Application of 3.6 mM silicon (Si+) to the rose (Rosa hybrida) cultivar Smart increased the concentration of antimicrobial phenolic acids and flavonoids in response to infection by rose powdery mildew (Podosphaera pannosa). Simultaneously, the expression of genes coding for key enzymes in the phenylpropanoid pathway (phenylalanine ammonia lyase, cinnamyl alcohol dehydrogenase, and chalcone synthase) was up-regulated. The increase in phenolic compounds correlated with a 46% reduction in disease severity compared with inoculated leaves without Si application (Si2). Furthermore, Si application without pathogen inoculation induced gene expression and primed the accumulation of several phenolics compared with the uninoculated Si2 control. Chlorogenic acid was the phenolic acid detected in the highest concentration, with an increase of more than 80% in Si+ inoculated compared with Si2 uninoculated plants. Among the quantified flavonoids, rutin and quercitrin were detected in the highest concentrations, and the rutin concentration increased more than 20-fold in Si+ inoculated compared with Si2 uninoculated plants. Both rutin and chlorogenic acid had antimicrobial effects on P. pannosa, evidenced by reduced conidial germination and appressorium formation of the pathogen, both after spray application and infiltration into leaves. The application of rutin and chlorogenic acid reduced powdery mildew severity by 40% to 50%, and observation of an effect after leaf infiltration indicated that these two phenolics can be transported to the epidermal surface. In conclusion, we provide evidence that Si plays an active role in disease reduction in rose by inducing the production of antifungal phenolic metabolites as a response to powdery mildew infection.

Powdery mildew, caused by Podosphaera pannosa, is a very common disease in greenhouse potted roses, resulting in poor marketing value and hence economic losses. Alternatives to chemical control are necessary, and therefore the ability of silicon (Si) applied to roots to control the disease was investigated, as well as the mechanisms behind the observed disease reductions. Four genotypes of miniature potted roses representing different genetic backgrounds and susceptibility to disease were studied. Plants were watered with a nutrient solution containing either 3AE6 mM Si (100 ppm) supplied as K 2 SiO 3 (Si+) or no Si (Si)) before inoculation with P. pannosa. Si application increased leaf Si content two-to four-fold compared to control plants. Confocal microscopy showed that Si deposition was larger in Si+ than in Si) plants and that deposition mainly occurred in the apoplast, particularly in epidermal cell walls. Si application delayed the onset of disease symptoms by 1-2 days and disease severity was reduced by up to 48AE9%. The largest reduction was found in the two most resistant genotypes, which also had the highest increase in Si uptake. The Si-induced disease protection was accompanied by increased formation of papillae and fluorescent epidermal cells (FEC) as well as deposition of callose and H 2 O 2 , especially at the sites of penetration and in FEC, which are believed to represent the hypersensitive response. Si treatment reduced powdery mildew development by inducing host defence responses and can therefore be used as an effective eco-friendly disease control measure.

Gluten free products have emerged during the last decades, as a result of a growing public concern and technological advancements allowing gluten reduction in food products. One approach is to use gluten degrading enzymes, typically at low or ambient temperatures, whereas many food production processes occur at elevated temperature. We present in this paper, the discovery, cloning and characterisation of a novel recombinant thermostable gluten degrading enzyme, a proline specific prolyl endoprotease (PEP) from Sphaerobacter thermophiles. The molecular mass of the prolyl endopeptidase was estimated to be 77kDa by using SDS-PAGE. Enzyme activity assays with a synthetic dipeptide Z-Gly-Pro-p-nitroanilide as the substrate revealed that the enzyme had optimal activity at pH 6.6 and was most active from pH 5.0-8.0. The optimum temperature was 63 °C and residual activity after one hour incubation at 63 °C was higher than 75 %. The enzyme was activated and stabilized by Co and inhibited by Mg, K and Ca followed by Zn, Na Mn, Al and Cu. The K and k values of the purified enzyme for different substrates were evaluated. The ability to degrade immunogenic gluten peptides (PQPQLPYPQPQLPY (a-gliadin) and SQQQFPQPQQPFPQQP (γ-hordein)) was also confirmed by enzymatic assays and mass spectrometric analysis of cleavage fragments. Addition of the enzyme during small scale mashing of barley malt reduced the gluten content. The findings here demonstrate the potential of enzyme use during mashing to produce gluten free beer, and provide new insights into the effects of proline specific proteases on gluten degradation.

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Very large amounts of brewer's spent grains (BSG) are produced in the world which is usually considered as a waste, or animal feed, rather than food for humans. Here, we report, for the first time, a new process at pilot scale for the separation of brewer's spent grain and trub to solid and liquid streams that can be used in foods. A new type of continuous rotary drum press was used to process hot BSG to produce a liquid filtrate and a filter cake stream. Analysis showed that of the starting mass of BSG (ca. 120 kg), the liquid filtrate composed 50% of the mass, and the filter cake fraction composed 50% of the mass. The dry weight (DW) content of the BSG increased from 23 to over 35%. This led to concentration of insoluble dietary fibre (from 38 to 54%) and phenolics in the filter cake (from 102 to 150 mg/100 g DW as gallic acid equivalents). No fractionation of soluble species such as proteins occurred. Centrifugation of the filtrate from the rotary drum press led to a clarified supernatant stream and a paste. Concentration of insoluble dietary fibre and phenolics occurred in the paste (from 5 to 14% of DW and 61 to 114 mg/100 g DW as gallic acid equivalents), whereas soluble fibre and protein did not selectively partition. Given that the unit operations used here are scaleable and approved for food production, an industrially feasible route now exists to process brewers spent grains to ingredients.

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BACKGROUND Silicon (Si) application to miniature potted roses can decrease severity of powdery mildew (Podosphaera pannosa) and this is associated with increased accumulation of callose and hydrogen peroxide (H2O2) as well as hypersensitive (HR) cells. We used microscopy, gene expression and specific inhibitors of callose and H2O2 to determine how effective these plant responses are in stopping infection. RESULTS Pathogen arrest in Si‐treated (Si+) plants was accompanied by increased accumulation of callose and H2O2 in papillae and HR cells, respectively. These responses were reduced by application of specific inhibitors (2‐deoxy‐d‐glucose for callose and catalase for H2O2), which increased disease severity in Si+, but not in Si− plants. As markers for HR and callose, expression of the HR‐specific gene hsr203J and the wound‐related callose synthase GSL5, respectively, was studied. An up‐regulation of expression was only seen after isolation of HR cells with laser capture microdissection. The up‐regulation was higher in Si+ than in Si− plants and occurred concomitantly with more efficient photosynthesis in Si+ plants at high disease severity as compared to Si− plants. CONCLUSION Silicon‐mediated activation of callose and H2O2 are decisive factors in the defence of rose against P. pannosa and these responses were accompanied with more efficient photosynthesis to strengthen the plant. Only by isolation of HR cells using laser capture microdissection as compared to analysis of whole leaf tissues allowed detection of elevated transcript levels of hsr203J and GSL5 at infection sites as markers for HR. © 2021 Society of Chemical Industry.