CONTRIBUTION OF ARBUSCULAR MYCORRHIZAL SYMBIOSIS TO ALLEVIATE STRESS CAUSED BY NACOBBUS ABERRANS NEMATODE

GARITA, SEBASTIAN; RIPODAS, JUAN IGNACIO; RUSCITTI, MARCELA; ARANGO, MARIA CECILIA; BERNARDO, VALERIA

Congreso; XV Spanish Portuguese congress of plant physiology; 2017

Nacobbus aberrans is a parasitic root-knot nematode that causes yield losses in horticultural crops across theAmericas, even leading to the death of plants in the case of severe attacks. The products currently used for its controlhave a high economic cost, lack specificity and have a high degree of toxicity. Symbiosis with arbuscular mycorrhizalfungi (AMF) has been shown to have a protective effect against several soil pathogens. Plants of Solanum lycopersicumCv. Platense both with and without mycorrhizal colonization by Funneliformis mosseae were cultivated in soilartificially inoculated and not inoculated with N. aberrans. Four months after the transplant, the plants were extractedand it could be observed that the mobile forms of N. aberrans had penetrated into the roots, destroying the corticalparenchyma, causing necrotic lesions, barking of the root and the death of rootlets. As a consequence of this damage incell membranes, malondialdehyde levels were significantly higher (1.9 nmoles.g-1) in comparison to tests treatmentswhere the pathogen was absent (1.2 nmoles.g1). In mycorrhizal plants, the number of lesions was significantly lowerthan in non-mycorrhizal plants. Adult females were hosted by the roots forming galls, breaking the continuity ofconductive tissues and altering the normal flow of water. As a consequence, infected plants suffered water stress,leading to an increase in proline levels (? 50%), and a reduction of protein content (? 20%). In mycorrhizal plants,water stress indicators had significantly lower values than in non-mycorrhizal plants. In addition, the number ofnematode eggs collected in mycorrhizal roots was 80% lower than in non-mycorrhizal plants, indicating that thispractice is beneficial to both attenuating the stress caused by the pathogen and reducing its population.