Plant-parasitic nematodes are a major threat to crop production in all agricultural systems. The scarcity of classical resistance genes highlights a pressing need to find new ways to develop nematode-resistant germplasm. Here, we sequence and assemble a high-quality phased genome of the model cyst nematode Heterodera schachtii to provide a platform for the first system-wide dual analysis of host and parasite gene expression over time, covering all major parasitism stages. Analysis of the hologenome of the plant-nematode infection site identified metabolic pathways that were incomplete in the parasite but complemented by the host. Using a combination of bioinformatic, genetic, and biochemical approaches, we show that a highly atypical completion of vitamin B5 biosynthesis by the parasitic animal, putatively enabled by a horizontal gene transfer from a bacterium, is required for full pathogenicity. Knockout of either plant-encoded or now nematode-encoded steps in the pathway significantly reduces parasitic success. Our experiments establish a reference for cyst nematodes, further our understanding of the evolution of plant-parasitism by nematodes, and show that congruent differential expression of metabolic pathways in the infection hologenome represents a new way to find nematode susceptibility genes. The approach identifies genome-editing-amenable targets for future development of nematode-resistant crops.

Cyst nematodes induce specific syncytial feeding structures within the root which develop from an initial cell by successive incorporation of neighbouring cells through local cell wall dissolutions followed by hypertrophy of included cells. Expansins are known to induce cell wall relaxation and extension in acidic pH, and they are involved in many processes requiring wall modification from cell expansion to cell wall disassembly. We studied the expression pattern of tomato (Lycopersicon esculentum L., cv. Money Maker) expansins during development of syncytia induced by the potato cyst nematode (Globodera rostochiensis Woll.). Based on semi-quantitative reverse transcription-polymerase chain reaction, two expansin genes, LeEXPA4 and LeEXPA5, were selected for detailed examinations because their expression was either elevated in infected roots (LeEXPA4) or specifically induced in the root upon nematode infection (LeEXPA5). Both genes have distinct spatial and temporal expression patterns that may reflect their different roles in syncytium development. LeEXPA4 transcripts were localized predominantly in parenchymatous vascular cylinder cells surrounding syncytia. This finding suggests that LeEXPA4 might be involved in cell wall disassembly or relaxation, mediating syncytium expansion and/or development of conductive tissues. By contrast, LeEXPA5 transcripts were localized in enlarging syncytial elements. Similarly, in immunogold localization experiments, polyclonal antibodies localized the LeEXPA5 protein in cell walls of syncytial elements. This expression pattern suggests that LeEXPA5 gene is specifically involved in enlargement of cells incorporated into syncytium.

For the proliferation of their feeding sites (syncytia), the potato cyst nematode Globodera rostochiensis is thought to recruit plant endo-beta-1,4-glucanases (EGases, EC. 3.2.1.4). Reverse-transcription polymerase chain reaction experiments on tomato (Solanum lycopersicum) indicated that the expression of two out of the at least eight EGases, namely Sl-cel7 and Sl-cel9C1, is specifically upregulated during syncytium formation. In situ hybridization and immunodetection studies demonstrated that both EGases are specifically expressed inside and adjacent to proliferating syncytia. To assess the importance of Sl-cel7 and Sl-cel9C1 for nematode development, we decided to knock them out individually. Sl-cel9C1 probably is the only class C EGase in tomato, and we were unable to regenerate Sl-cel9C1-silenced plants. Potato (S. tuberosum), a close relative of tomato, harbors at least two class C EGases, and St-cel7-or St-cel9C1-silenced potato plants showed no obvious aberrant phenotype. Infection with potato cyst nematodes resulted in a severe reduction of the number of adult females (up to 60%) and a sharp increase in the fraction of females without eggs (up to 89%). Hence, the recruitment of CEL7, an enzyme that uses xyloglucan and noncrystalline cellulose as natural substrates, and CEL9C1, an enzyme that uses crystalline cellulose, is essential for growth and development of potato cyst nematodes.

The aim of this study was to evaluate selected quality attributes of pork longissimus lumborum (ll) muscle characterized by Rfn and PSe occurrence considering its microstructure. The material used in the research was 100 pork meat samples of normal quality (RFN -red, firm, normal, non-exudative) and 100 pork meat samples with PSe defect. The digital images of microstructure of selected meat samples were captured and some quality attributes, including ph level, drip loss, electrical conductivity (ec), water holding capacity (Whc) and ciel*a*b* parameters, were determined. Based on the findings obtained it was concluded that PSE meat (pH 24h ≤5.5) was characterized by higher degradation of muscle fibre structure when compared with the normal meat (RFN). The differences in the microstructure of PSE and RFN meat influenced the colour, electrical conductivity, drip loss and WHC of the meat. The PSE meat was characterized by a significantly lighter color and significantly higher electrical conductivity, along with more intense drip loss and worsened water holding capacity in comparison with Rfn meat. key words: meat quality, microstructure, PSe defectThe occurrence of meat defects has recently received much attention from many scientists and processors as PSE meat has been shown to have poor processing parameters and decreased consumer acceptance (O'Neill et al., 2003). Meat with PSE is a major quality defect facing the entire swine industry. The incidence of PSE meat is, first of all, associated with rapid postmortem glycolysis. It results in fast and abnormal accumulation of excess lactic acid in the muscles. High postmortem acidification rate of muscle tissue and increased carcass temperature (even up to 40°C)

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