Arbuscular mycorrhizal fungi against the false root-knot nematode activity in Capsicum annuum: Physiological responses in plants

Abstract

Nacobbus aberrans affects plants growth and development, and decreases the production of numerous horticultural crops. Several investigations have shown that symbiosis with arbuscular mycorrhizae can confer tolerance to pathogens through different action mechanisms, such as nutrient space competition and plant resistance induction. The aim of this study was to analyse the potential of three arbuscular mycorrhizal fungi (AMF): Rhizophagus intraradices B1, Rhizophagus intraradices A2 and Funneliformis mosseae in the control of N. aberrans, and to evaluate the physiological and biochemical responses to inoculation in pepper plants. The experiment was conducted under controlled conditions. Mycorrhization percentages, chlorophyll, carotenes, soluble proteins, proline, phenolic compounds, total and reducing sugar content, relative conductivity of root cell membranes and final nematode population were determined. The mycorrhization percentages were higher in plants parasitised by N. aberrans than in those not parasitised. The final population of nematodes was reduced in the presence of mycorrhizae. In the absence of AMF, parasitism by N. aberrans caused a decrease in the soluble proteins and chlorophyll content. The loss of functionality of infected roots in the plants induced water stress, reflected by the accumulation of proline, sugar and increased the relative conductivity of cell membranes. At the same time, as a product of pathogenesis, phenolic compounds accumulated. Inoculation with AMF decreased the proline, sugars, phenolic compounds content and relative conductivity. These results show the potential for the use of AMF in pepper production to reduce the population of N. aberrans, being the strain R. intraradices B1 as the most promising candidate.