Effects of arbuscular mycorrhizal fungi on the phytophagous nematode Nacobbus aberrans in plants with agricultural importance

MARRO, NICOLÁS

Pruhonice

Seminario; Mycorrhiza Department Seminars; 2019

Mycorrhiza department - Institute of Botany - CAS

Nacobbus aberrans is a sedentary endoparasite that causes histological alterations tothe root tissues and produces severe damage to crops of agricultural importance. Thearbuscular mycorrhizal fungi (AMF) establish a symbiotic relationship with most plantspecies through chemical communication mediated by components of radical exudates;among them, the plant hormone strigolactone (SL) plays an important role. The AMFincrease host tolerance to different stress factors and the attack of soil pathogens, such as,plant-parasitic nematodes. In the search for management methods of N. aberrans, the use ofAMF is a promising option to minimize the damage induced by this pest. So far,information on their interaction with AMF is limited. The aim of this work was to evaluatethe use of AMF as an alternative of biological control of N. aberrans in agriculturallyimportant vegetables and to study possible mechanisms involved in that relationship. Onthe one hand, the effect of the individual and combined inoculation of two species of AMF(Rhizophagus intraradices and Funneliformis mosseae) on the parasite in tomato (Solanumlycopersicum) and pepper (Capsicum annuum) was examined. After 60 days, the plantdevelopment (total biomass, aerial and root length), the percentage of arbuscularmycorrhizal colonization (% AMC) and nematode variables [number of galls, egg massesand reproduction factor (RF)] were measured. On the other hand, it was analyzed how theprevious mycorrhization (singular and dual) of tomato affected the penetration level ofjuveniles of the nematode in the root systems. The aerial length showed no differencesbetween treatments, while the root length decreased in the presence of N. aberrans, even inmycorrhized roots. In infected plants, the main beneficial effect on biomass was obtainedby combining AMF. In the two hosts, the % AMC was higher in the presence of thenematode while the number of galls, egg masses, RF and the level of penetration of theparasite (in tomato experience) decreased independently of the mode of inoculation ofAMF. Besides, the relative gene expression of SL in the nematode-AMF-tomato interactionwas quantified and measured, showing that was significantly higher in pre-mycorrhizedplants and inoculated with N. aberrans. In addition, it was observed that when applying twodifferent initial densities of the nematode, SL production increased while gene expressionwas higher only with the highest inoculum. The results of this work show that theindividual and combined use of AMF had similar action on the population of the parasite; however, inoculating them together favored plant growth. It is evident that one of thepossible mechanisms involved in the nematode-AMF-plant interaction would be theproduction of SL. Due to the antagonistic effect of AMF on N. aberrans, it is important tostudy the combined use of different species of fungi as biological control agents in plants ofagricultural importance for the country.