Use of arbuscular mycorrhizae for phytoparasitic nematodes control and growth promotion in pepper plants

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

San Carlos de Bariloche

Simposio; II International Symposium Mycorrhizal Symbiosis in South America; 2019

COMAHUE

The rosary?s nematode Nacobbus aberrans affects plant growth and development and decreases the production of numerous horticultural crops. Several investigations have shown that vesicular-arbuscular mycorrhizae could confer tolerance to pathogens through different mechanisms of action, as mycoparasitism, competition of space for nutrients, and induction of plant resistance. The objective of this work was to analyze the potential of two strains of mycorrhizal fungus (AMF) Rhizophagus intraradices in the control of Nacobbus aberrans and to evaluate the response to inoculation in pepper plants. The assay was performed under controlled conditions. Plants were inoculated at sowing with two strains of R. intraradices, B1 and A2. Three days after transplant (DDT) pepper plants were inoculated in half of the pots with 5000 N. aberrans´s eggs. At 90 DDT, the percentage of mycorrhization, chlorophyll and soluble proteins content, proline, phenolic compounds, total sugars content, root electrical conductivity and number of total eggs of the nematode were determined. The percentage of mycorrhization was 49% and 38%, for B1 and A2, respectively. The number of eggs was reduced 93% and 86% in the plants inoculated with B1 and A2 respectively, compared to the non-inoculated ones. The penetration of mobile forms of N. aberrans in the roots produced damages in the cell membranes that caused the electrolytes liberation, increasing the relative conductivity of the cell membranes without inoculating (24.26%) with respect to the inoculated ones (13 ,6%). In the absence of mycorrhizal fungi, parasitism by N. aberrans caused a decrease in the content of soluble proteins and chlorophyll, with respect to plants without parasitizing. The loss of the functionality of the infected roots in the plants induced a water stress, reflected by the accumulation of proline and total sugars, osmolytes used by plants in stress situations. At the same time, as a product of pathogenesis, phenolic compounds were accumulated. Both in plants parasitized and not parasitized by the nematode, the inoculation with mycorrhizal fungi, increased the soluble proteins and chlorophyll content, and decreased the proline, sugars and phenolic compounds contents. These results show the potential for the use of AMF in horticultural crops, both to reduce the population of N. aberrans as to promote the plant growth in situation of biotic stress.