Witold Irzykowski

Expression of KS-type dehydrins is primarily regulated by factors related to organ type and leaf developmental stage during vegetative growth

The expression of a gene, designated as DHN10, was analyzed at the protein level in two Solanum species. The DHN10 protein displays some consensus amino acid sequences of dehydrins, termed K- and S-segments. Unlike most dehydrins, both segments occur only in single copies in the DHN10 sequence and the S-segment is at a C-terminal position. Database searches revealed that KS-type dehydrins constitute a specific subclass distributed in dicotyledons and monocotyledons. In Solanum tuberosum L. plants, a high DHN10 abundance was observed under control conditions, particularly in flowers, stems, tubers and young developing leaves. In other Solanaceae and in barley (Hordeum vulgare L.), the amount of DHN10 was much more elevated in young leaves than in old leaves. DHN10 abundance was investigated in two Solanum species subjected to low temperature or to drought. Under stress conditions, we observed substantially higher protein levels only in mature expanded leaves. These findings clearly indicate that KS-type dehydrins are present at a high level in the absence of stress during vegetative growth and that their expression is primarily regulated by factors related to organ type and to leaf development stage. A potential role for the DHN10 dehydrin during plant development and in tolerance to environmental stress is discussed.

Identification and expression of novel cold induced genes in potato (Solanum sogarandinum)

Twelve cold induced cDNA clones have been isolated by differential screening of a cDNA library prepared with mRNA from cold resistant potato (Solanum sogarandinum). Accumulation of mRNA corresponding to each of the clones was analyzed by Northern blot hybridization. The isolated cDNA clones were named Ssci (S. sogarandinum cold induced). All of the clones clearly respond to cold and accumulation of the corresponding transcripts was observed after one day of cold hardening, however, they varied with regard to the timing of mRNA accumulation. Maximum accumulation of mRNA corresponding to the clones Ssci1, Ssci2, Ssci6 and Ssci8 was observed at the first day of cold hardening, while for the clones Ssci3, Ssci4, Ssci5, Ssci7, Ssci9, Ssci10, Ssci11 and Ssci12 after 8 days. Partial DNA sequence was determined from the 5′ and 3′ ends of the clones and was examined for homology with sequences in database. The results showed that the isolated cDNA clones correspond to known genes in the database. They encode mRNAs for the following proteins; mRNA for two different S-adenosyl-l-methionine decarboxylases (Ssci1 and 2), two chloroplasts chaperonins (Ssci3, Ssci4), a cell division cycle protein CDC48 (Ssci5), malate dehydrogenase (Ssci6), myo-Inositol-1-phosphate synthase (Ssci7), protoporphyrin IX: Mg chelatase (Ssci8), elongation factor EF-1α (Ssci9), chloroplast translation elongation factor EF-G (Ssci10), ribosomal L3 protein (Ssci11), and mRNA for TAS14 protein, an ABA inducible protein in tomato. The identified genes may be involved in two different functions referring to cold resistance. One group may protect chloroplasts and cell functions under the stress, while the other may be involved in metabolic adjustment to cold.

Isolation and expression of cold specific genes in potato (Solanum sogarandinum)

The expression of genes corresponding to twenty four cDNA clones (Ssci) representing cold induced mRNAs was examined by Northern blot hybridization in potato plantlets treated with cold, NaCl, sorbitol, water and ABA and is illustrated by data representative of the four expression patterns. The response of the genes to cold was examined in two genetically related potato species: a cold tolerant acclimating Solanum sogarandinum and a cold sensitive cultivated Solanum tuberosum, cv. Cisa. The results of Northern blots revealed that only genes corresponding to four of the analyzed clones (Ssci1, Ssci12, Ssci17 and Ssci20) showed much higher levels of accumulation of the corresponding transcripts during cold treatment in the cold resistant potato as compared with the cold sensitive one. On the other hand, a few other clones (Ssci3, Ssci4, Ssci6, Ssci13, Ssci21 and Ssci29) showed higher levels of the transcripts accumulation in the cold sensitive potato. The remaining 14 clones showed similar levels of the accumulation of the corresponding transcripts under cold in both potato types. With the exception of Ssci12, the clones were not induced by ABA, NaCl, sorbitol or water treatments. There were no differences in the levels of the corresponding transcripts between the control plantlets and those treated with ABA, NaCl, sorbitol and water. The expression of the clones was not regulated in the day/night cycle; however, the Ssci1 and Ssci2 clones, encoding two different S-adenosyl-l-methionine decarboxylases (SAMDC), were up-regulated at night. The level of induction of the Ssci12 clone, encoding the TAS14 protein (dehydrin), was much higher following treatments with ABA, NaCl and sorbitol than with cold and the gene does not respond to water stress. Higher activity of the genes corresponding to the Ssci1, Ssci12, Ssci17 and Ssci20 clones during cold hardening in the cold resistant potato suggests that their expression is associated with the development of freezing resistance. Among them, the genes corresponding to the Ssci17 and Ssci20 clones are cold acclimating specific ones (cas).

Genetic and molecular variability of aTurnip mosaic virus population from horseradish (Cochlearia armoracia L.)

Variability and genetic structure of a novelTurnip mosaic virus (TuMV) population from horseradish (Cochlearia armoracia L.) were examined. Over 60 horseradish plants were tested to identify a total of 28 TuMV isolates, constituting theCochleariaAR moracia (CAR) TuMV population. Two subgroups of the CAR TuMV isolates could be distinguished: subgroup N did not infect oilseed rape (Brassica napus var.oleifera) cv. Westar plants, while subgroup A infected these plants systemically. Two types of infection of oilseed rape plants were induced by inoculation with the CAR TuMV isolates: systemic mosaic infection and systemic necrotic lesions. The complete sequences of isolates CAR37 (subgroup N) and CAR37A (subgroup A) were determined and compared. The sequences ofHC-Pro andCP genes of CAR37 and CAR37A and other isolates of TuMV from other countries were compared to provide some insight into their relatedness. CAR37A, initially regarded as a variant, proved to be very different from CAR37. Re-sequencing after repeated passages confirmed the genetic stability of both isolates.

Biological control of winter wheat pathogens with the use of antagonistic Sphingomonas bacteria under greenhouse conditions

This paper describes, for the first time, the effect of bacteria of the genus Sphingomonas on healthiness of winter wheat. The effect of the application of Sphingomonas cell suspension on development of disease symptoms of powdery mildew and Fusarium head blight (FHB) of winter wheat cv. Bogatka was studied under greenhouse conditions. The abundance of populations of yeast and fungi producing mycelium as well as bacteria of the genus Azotobacter and pseudomonads was determined on wheat kernels. The biocontrol agent reduced the population size of Fusarium poae, and it contributed to better grain filling. The tested Sphingomonas isolate reduced the severity of flag leaf infection caused by pathogenic biotroph Blumeria graminis f. sp. tritici.

Agrochemicals: Effect on genetic resistance in yeasts colonizing winter wheat kernels

Crop protection agents are widely used in modern agriculture and exert direct effects on non-target microorganisms such as yeasts. Yeasts abundantly colonize wheat grain and affect its chemical composition. They can also limit pathogen growth. This study evaluated the sensitivity of yeast communities colonizing winter wheat kernels to benzimidazole, strobilurin, triazole and morpholine fungicides, trinexapac-ethyl, a commercial mixture of o-nitrophenol+p-nitrophenol+5-nitroguaiacol, and chitosan applied during the growing season of winter wheat and in vitro in a diffusion test. A molecular identification analysis of yeasts isolated from winter wheat kernels was performed, and nucleotide polymorphisms in the CYTb gene (G143A) conferring resistance to strobilurin fungicides in yeast cells were identified. The size of yeast communities increased during grain storage, and the total counts of endophytic yeasts were significantly (85%) reduced following intensive fungicide treatment (fenpropimorph, a commercial mixture of pyraclostrobin, epoxiconazole and thiophanate-methyl). This study demonstrated that agrochemical residues in wheat grain can drive selection of yeast communities for reduced sensitivity to xenobiotics. A mutation in the CYTb gene (G143A) was observed in all analyzed isolates of the following azoxystrobin-resistant species: Aureobasidium pullulans, Debaryomyces hansenii, Candida albicans and C. sake. Agrochemicals tested in vitro were divided into four classes of toxicity to yeasts: (1) tebuconazole and a commercial mixture of flusilazole and carbendazim - most toxic to yeasts; (2) fenpropimorph and a commercial mixture of pyraclostrobin and epoxyconazole; (3) propiconazole, chitosan, thiophanate-methyl and a commercial mixture of o-nitrophenol, p-nitrophenol and 5-nitroguaiacol; (4) trinexapac-ethyl and azoxystrobin - least toxic to yeasts. It was found that agrochemicals can have an adverse effect on yeast abundance and the composition of yeast communities, mostly due to differences in fungicide resistance between yeast species, including the clinically significant C. albicans.

Identification of Quantitative Trait Loci Conditioning the Main Biomass Yield Components and Resistance to Melampsora spp. in Salix viminalis × Salix schwerinii Hybrids

The biomass of Salix viminalis is the most highly valued source of green energy, followed by S. schwerinii, S. dasyclados and other species. Significant variability in productivity and leaf rust resistance are noted both within and among willow species, which creates new opportunities for improving willow yield parameters through selection of desirable recombinants supported with molecular markers. The aim of this study was to identify quantitative trait loci (QTLs) linked with biomass yield-related traits and the resistance/susceptibility of Salix mapping population to leaf rust. The experimental material comprised a mapping population developed based on S. viminalis × S. schwerinii hybrids. Phenotyping was performed on plants grown in a field experiment that had a balanced incomplete block design with 10 replications. Based on a genetic map, 11 QTLs were identified for plant height, 9 for shoot diameter, 3 for number of shoots and 11 for resistance/susceptibility to leaf rust. The QTLs identified in our study explained 3%–16% of variability in the analyzed traits. Our findings make significant contributions to the development of willow breeding programs and research into shrubby willow crops grown for energy.

Avirulence genes and mating types in the populations of Leptosphaeria maculans collected from infected oilseed rape plants in Poland in autumn 2010Geny awirulencji i typy kojarzeniowe w populacjach Leptosphaeria maculans zebranych z porażonych roślin rzepaku w Polsce jesienią 2010 roku

The fungi Leptosphaeria maculans and L. biglobosa cause stem canker – one of the most damaging diseases of oilseed rape in Poland and worldwide. The aim of this study was to characterize the composition of avirulence genes and mating types present in current populations of L. maculans in Poland. The study was done in autumn 2010. The isolates of L. maculans (254) were obtained from infected winter rapeseed leaves collected at six locations. DNA (deoxyribonucleic acid) of each isolate was extracted using a CTAB (cetyltrimethyl ammonium bromide) method. The taxonomic identity of isolates was checked by RAPD (random amplification of polymorphic DNA) using OPJ-10 primer and compared with specific banding patterns characteristic for the representatives of L. maculans and L. biglobosa. Isolates of L. maculans were studied to identify a mating type and avirulence alleles AvrLm1 and AvrLm6. Mating types MAT1.1 and MAT1.2 were found in similar frequencies at all sites, what suggests that both types are well adapted to environment. The AvrLm1 avirulence allele was observed only in isolates obtained at one collection site. For the first time in Poland the avrLm6 virulence allele has been found.