Cambios en la comunidad de hongos endófitos cultivables de la cactácea Pilosocereus royenii infestados por Hypogeococcus pungens

Abstract

In Puerto Rico, the communities of columnar cacti such as Pilosocereus royenii are being devastated by the infestation of Hypogeococcus pungens. Chemical control with insecticides is not a viable alternative because the insect takes refuge in the deformed plant tissue and cover itself with a protective wax. Beneficial endophytic fungi have an important role within their host plant, providing defense against biotic and abiotic factors, through the production of bioactive compounds. Bioactive compounds increase plant defenses and/or their ability to attack pathogenic organisms. The purpose of this work was to study the community of endophytic fungi associated with P. royenii and to establish its possible role in the survival of the cactus infested with H. pungens. We assessed 648 fragments (sections) of plant tissue from six individual cacti, three of these free from the symptomatology associated with H. pungens and three affected by the insect. The rate of fungal infection was calculated for individuals of P. royenii, the frequency of fungal morphotypes isolated from plant tissue and the similarity of the fungal community among the individuals we studied. Asymptomatic P. royenii individuals presented a fungal infection rate similar to the individuals affected by H. pungens. A total of 95 colonies were isolated from P. royenii tissue, 50 from asymptomatic individuals and 45 of the affected individuals. From 34 fungal morphotypes present, nine were identified in the genera Cladosporium, Curvularia, Nigrospora and Aspergillus. Infested individuals harbored a fungal community with greater similarity to each other compared to the asymptomatic individuals.