Powdery mildew of grasses and cereals (Blumeria graminis) is a fungal plant disease which is caused by species of fungi from the Erysiphaceae order. B. graminis is a biotrophic parasite, biologically diverse parasite with a high degree of specialization in certain host species and with numerous physiological breeds adapted to different varieties of a particular host species. In Poland, powdery mildew of cereals and grasses is recorded every year, and its greatest intensity is in south-eastern and south-western regions. The degree of infestation by B. graminis varies every year. This means that the disease occurs every year, in greater or lesser severity. Therefore, it requires monitoring (harmfulness thresholds) and chemical control practically in every vegetation season. Nowadays, an important role is played by immunological breeding. In breeding programs, resistance genes from wild crop forms, primitive and indigenous varieties are an effective tool. The introduction of effective resistance genes into cultivated varieties is a common procedure used in breeding program.<br />The aim of this study was to describe the fungal disease of plants from the group of powdery mildews caused by <br /> B. graminis as an overview.
Barley recombinant lines obtained from crosses and backcrosses of common barley (Hordeum vulgare L.) cultivars Emir and Golden Promise with bulbosus barley grass (H. bulbosum L.) were tested against differential set of 14 Blumeria graminis D.C. Golovin ex Speer f. sp. hordei-synamorph Erysiphe graminis DC. f. sp. hordei Em Marchall isolates, pathogenic fungus causing powdery mildew. Powdery mildew resistance was found in 22 from 24 lines tested. Presence of unknown genes was postulated in 13 lines. In six of these lines the unknown genes were postulated present besides Mla12 allele originated from H. vulgare parent (cv. Emir). The only line resistant to infection, from all isolates used, was 181P94/1/3/1/1/1-2. Four other lines could be considered highly resistant, because they were susceptible to only one powdery mildew isolate. The possibilities to use the hybrid lines with identified resistance to powdery mildew, especially line 181P94/1/3/1/1/1-2 in barley breeding programs were discussed.
This paper presents a method of Agrobacterium-mediated transformation for two diploid breeding lines of potato, and gives a detailed analysis of reporter gene expression. In our lab, these lines were also used to obtain tetraploid somatic hybrids. We tested four newly prepared constructs based on the pGreen vector system containing the selection gene nptII or bar under the 35S or nos promoter. All these vectors carried gus under 35S. We also tested the pDM805 vector, with the bar and gus genes respectively under the Ubi1 and Act1 promoters, which are strong for monocots. The selection efficiency (about 17%) was highest in the stem and leaf explants after transformation with pGreen where nptII was under 35S. About half of the selected plants were confirmed via PCR and Southern blot analysis to be transgenic and, depending on the combination, 0 to 100% showed GUS expression. GUS expression was strongest in multi-copy transgenic plants where gus was under Act1. The same potato lines carrying multi-copy bar under Ubi1 were also highly resistant to the herbicide Basta. The suggestion of using Agrobacterium-mediated transformation of diploid lines of potato as a model crop is discussed herein.
The cell wall plays a crucial role in plant growth and development, including in response to environmental factors, mainly through significant biochemical and biomechanical plasticity. The involvement of the cell wall in C4 plants’ response to cold is, however, still poorly understood. Miscanthus × giganteus, a perennial grass, is generally considered cold tolerant and, in contrast to other thermophilic species such as maize or sorgo, can maintain a relatively high level of photosynthesis efficiency at low ambient temperatures. This unusual response to chilling among C4 plants makes Miscanthus an interesting study object in cold acclimation mechanism research. Using the results obtained from employing a diverse range of techniques, including analysis of plasmodesmata ultrastructure by means of transmission electron microscopy (TEM), infrared spectroscopy (FTIR), and biomechanical tests coupled with photosynthetic parameters measurements, we present evidence for the implication of the cell wall in genotype-specific responses to cold in this species. The observed reduction in the assimilation rate and disturbance of chlorophyll fluorescence parameters in the susceptible M3 genotype under cold conditions was associated with changes in the ultrastructure of the plasmodesmata, i.e., a constriction of the cytoplasmic sleeve in the central region of the microchannel at the mesophyll–bundle sheath interface. Moreover, this cold susceptible genotype was characterized by enhanced tensile stiffness, strength of leaf wall material, and a less altered biochemical profile of the cell wall, revealed by FTIR spectroscopy, compared to cold tolerant genotypes. These changes indicate that a decline in photosynthetic activity may result from a decrease in leaf CO2 conductance due to the formation of more compact and thicker cell walls and that an enhanced tolerance to cold requires biochemical wall remodelling. Thus, the well-established trade-off between photosynthetic capacity and leaf biomechanics found across multiple species in ecological research may also be a relevant factor in Miscanthus’ tolerance to cold. In this paper, we demonstrate that M. giganteus genotypes showing a high degree of genetic similarity may respond differently to cold stress if exposed at earlier growing seasons to various temperature regimes, which has implications for the cell wall modifications patterns.
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