Plant growth promoting rhizobacteria (PGPR) are potential natural alternatives to chemical fungicides in greenhouse production via inducing plant immune system against biotic stresses. In this research, 126 Streptomyces isolates were recovered from rhizosphere soils of 13 different commercial vegetable greenhouses in Iran. Streptomyces isolates were screened for in vitro Plant growth promoting (PGP) traits and ability to antagonize Fusarium oxysporum f. sp. lycopersici race 3 (FOL), the causal agent of Fusarium wilt of tomato (FWT). Six isolates with the highest antagonistic activity and at least three PGP traits were selected and compared with chemical fungicide Carbendazim^® in a greenhouse experiment. All bacterial treatments mitigated FWT disease symptoms like chlorosis, stunting and wilting at the same level or better than Carbendazim^®. Strains IC10 and Y28 increased shoot length and shoot fresh and dry weight compared to not inoculated control plants. Phenotypic characterization and 16S rRNA gene sequencing showed, strains IC10 and Y28 were closely related to S. enissocaesilis and S. rochei, respectively. The ability of the superior biocontrol strains to induce antioxidant enzymes activity and systemic resistance (ISR) was investigated. Increased activity of catalase (CAT) in plant treated with both strains as well as an increase in peroxidase (POX) activity in plants treated with Y28 pointed to a strain specific-induced systemic resistance (ss-ISR) in tomato against FOL. The differential induced expression of WRKY70 and ERF1 (two transcription factors involved in plant defense) and LOX and TPX by the analyzed Streptomyces strains, especially after inoculation with FOL, suggests that ss-ISR is triggered at the molecular level.

Cell suspension cultures of Linum album Kotschy ex Boiss. have been reported to produce anticancer podophyllotoxin and its related lignans. In the present study, we investigated the effect of culture filtrate of Fusarium graminearumon growth, and lignan and phenolic compounds in L. album cell culture. After 7 days of pre-culture, the cells were treated with 1% (v/v) of the culture filtrate. Cell growth was reduced, while phodophyllotoxin and lariciresinol production was stimulated reaching a maximum 0.0187 mg/g fresh weight (FW) and 0.0136 mg/g FW 5 days after the treatment, respectively. Also, our results provide evidence that the culture filtrate of F. graminearum can be effective on phenylalanine ammonia-lyase activity and phenolic compounds.

Paclitaxel is the top-selling anticancer medicine in the world. In vitro culture of Corylus avellana has been made known as a promising and inexpensive strategy for producing paclitaxel. Fungal elicitors have been named as the most efficient strategy for enhancing the biosynthesis of secondary metabolites in plant cell culture. In this study, endophytic fungal strain HEF₁₇ was isolated from C. avellana and identified as Camarosporomyces flavigenus. C. avellana cell suspension culture (CSC) elicited with cell extract (CE) and culture filtrate (CF) derived from strain HEF₁₇, either individually or combined treatment, in mid and late log phase was processed for modeling and optimizing growth and paclitaxel biosynthesis regarding CE and CF concentration levels, elicitor adding day, and CSC harvesting time using multilayer perceptron-genetic algorithm (MLP-GA). The results displayed higher accuracy of MLP-GA models (0.89–0.95) than regression models (0.56–0.85). The great accordance between the predicted and observed values of output variables (dry weight, intracellular, extracellular and total yield of paclitaxel, and also extracellular paclitaxel portion) for both training and testing subsets supported the excellent performance of developed MLP-GA models. MLP-GA method presented a promising tool for selecting the optimal conditions for maximum paclitaxel biosynthesis. An Excel^® estimator, HCC-paclitaxel, was designed based on MLP-GA model as an easy-to-use tool for predicting paclitaxel biosynthesis in C. avellana CSC responding to fungal elicitors.