Fusarium oxysporum f. sp. radicis-lycopersici (FORL) leading to fusarium crown and root rot is one of the most destructive soilborne diseases of tomatoes occurring in greenhouse and field crops. Physiological races of FORL were not defined but nine vegetative compatibility groups (VGCs) were identified. Infection followed by wounds and natural holes and infection is not systemic. The optimum soil temperature for pathogen development is 18°C. Infection may cause plants to wilt and die completely or infection may lower fruit quality. Fusarium oxysporum f. sp. radicis-lycopersici has the ability to produce a specific enzyme, tomatinase, which breaks down α-tomatine and protects the pathogen. In contrast tomato also has a defence system which consists of the enzymes chitinase and β-1, 3-glucanase. Tomato resistance to Fusarium oxysporum f. sp. radicis-lycopersici is determined by a single dominant gene Frl, localized on the long arm of chromosome 9. It was introduced to cultivars from Licopersicum peruvianum (L.) Mill.

Trichodermaspp. - The Cause of Green Mold on Polish Mushroom FarmsThe first reports concerning green mold on Polish mushroom farms are from 2002. In Europe and the United StatesTrichoderma harzianumwas initially described as a causative agent of the disease. However, soon two biotypes ofTrichoderma, Th2 in Europe and Th4 in America, were recognised as responsible for commercial losses and were designated as a new species namedT. aggressivum.Until now it has not been clear which species ofTrichodermaand which form of the species was a causative agent of the disease outbreak in Poland and what was the main source of infection. Therefore, studies were conducted on the composition of theTrichodermaspecies in Polish mushroom farms and in compost samples. The isolates were identified by phenotypic and microscopic studies. The classification of the strains recognised asT. aggressivumwas then confirmed by PCR methods. The aggressiveness ofTrichodermaspp., especiallyT. aggressivum, was estimated inin vitrostudies. The most frequently isolatedTrichodermaspp. were:T. harzianum, T. aggressivum, T. atrovirideandT. longibrachiatum.Using the technique of PCR, multiplex PCR and PCR-RAPD it was determined that 24 isolates from Polish mushroom farms belonged toT. aggressivumf.europeanum(Th2). However, a large variation between isolates indicated the possibility that Polish biotypes ofT. aggressivumwere different from those, which were found in western Europe. All isolates ofT. aggressivumwere highly pathogenic towardsAgaricus bisporus.

Foliar application of a mixture of herbicides containing phenmedipham, desmedipham and ethofumesate to the plants of nine strawberry culfivars revealed that there were differences in the level of plant tolerance to the applied chemicals. Light, polarized light and scanning electron microscopy were used to explain differences in tolerance to herbicides. The surface of strawberry leaves and cells was examined for stomata, hairs, trichomes, surface structures, cucticle, vacuole and oxalate crystals. The thicker the cuticle on the adaxial leaf surface, the thicker the layer of epicuticular waxes, greater number of large vacuoles and greater number of calcium oxalate crystals in epidermis cells were characteristic for cultivars with very good tolerance to herbicides. The cracking of epicuticular waxes layer was typical to cultivars with respectively low tolerance to herbicides.

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SummaryTomato (Solanum lycopersicum L.) is one of the most popular vegetable grown in many regions of the world. Due to its high taste quality and nutritional value increase interest in the cultivation of this species and its consumption. Using the latest achievements in fields of genetics, molecular biology and biotechnology, breeders can create new varieties with improved useful traits. Introduction of DNA markers, especially those based on the polymerase chain reaction (PCR) has led to breakthrough in the plants genetic research, including tomato. They are successfully used for plant genomes mapping, phylogenetics studies, selection of parental forms in plant breeding, and above all to identify the genes of important traits. For tomato have been identified and mapped 9309 molecular markers. High-density genetic maps development gives an opportunity to use them in genetic research and breeding programs. Identification of DNA markers closely linked to studied gene can significantly facilitate the identification of desirable traits in material breeding, or accelerate the plants selection for elimination of genotypes with undesirable genes. Material breeding selection using molecular markers, defined as MAS (marker-assisted-selection) is increasingly being used in tomato breeding programs, contributing to facilitated identification of genes or QTL and their transfer into the cultivated species from wild form.

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The anatomical structure of the tomato (Lycopersicon esculentum Mill.) pericarp was studied in the fruits of five determinant field cultivars. The fruits of the examined cultivars differed in their mechanical properties. Fruits of cultivars which are firm and resistant to injury (Kecskemeti 886j-2, Campbell 28), moderately firm and resistant (Atma, Wenus) and soft, susceptible to injury (line No 155/84) were examined. The pericarp of the cultivars which have fruits resistant to injury had an approx. 200 µm thick covering layer (epidermis plus cuticle plus hypodermis) whereas that of fruits susceptible to injury was only 100 µm thick. In the fruits resistant to injury the cuticle penetrated deeply into the hypodermis, the epidermal cells were flattened and the hypodermis was composed of 4 - 5 rows of cells. The tomato fruits resistant to injury had a thick cuticle layer on their tangential walls - whereas those more susceptible had a thick cuticle layer on these walls

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