Effect of cyanobacteria and eukaryotic algae on the resistance of tobacco plants against Tobacco mosaic virus

Author(s)

André Boldrin Beltrame

• Document type: Master's Dissertation
• Press: Piracicaba.
• Institution: Universidade de São Paulo (USP). Escola Superior de Agricultura Luiz de Queiroz (ESALA/BC)
• Defense date: 2006-01-26

Examining board members

Sergio Florentino Pascholati; Marli de Fatima Fiore; Robson Marcelo Di Piero

• Advisor: Sergio Florentino Pascholati

Abstract

Algae produce several different compounds that show biological activity, including ones with antiviral activity or that act as phytoalexin inducers. Thus, it was investigated the reduction of Tobacco mosaic virus (TMV) symptoms on tobacco plants treated with cyanobacteria or eukaryotic algae, and it was studied the way of action of algae on the studied pathosystem. When the tobacco plants were treated two days before the inoculation, it was verified that the suspension of 004/02, 008/02, 061/02 Anabaena sp., and Nostoc sp. 61 strains as well as the intracellular preparation of 004/02 strain (4 C) and the medium filtrated from 061/02 strain (61 M) reduced TMV symptoms on tobacco plants, cultivar TNN. Furthermore, it was studied the direct effect of the algae suspensions on virus particles. The results showed that Anabaena sp., Nostoc sp. 21, Nostoc sp. 61 and 090/02 strains have compounds with direct activity on TMV. To try to elucidate the way of the action of algae, on the studied pathosystem, several biochemical parameters were investigated. It was seen that the preparation 4 C increase peroxidase activity and all treatments decrease β-1,3-glucanase activity on tobacco leaves from the forth day on after the treatment. Moreover, 008/02 and 061/02 strains and the 61 M preparation caused higher superoxide accumulation, and the preparation 4 C decreased hydrogen peroxide accumulation when compared to the controls distilled water and BG 11 medium 37 hour after virus inoculation. In this way, the algae could be a biocontrol agents, because it shows direct action on phytopathogens and/or change the metabolism of the plants, that could be associated with the synthesis of deffence compounds. (AU)