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Oomycetes are water molds that are frequently isolated during a survey of waterways. Biodiversity of oomycetes in the estuary region of the Veleka River in Bulgaria was investigated in 2021. A total number of 32 isolates were derived using the baiting method. Species identification based on sequencing of the ITS region divided them into four different genera: Phytophthora (P.), Phytopythium (Pp.), Pythium (Py.) and Elongisporangium (E.). The most abundant species in the studied region was P. lacustris (sixteen isolates), followed by P. honggalleglyana (nine isolates). P. bilorbang and P. inundata were represented by only one isolate each and were recognized for the first time in Bulgaria. The genus Phytopythium was presented by two isolates that belong to different species, Pp. litorale and Pp. citrinum. In the obtained collection, the genera Pythium and Elongisporangium were represented by only one species each, Py. angustatum (one isolate) and E. anandrum (two isolates), respectively. Colony morphology of the eight collected oomycete species was characterized by cultivation of selected isolates on three different media. Potential host species of the isolated estuarine oomycetes were estimated by pathogenicity tests conducted with sixteen plants from ten diverse families. P. lacustris and P. honggalleglyana demonstrated a higher aggressiveness among Phytophthora isolates, whereas P. bilorbang and P. inundata showed less ability to infect the tested plant species. Similar pathogenicity and a potential host range for both Phytopythium species were observed. Less aggressive against analyzed plants in this study were Py. angustatum and E. anandrum. [ABSTRACT FROM AUTHOR]

A number of Phytophthora species have been identified as destructive plant pathogens and invasive species. They have the potential to affect a wide range of host plants and cause diseases in agricultural and forest ecosystems. Two Phytophthora species from rhizosphere soil samples collected from declining Alnus glutinosa in Bulgaria were isolated in the autumn of 2022. They were identified as Phytophthora polonica and Phytophthora hydropathica according to the DNA sequence analysis of the ITS region, as well as their morphological and physiological characteristics. The pathogenicity of both species to common and gray alder was evaluated by the inoculation of detached leaves and cuttings. Experimental data proved that P. polonica and P. hydropathica are able to cause leaf necrosis not only on A. glutinosa from which they were derived, but also on A. incana. No significant deference in the aggressiveness of the studied isolates from both Phytophthora species against the two tested plants was observed. Therefore, P. polonica and P. hydropathica were determined as potential threats for alder ecosystems in the country. This is the first report for the isolation of P. polonica in Bulgaria and represents the most southeastern point of the species distribution in Europe. [ABSTRACT FROM AUTHOR]

A novel cold-inducible GSK3/shaggy-like kinase, TaSK5, was isolated from winter wheat using a macroarray-based differential screening approach. TaSK5 showed high similarity to Arabidopsis subgroup I GSK3/shaggy-like kinases ASK-alpha, AtSK-gamma and ASK-epsilon. RNA gel blot analyses revealed TaSK5 induction by cold and NaCl treatments and to a lesser extent by drought treatment. TaSK5 functionally complemented the cold- and salt-sensitive phenotypes of a yeast GSK3/shaggy-like kinase mutant, △ mck1 . Transgenic Arabidopsis plants overexpressing TaSK5 cDNA showed enhanced tolerance to salt and drought stresses. By contrast, the tolerance of the transgenic plants to freezing stress was not altered. Microarray analysis revealed that a number of abiotic stress-inducible genes were constitutively induced in the transgenic Arabidopsis plants, suggesting that TaSK5 may function in a novel signal transduction pathway that appears to be unrelated to DREB1/CBF regulon and may involve crosstalk between abiotic and hormonal signals. [ABSTRACT FROM AUTHOR]

Two Phytophthora pseudosyringae isolates were recovered from aquatic ecosystems in Bulgaria during a two‐year investigation of Phytophthora distribution in water sources in the country. Isolate RVit2016/6d was derived from Boyana Lake at the Vitosha Mountain, whereas isolate RTr2016/32d was obtained from Erma River at the Ruy Mountain. Both isolates belong to P. pseudosyringae species according to their morphological and physiological characteristics, as well as to the DNA sequence analysis of the internal transcribed spacer (ITS) region. The pathogenicity of the isolates to wild cranberry plants (Vaccinium vitis‐idea) was studied by detached leaves experiments and in planta. Both P. pseudosyringae isolates were able to cause leaf necrosis and death of plants within 3 months. The ability of the pathogens to infect cranberry leaves at different temperatures was also investigated. The significance of P. pseudosyringae species and its potential threat for forest ecosystems is discussed. To our knowledge, this is the first report of P. pseudosyringae isolation in Bulgaria. [ABSTRACT FROM AUTHOR]