Enhancement of plant growth, acclimatization, salt stress tolerance and verticillium wilt disease resistance using plant growth-promoting rhizobacteria (PGPR) associated with plum trees (Prunus domestica)

Plants interact with a great variety of microorganisms that inhabit the rhizosphere playing critical roles in several aspects of plant growth and protection against abiotic and biotic diseases. In this study, we performed a screening of bacteria associated with the rhizosphere of Prunus domestica trees to identify bacterial strains with plant growth-promoting activity. Ten strains isolated from the rhizosphere of P. domestica showed multiple in vitro plant growth promoting rhizobacteria (PGPR) activity such as the production of indole acetic acid, hydrogen cyanide, ammonia, solubilization of phosphates and antifungal activity against Verticillium dalhiae and Fusarium oxysporum f.sp. melonis. In planta, they significantly increased the growth (stem length, number of leaflets, leaf area and root weight) and biochemical (nitrate reductase activity, proline and chlorophyll content) parameters of tomato, as well as the rate of seed germination. Two selected strains (Pr7 and Pr8) with higher antagonistic activity against V. dalhiae and F. oxysporum f.sp. melonis protected tomato plants against Verticillium wilt and salt stress. In addition, they enhanced acclimatization of Vitis vinifera cv. Pinot noir and the peach root stock GF305 from in vitro to the greenhouse. 16S rRNA sequencing identified strains Pr7 and Pr8 as Pseudomonas stutzeri and Bacillus toyonensis, respectively. Since these two PGPR inoculants exhibited multiple traits beneficial to the examined host plants, they may be applied in the development of safe, and effective seed treatments as an alternative to chemical fungicides and fertilization but also for successful acclimatization of micropropagated plants.Mohamed Faize was supported by funding from the ‘Ministère de l'Enseignement Supérieur, de la Recherche Scientifique de la Formation des Cadres’ (MERSFC, Morocco) within the framework of ARIMNet2 Projec

A new homobimetallic cobalt(II) complex based on the tetradentate 3,5-bis(2-pyridyl)-1H-1,2,4-triazole ligand: Synthesis, crystal structure, Hirshfeld analysis, spectroscopic characterization, magnetic properties and antimicrobial activities

International audienceA novel homobimetallic cobalt(II) complex, [Co2(bpt)2(H2O)4](NO3)2.2H2O (bpt = 3,5-bis(2pyridyl)-1,2,4-triazolate), has been synthesized and characterized by single crystal X-ray diffraction, Hirshfeld surface analysis, as well as UV-Visible, and FTIR techniques. The crystal structure determination shows that the dinuclear complex crystallizes in triclinic crystal system with P1 ̅ space group. The (N',N 1 ,N 2 ,N'')2 double bridging coordination mode is realised with distorted octahedral N4O2-coordinated cobalt. The structure cohesion is ensured by different intermolecular hydrogen bonds, π-π stacking interactions and by intermolecular lone-pair•••π interactions. The structure consists of dimeric units [Co2(bpt)2] 2+ with a cobalt-cobalt distance of 4.170(2) Å. Magnetic measurements carried out on the homobimetallic complex indicate a relatively weak antiferromagnetic interaction between the two cobalt centres. This complex exhibited antimicrobial activity against several strains of the fungal phytopathogens Verticillium dahliae and Fusarium oxysporum fsp. melonis as well as against the phytopathogenic bacteria Agrobacterium tumefaciens, suggesting its use in crop protection

Protective effect of symmetrical N‐heterocyclic 1,3,4‐oxadiazole and 1,3,4‐thiadiazole derivatives against Pepino mosaic virus of tomato

International audienceAbstract Pepino mosaic virus (PepMV) is a highly infectious potexvirus, which has presently become a major pathogen for tomato crops worldwide. Since there is no effective method control for PepMV, strict preventive hygienic measures and cross‐protection have been established. However, the use of mild isolates to protect against aggressive isolates provides opportunities for interaction with other microorganisms, which under certain conditions may worsen disease symptoms. Thus, alternative control methods are needed. In this study we aimed at the development of chemical control against PepMV based on the use of heterocyclic compounds including symmetrical 2,5‐disubstituted 1,3,4‐oxadiazoles, symmetrical 2,5‐disubstituted 1,3,4‐thiadiazole and dihydrotetrazine derivatives. Results showed that spray application of three 1,3,4‐oxadiazole derivatives (OH‐Oxa, CH 3 ‐Oxa, NO 2 ‐Oxa) and of the derivative of 1,3,4‐thiadiazole (OH‐Thia) resulted in reducing the main symptoms of PepMV in tomato leaves, conversely to the dihydrotetrazine carboxylic acid. Double‐antibody sandwich enzyme‐linked immunosorbent assay (DAS‐ELISA) revealed that PepMV was not detected from tomato plants pre‐treated with the derivatives conferring elevated protection. Moreover, the protective ability of OH‐Oxa, CH 3 ‐Oxa, NO 2 ‐Oxa and OH‐Thia was closely related to the enhancement of the activity of antioxidant enzymes upon infection with PepMV

Protection of Solanum lycopesicum induced by chitosan and chitosan nano-hydroxyapatite against Pepino mosaic virus and Verticillium dahliae

International audienceThe main of the present study was to prepare chitosan (Chit) and chitosan hydroxyapatite nanoparticle (Chit-nHap) to assess their activities against two major diseases affecting tomato crop: pepino mosaic virus (PepMV) and verticillium wilt caused by the fungus Verticillium dahliae. The synthesized compounds were characterized using X-rays diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), scanning electronic microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). In vitro, the application of various concentrations of Chit and Chit-nHap showed significant inhibition of radial mycelial growth against V. dahliae. However, Chit-nHap was found to be more effective than Chit. In greenhouse trials, the disease severity was significantly reduced when Chit and Chit-nHap were sprayed to the leaves at 150 and 250 mu g mL- 1. The highest concentration of Chit and Chit-nHap reduced leaf alteration index by more than 81% and browning index by 96%. Both compounds also reduced PepMV disease severity and virus accumulation. Protection afforded against PepMV was associated with differential accumulation of H2O2 and with potentiation of the activity of antioxidant enzymes such as catalase, ascorbate peroxidase, guaiacol peroxidase and polyphenol oxidase

Algae and Cyanobacteria as Biocontrol Agents of Fungal Plant Pathogens

none2noAbstract: Since long time, algae are used in agriculture as soil amendment for their beneficial effects on plant health and productivity. In fact, algae contain several molecules such as plant growth hormones (cytokinins, auxins, abscisic and gibberellic acid), polysaccharides, betaines and micronutrients. The research on algae, their compounds and their effects on plants have started in the middle 1950s and brought to the formulations of liquid products containing extracts with compounds readily available for plants. The algae extracts, besides having effects on plant growth, have demonstrated to improve plant resistance to both abiotic and biotic stresses. Among biotic stresses, algae showed antifungal activity against different pathogens especially of horticultural plants. From the middle of last century, plant management has always been dependent from the market demand that required growing quantity of ‘perfect’ fruits and vegetables over the year. In this scenario, the chemical industry of fertilizers and pesticides developed new products that have been used for years. In particular, pesticides have represented the base of the management of fungal plant pathogens. During the last decades, the use of both pesticides and chemical fertilizers has represented a serious risk for human health and brought disorder of ecosystem equilibrium. Consequently, algae for their biostimulant and antifungal effects may be considered useful tools to reduce the input of chemicals in integrated pest management strategies. In line with these strategies, the European Regulation EC 1107/2009, concerning the placing of plant protection products on the market and repealing Council Directives 79/117/ EEC and 91/414/EEC, recommends that priority should be given to non-chemical and natural alternatives wherever possible.mixedHillary Righini; Roberta RobertiHillary Righini; Roberta Robert