Project description:Composts are the products obtained after the aerobic degradation of different types of organic matter wastes and can be used as substrates or substrate/soil amendments. There are a small but increasing number of reports that suggest that foliar diseases may be reduced when using compost as growing medium compared to standard substrates. The purpose of this study was to unravel the gene expression alteration produced by the compost to gain knowledge about the mechanisms involved in the compost-induced systemic resistance. A compost from olive marc and olive tree leaves was able to induce resistance against Botrytis cinerea in Arabidopsis compared to the standard substrate perlite. Microarray analyses revealed that 178 genes were differently expressed with a fold change cut off of 1 from which 155 were upregulated and 23 were down regulated in compost-grown compared to perlite-grown plants. Functional enrichment study of up regulated genes revealed that 38 Gene Ontology terms were significantly enriched. Response to stress, biotic stimulus, other organism, bacterium, fungus, chemical and abiotic stimulus, SA and ABA stimulus, oxidative stress, water, temperature and cold were significantly enriched terms as well as immune and defense responses, systemic acquired resistance, secondary metabolic process and oxireductase activity. Interestingly, PR1 expression, which was equally enhanced by growing the plants in compost and by B. cinerea inoculation, was further boosted in compost-grown pathogen-inoculated plants. Compost triggered a plant response that shares similarities with both systemic acquired resistance and ABA dependent/independent abiotic stress responses.
Project description:BackgroundThe importance of the accessory enzymes such as α-L-arabinofuranosidases (AFases) in synergistic interactions within cellulolytic mixtures has introduced a paradigm shift in the search for hydrolytic enzymes. The aim of this study was to characterize novel AFase genes encoding enzymes with differing temperature optima and thermostabilities for use in hydrolytic cocktails.ResultsThree fosmids, pFos-H4, E3 and D3 were selected from the cloned metagenome of high temperature compost, expressed in Escherichia coli and subsequently purified to homogeneity from cell lysate. All the AFases were clustered within the GH51 AFase family and shared a homo-hexameric structure. Both AFase-E3 and H4 showed optimal activity at 60 °C while AFase-D3 had unique properties as it showed optimal activity at 25 °C as well as the ability to maintain substantial activity at temperatures as high as 90 °C. However, AFase-E3 was the most thermostable amongst the three AFases showing full activity even at 70 °C. The maximum activity was observed at a pH profile between pH 4.0-6.0 for all three AFases with optimal activity for AFase H4, D3 and E3 at pH 5.0, 4.5 and 4.0, respectively. All the AFases showed KM range between 0.31 mM and 0.43 mM, Kcat range between 131 s- 1 and 219 s- 1 and the specific activity for AFase-H4, AFases-E3 and was 143, 228 and 175 U/mg, respectively. AFases-E3 and D3 displayed activities against pNP-β-L-arabinopyranoside and pNP-β-L-mannopyranoside respectively, and both hydrolysed pNP-β-D-glucopyranoside.ConclusionAll three AFases displayed different biochemical characteristics despite all showing conserved overall structural similarity with typical domains of AFases belonging to GH51 family. The hydrolysis of cellobiose by a GH51 family AFase is demonstrated for the first time in this study.
Project description:Composts are the products obtained after the aerobic degradation of different types of organic matter wastes and can be used as substrates or substrate/soil amendments. There are a small but increasing number of reports that suggest that foliar diseases may be reduced when using compost as growing medium compared to standard substrates. The purpose of this study was to unravel the gene expression alteration produced by the compost to gain knowledge about the mechanisms involved in the compost-induced systemic resistance. A compost from olive marc and olive tree leaves was able to induce resistance against Botrytis cinerea in Arabidopsis compared to the standard substrate perlite. Microarray analyses revealed that 178 genes were differently expressed with a fold change cut off of 1 from which 155 were upregulated and 23 were down regulated in compost-grown compared to perlite-grown plants. Functional enrichment study of up regulated genes revealed that 38 Gene Ontology terms were significantly enriched. Response to stress, biotic stimulus, other organism, bacterium, fungus, chemical and abiotic stimulus, SA and ABA stimulus, oxidative stress, water, temperature and cold were significantly enriched terms as well as immune and defense responses, systemic acquired resistance, secondary metabolic process and oxireductase activity. Interestingly, PR1 expression, which was equally enhanced by growing the plants in compost and by B. cinerea inoculation, was further boosted in compost-grown pathogen-inoculated plants. Compost triggered a plant response that shares similarities with both systemic acquired resistance and ABA dependent/independent abiotic stress responses. Global gene expression of plants grown in compost (3 biological replicates) versus plants grown in perlite (2 biological replicates) was studied.