still uninfested. In the North Hungarian Mountains, where the presence of potential hosts is very frequent, mistletoe is still quite rare. The most infested macroregion of Hungary is Western Transdanubia, the only region where all three different subspecies can be found. No significant changes have been observed in the proportions of the most common hosts in the last 90 years, with poplars (Populus spp.) and black locust (Robinia pseudoacacia) still being the most frequently infested species. Silver maple (Acer saccharinum) is now a heavily infested host in city parks, while the abundance of infested apple (Malus spp.) and pear (Pyrus spp.) trees has decreased with the transformation of cultivation techniques. In infested areas, nine to twelve of the most common 18 host species can be found, while only five to eight species can be observed in uninfested areas. The increased mistletoe occurrence can be attributed to several factors, including human impact, larger forest area and a growing number of breeding pairs of the mistle thrush (Turdus viscivorus).

Improvement of the agronomic traits of a wheat–barley centric fusion by introgressing the 3HS.3BL translocation into a modern wheat cultivar

The 3HS.3BL spontaneous Robertsonian translocation obtained from the progenies of wheat-barley (Chinese Spring × Betzes) hybrids backcrossed with wheat line Mv9kr1 was transferred into the modern Martonvásár wheat cultivar Mv Bodri. The translocation was identified with molecular cytogenetic methods. The inheritance of the translocation was traced using genomic in situ hybridization. Fluorescence in situ hybridization using barley subtelomeric (HvT01) and centromere-specific [(AGGGAG)4] repetitive DNA probes confirmed that the complete barley chromosome arm was involved in the Robertsonian translocation. The wheat-specific repetitive DNA probes identified the presence of the whole wheat genome, except the short arm of the 3B chromosome. Genotypes homozygous for the centric fusion were selected, after which morphological analysis was performed on the plants and the yield components were measured in the field during two consecutive vegetative seasons. The introgression of the 3HS.3BL translocation into the modern wheat cultivar Mv Bodri significantly reduced the plant height due to the incorporation of the dwarfing allele RhtD1b. The presence of the 3HS.3BL translocation in the Mv9kr1 and Mv Bodri wheat background improved tillering and seeds per plant productivity in field experiments carried out in Martonvásár and Keszthely, Hungary.

What types of powdery mildew can infect wheat-barley introgression lines?

This work is a detailed study of the infection of fungal biotrophic pathogens causing powdery mildew diseases on introgression lines originating from the intergeneric hybridisation between wheat and barley (Triticum aestivum L. × Hordeum vulgare L.). Powdery mildew fungi are among the most widespread biotrophic pathogens of plants also and infect dicot and monocot species. Most powdery mildew species are strictly host specific. They colonize only a narrow range of species or one particular host species. The intergeneric hybridisation between wheat and barley could result in expansions of host ranges of the barley powdery mildew. Our experiments covered natural infections in the field and artificial infections under greenhouse conditions. Formae speciales of powdery mildew were identified on the basis of the sequencing results of ribosomal internal transcribed spacer sequences (rDNA-ITS). We identified Blumeria graminis f.sp. tritici isolate 14 (HM484334) on the wheat parent and all wheat-barley introgression lines and B. g. f. sp. hordei isolate MUMH1723 (AB 273556) on the barley parent, respectively. The wheat-barley introgression lines were inoculated with barley powdery mildew under greenhouse conditions. According to our results the added barley chromosomes (or segments) do not cause host range expansion of barley powdery mildew.