Expression of L-amino acid oxidase of Trichoderma harzianum in tobacco confers resistance to Sclerotinia sclerotiorum and Botrytis cinerea.

L-amino acid oxidase (ThLAAO) secreted by Trichoderma harzianum ETS323 is a flavoenzyme with antimicrobial characteristics. In this study, we transformed the ThLAAO gene into tobacco to elucidate whether ThLAAO can activate defense mechanisms and confer resistance against phytopathogens. Transgenic tobacco overexpressing ThLAAO showed enhanced resistance against Sclerotinia sclerotiorum and Botrytis cinerea and activated the expression of defense-related genes and the genes involved in salicylic acid, jasmonic acid, and ethylene biosynthesis accompanied by substantial accumulation of H2O2 in chloroplasts, cytosol around chloroplasts, and cell membranes of transgenic tobacco. Scavenge of H2O2 with ascorbic acid abolished disease resistance against B. cinerea infection and decreased the expression of defense-related genes. ThLAAO-FITC application on tobacco protoplast or overexpression of ThLAAO-GFP in tobacco revealed the localization of ThLAAO in chloroplasts. Chlorophyll a/b binding protein (CAB) was isolated through ThLAAO-ConA affinity chromatography. The pull down assay results confirmed ThLAAO-CAB binding. Application of ThLAAO-Cy5.5 on cabbage roots promptly translocated to the leaves. Treatment of ThLAAO on cabbage roots induces systemic resistance against B. cinerea. Overall, these results demonstrate that ThLAAO may target chloroplast and activate defense mechanisms via H2O2 signaling to confer resistance against S. sclerotiorum and B. cinerea.

Gene-to-Gene Network Analysis of the Mediation of Plant Innate Immunity by the Eliciting Plant Response-Like 1 (Epl1) Elicitor of Trichoderma formosa.

A new clade, Trichoderma formosa, secretes eliciting plant response-like 1 (Epl1), a small peptide elicitor that stimulates plant immunity. Nicotiana benthamiana pretreated with Epl1 for 3 days developed immunity against Tomato mosaic virus (ToMV) infection. The transcriptome profiles of T. formosa and N. benthamiana were obtained by deep sequencing; the transcript of Epl1 is 736 nt in length and encodes a 12-kDa peptide. Identifying critical genes in Epl1-mediated immunity was challenging due to high similarity between the transcriptome expression profiles of Epl1-treated and ToMV-infected N. benthamiana samples. Therefore, an efficient bioinformatics data mining approach was used for high-throughput transcriptomic assays in this study. We integrated gene-to-gene network analysis into the ContigViews transcriptome database, and genes related to jasmonic acid and ethylene signaling, salicylic acid signaling, leucine-rich repeats, transcription factors, and histone variants were hubs in the gene-to-gene networks. In this study, the Epl1 of T. formosa triggers plant immunity against various pathogen infections. Moreover, we demonstrated that high-throughput data mining and gene-to-gene network analysis can be used to identify critical candidate genes for further studies on the mechanisms of plant immunity.

Concentrations and analysis of health risks of ambient air metallic elements at Longjing site in central Taiwan.

The concentrations of particulates and metallic elements that were bound to total suspended particulates in ambient air at Long Cyuan Elementary School (LCYES), Lung Ching Elementary School (LCHES) and Long Shan Primary School (LSPS) sampling sites in the Longjing area were measured. Significant difference tests were conducted at LSPS, LCYES and LCHES sites. Finally, carcinogenic and non-carcinogenic risk values for LSPS, LCYES and LCHES sites in the Longjing district were evaluated. The results show that the most average particulate and metallic element concentrations were highest in October, November, January, February, March, April, August, and September The average particulate and metallic element concentrations at LCHES were higher than at the other sampling sites. The Concentration Scatter Diagrams reveal the absence of significant variation among the LSPS, LCYES and LCHES sampling sites in the Longjing district. Therefore, these sampling sites are inferred to have similar emission sources. The children and adults inhalation carcinogenic risks which referenced US EPA method were all within acceptable ranges. Non-carcinogenic risks revealed that all metallic elements considered herein were harmless to human health.

Involvement of pachybasin and emodin in self-regulation of Trichoderma harzianum mycoparasitic coiling.

Our aim was to determine the effects of two secondary metabolites secreted by Trichoderma harzianum, pachybasin and emodin, on the mycoparasitic coiling behavior and cAMP content of T. harzianum. The number of T. harzianum coils around Nylon 66 fiber was increased in the presence of R. solani. The number of T. harzianum coils around R. solani hyphae and Nylon 66 fiber were significantly increased in the presence of pachybasin and emodin. The cAMP level in T. harzianum was significantly increased by close contact with R. solani and much higer cAMP level in the presence of exogenous pachybasin and emodin. A cAMP inhibitor diminished the effect of pachybasin and emodin on T. harzianum coiling around Nylon 66 fiber. The results suggest that pachybasin and emodin mediate the increase in the number of Trichoderma mycoparasitic coils via cAMP signaling. This is the first report to suggest that pachybasin and emodin play roles in the biocontrol mechanism of Trichoderma.

Medium optimization for polysaccharide production of Cordyceps sinensis.

As a potential anticarcinogenic agent, polysaccharides from Cordyceps sinensis have been demonstrated to possess strong antioxidation activity. The aim of the present research was to study the optimal medium to produce polysaccharides of C. sinensis by using response surface methodology (RSM). The composition of optimized medium for polysaccharide production calculated from the regression model of RSM was 6.17% sucrose, 0.53% corn steep powder, 0.5% (NH4)2HPO4, and 0.15% KH2PO4 at pH 4.44, with a predicted maximum polysaccharide production of 3.17 g/L. When applying this optimal medium, the maximum polysaccharide production was 3.05 and 3.21 g/L in a shake flask and a 5-L jar fermentor, respectively. When the pH was controlled at a higher level such as pH 5.0, both cell growth and polysaccharide production were inhibited. A low pH of 2.85 was required for maximum production of polysaccharides.