Trichoderma spp. are widely used in plant disease control as biocontrol agents. Inducing plant disease resistance is an important biocontrol mechanism of Trichoderma. It is of great significance to explore the factors involved in the surface recognition and interaction of Trichoderma with plants. Hydrophobin is a small molecular protein rich in cysteine in higher filamentous fungi and has been found to participate in the morphogenesis and interaction of fungi with other organisms. In this study, the type II hydrophobic protein-coding gene Thfb6 from T. harzianum TH33 was cloned and heterologously expressed in Escherichia coli BL21 (DE3). The purified recombinant protein Thfb6 induced a hypersensitive response in tobacco leaves, a burst of reactive oxygen species, and an accumulation of callose, phenolic substances, and lignin in tobacco, indicating that Thfb6 can induce an early defense reaction in tobacco. Thfb6 also enhanced the systemic resistance of tobacco against tobacco mosaic virus. The rate of lesion number reduction by treatment with Thfb6 could be up to 36.02%. Thfb6 increased the activity of tobacco defense-related enzymes, including phenylalanine ammonia-lyase (PAL), polyphenol oxidase, and peroxidase, which were all more than three times the control after 3–5 days post treatment of Thfb6. The transcription of resistance-related genes, including the PAL gene, non-expresser of pathogenesis-related gene1 (NPR1), and basic pathogenesis-related gene 1 (PR1-b), were upregulated after Thfb6 treatment. The relative expression levels of the PAL and NPR1 genes were highest on the third and fourth days after Thfb6 treatment, at 5.5 times and 8.3 times that of the control, respectively. The relative expression level of PR1 on the sixth day after Thfb6 treatment was 5.3 times that of the control. These results indicate that the improvement of defense-related enzyme activity and the induced expression of disease-resistance-related genes were the main mechanisms by which Thfb6 induced systemic resistance in tobacco.

Black-purple carrots possess, apart from carotenoids, high content of other bioactive pigments such as anthocyanins. However, both carotenoids and anthocyanins are modified over cold storage due to their lability. In this work, we investigated the effect of the postharvest elicitation on nutritional and organoleptic quality of purple carrots over storage at 5°C for 21 days. Based on our experience, we considered methyl jasmonate and abscisic acid as elicitors. The values obtained were compared with those provided by the fresh-untreated sample on the treatment day (ie, day 0) and after three-week storage (ie, on day 21), which were used as a reference. As a result, carotenoid content increased naturally in untreated samples over storage whereas anthocyanins maintained invariable. Also, physicochemical parameters reflected apparent organoleptic quality loss. However, the postharvest treatment of purple carrot samples with elicitors resulted in similar carotenoid content in elicited samples to fresh carrots on day 0 as well as lower concentration of anthocyanins and antioxidant activity. Besides, elicitation, particularly with abscisic acid, enabled purple carrot deterioration to be slowed down and, therefore, the organoleptic quality to be preserved. This suggests delaying effect of both elicitors on the spoilage rate of purple carrots over the storage time. These findings indicate that the postharvest application of elicitors may be an interesting conservation method, alternative to traditional procedures, to decelerate decomposition and extend shelf-life of purple carrots.

Conventional fluorescent lamps used in tissue culture are costly light sources showing excessive wavelength emission-bandwidth that must be replaced by alternative, less costly and much lower power-consuming energy sources. The use of Light-Emitting Diodes (LEDs) is the best option due to their potential role as elicitors of secondary metabolite production in many plant models. Gynura procumbens(G. procumbens) is widely used for treating various diseases. Here, leaf explants were cultivated in MS medium supplemented with 0.5 mg/L of NAA and 2.0 mg/L of BAP for 30 days under white, blue, and red LEDs. Secondary metabolites were analyzed by HPLC and LC-MS. Blue LEDs elicited the highest antioxidant activity, total flavonoid, and phenolic content. Furthermore, the content of cyanidin-monoglucosides increased significantly increased under blue light.