Background Colonization of Trichoderma spp. is essential for exerting their beneficial functions on the plant. However, the interactions between Trichoderma spp. and plant roots are still not completely understood. The aim of this study was to investigate how Tg SWO affect Trichoderma guizhouense to establish themselves in the plant rhizosphere and promote plant growth. In this study, we deeply analyzed the molecular mechanism by which the functional characterization of the Tg SWO by expressing different functional region deletion proteins (FRDP) of Tg SWO. Results Root scanning analysis results showed that Tg SWO could dramatically increase root density and promote growth. In addition, we also found that Tg SWO could expand root cell walls, subsequently increase root colonization. Moreover, knockout of Tg SWO mutants (KO) or overexpression of Tg SWO mutants (OE) produced greatly reduced or increased the number of cucumber root, respectively. To clarify the molecular mechanism of Tg SWO in plant-growth-promotion, we analyzed the ability of different FRDP to expand the root cell wall. The root cell wall architecture were considerably altered when treated by ΔCBD protein (the Tg SWO gene of lacking in the CBD domain was cloned and heterologously expressed), in correlation with the present YoaJ domain of Tg SWO. In contrast, neither the expansion of cell walls nor the increase of roots was detectable in ΔYoaJ protein. Conclusions Our results emphasize the YoaJ domain is the most critical functional area of Tg SWO during the alteration of cell wall architecture. Simultaneously, the results obtained in this study also indicate that Tg SWO might play a plant-growth-promotion role in the Trichoderma -plant interactions by targeting the root cell wall.

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Trichoderma spp. is a cosmopolitan group of soil fungi which plays a remarkable role in stimulating plant growth after interacting with plant roots and has good application prospects in intensive agriculture. In this study, rice straw and amino acids improved the population of Trichoderma guizhouense NJAU4742 under solid-state fermentation and helped us develop a new type of organic fertilizer. The effects of this biological organic fertilizer were evaluated in the growth of peppers (Capsicum annuum L.) for two seasons under sandy and mountain soils. In the first season, the yields in T6 (0.06% solid fermentation products in soil) and AT6 (added 0.06% solid fermentation products and 1% amino acid organic fertilizer in soil) treatments were increased by 41.8% and 52.3% in sandy soil and by 51.6% and 46.5% in mountain soil, respectively, compared with chemical fertilizer. During the second season, the same trend was obtained in both sandy and mountain soils. Soil peroxidase activity (125.2 μmol·g−1 dw), urease activity (58.7 μmol·g−1 dw) and invertase activity (13.11 mg·g−1 dw) reached their highest levels in biological organic fertilizer compared to the treatments with chemical fertilizer and solid fermentation products. Redundancy analysis showed that crop yield was positively correlated with enzyme activities, soil organic carbon, total nitrogen, and available phosphorus. Thus, we demonstrated that NJAU4742-enriched biological organic fertilizer could accelerate the transformation of nutrients and promote pepper growth.

Aims:  The aim of this study is to improve exoinulinase production by expression of a cloned exoinulinase gene inuA1 (GenBank accession no. ) from Penicillium janthinellum strain B01 in Pichia pastoris. Methods and Results:  A full‐length cDNA of exoinulinase gene (inuA1) was cloned from P. janthinellum strain B01 using RACE PCR. An open reading frame (ORF) of 2115 bp is interrupted by a single intron of 67 bp. The fragment encodes a signal peptide with 20 amino acids and a mature protein with 684 amino acids. The inuA1 was subcloned to the pPICZαC expression vector and succesfully over‐expressed in Pichia pastoris X‐33. The highest activity of exoinlinase reached 272·8 U ml−1 in the fermentation liquid. It was c. 11‐fold of that produced by wild‐strain B01. A large amount of fructose was identified after the hydrolysis of inulin with the crude recombinant exoinulinase. The recombinant exoinulinase was purified and characterized. The molecular weight of the purified recombinant exoinulianse was 100 kDa. The mass spectrometry result indicated that the purified protein was indeed recombinant exoinulinase. The optimal pH and temperature of the purified recombinant exoinulianse were 4·5 and 50°C, respectively. Conclusions:  An exoinulinase gene of P. janthinellum strain B01 was cloned, sequenced and over‐expressed successfully in P. pastoris. Significance and Impact of the Study:  Only a few genes have been cloned from P. janthinellum because its molecular biology is poorly understood. In this study, we cloned and over‐expressed inuA1 gene of P. janthinellum in P. pastoris. This recombinant exoinulinase can be used to hydrolyse inulin to produce fructose and facilitate the biofuel production from inulin resources.

Opportunity costs seriously limit the large-scale production of bio-organic fertilizers (BOFs) both in China and internationally. This study addresses the utilization of amino acids resulting from the acidic hydrolysis of pig corpses as organic nitrogen sources to increase the density of TrichodermaharzianumT-E5 (a typical plant growth-promoting fungi, PGPF). This results in a novel, economical, highly efficient and environmentally friendly BOF product. Fluorescence excitation-emission matrix (EEM) spectroscopy combined with fluorescence regional integration (FRI) was employed to monitor compost maturity levels, while pot experiments were utilized to test the effects of this novel BOF on plant growth. An optimization experiment, based on response surface methodologies (RSMs), showed that a maximum T-E5 population (3.72 × 108 ITS copies g−1) was obtained from a mixture of 65.17% cattle manure compost (W/W), 19.33% maggot manure (W/W), 15.50% (V/W)hydrolytic amino acid solution and 4.69% (V/W) inoculum at 28.7°C after a 14 day secondary solid fermentation. Spectroscopy analysis revealed that the compost transformation process involved the degradation of protein-like substances and the formation of fulvic-like and humic-like substances. FRI parameters (PI, n, PII, n, PIII, n and PV, n) were used to characterize the degree of compost maturity. The BOF resulted in significantly higher increased chlorophyll content, shoot length, and shoot and root dry weights of three vegetables (cucumber, tomato and pepper) by 9.9%~22.4%, 22.9%~58.5%, 31.0%~84.9%, and 24.2%~34.1%, respectively. In summary, this study presents an operational means of increasing PGPF T-E5 populations in BOF to promote plant growth with a concomitant reduction in production cost. In addition, a BOF compost maturity assessment using fluorescence EEM spectroscopy and FRI ensured its safe field application.