Copper complexes of the 1,3,4-thiadiazole derivatives modulate antioxidant defense responses and resistance in tomato plants against fungal and bacterial diseases

• Published in: Pesticide biochemistry and physiology 2017-11, Vol.143, p.26-32
• Main Authors: Smaili, Amal, Rifai, Lalla Aicha, Esserti, Siham, Koussa, Tayeb, Bentiss, Fouad, Guesmi, Salaheddine, Laachir, Abdelhakim, Faize, Mohamed
• Format: Article
• Language: English
• Subjects: Copper complexes; Crown gall, active oxygen species, antioxidant defenses; Tomato; Verticillium wilt
• ISSN: 0048-3575; 1095-9939
• DOI: 10.1016/j.pestbp.2017.10.002

The metallic complexes μ-chloro-μ-[2,5-bis (2-pyridyl)-1,3,4-thiadiazole] aqua chlorocopper (II) dichlorocopper (II) (abbreviated 2PTH-Cu2-Cl4); aquabis [2,5-bis (2-pyridyl)-1,3,4-thiadiazole-κ2N2,N3] (trifluoromethane-sulfonato-κO) copper(II) trifluoro metrhanesulfonate (2PTH-Cu-tF) and bis[(2,5-bis(pyridine-2-yl)-1,3,4-thiadiazole-di-azido copper(II)] (2PTH-Cu-Az) were compared for their antimicrobial activities in vitro, and their aptitude to control Verticillium wilt and crown gall diseases development of tomato in the greenhouse. Results showed that the complex 2PTH-Cu-Az inhibited drastically the growth of V. dahliae in vitro. 2PTH-Cu2-Cl4 and 2PTH-Cu-tF did not display any noticeable antimicrobial activity in vitro against all of the pathogens tested. However, in planta evaluation revealed that the three complexes protected tomato against crown gall similarly. They also reduced Verticillium wilt disease severity, although the complex 2PTH-Cu-Az was the most efficient. When compared to other complexes, 2PTH-Cu-Az triggered only a weak oxidative burst as revealed by H2O2 measurement and the activity of ascorbate peroxidase and catalase. These results suggest that the superiority of 2PTH-Cu-Az against V. dahliae rely on its direct antifungal activity and its ability to modulate H2O2 accumulation. [Display omitted] •Copper complexes 2,5-bis (2-pyridyl)-1,3,4-thiadiazole (2PTH) were tested against Verticillium wilt and crown gall diseases.•The complex 2PTH-Cu-Az exhibits elevated antifungal activity in vitro and elevated protective ability in the greenhouse.•The complexes 2PTH-Cu2-Cl4 and 2PTH-Cu-tF were effective in reducing Verticillium wilt disease severity.•2PTH-Cu-Az triggered only a slight accumulation of H2O2, when compared to the complexes 2PTH-Cu2-Cl4 and 2PTH-Cu-tF.