Biodiversity of foliar endophytes in the native grass Poa bonariensis

MC CARGO, P.; IANNONE L.J.; NOVAS, M.V.

Lexington, Kentucky

Congreso; The International Symposium on Fungal Endophytes of Grasses; 2010

Most of the studies on endophytes of grasses have been focused on the systemic vertically/horizontally transmitted epichloë-endophytes. These endophytes have been proved to protect their hosts against pathogens and to suppress fungal growth in culture. However, little is known about the total biodiversity of foliar endophytes of grasses and its relationships with vertically transmitted epichloë-endophytes. In this work we studied the biodiversity of horizontally transmitted endophytes of Poa bonariensis, a perennial grass native to Argentina, and its association with the presence of Neotyphodium endophytes. To achieve this, we randomly collected plants of P. bonariensis without disease symptoms from a natural population that present Neotyphodium infected (E+) and Neotyphodium free (E-) plants. The presence of Neotyphodium was checked in all collected plants, and 20 E+ and 20 E- plants were chosen for biodiversity analyses. Thirty surface-disinfected leaf fragments of each plant were plated on malt extract agar medium. The isolates obtained were subjected to different treatments to induce sporulation. Sporulating isolates were morphologically identified to species level. The  nonsporulating isolates were sorted out into different morphotypes, according to their cultural characteristics, and a random sample from each morphotype was selected for molecular identification based on the ITS sequences. The identification was performed by alignment with sequences from GenBank database using BLAST and phylogenetic analyses with Mr. Bayes 3.1. The abundance and diversity of endophytes between E+ and E- plants was compared using the Shannon diversity index (H). A total of 524 isolates were obtained. Although only isolated from E+ plants, Neotyphodium was the most abundant endophyte in this population, followed by Alternaria, Cladosporium, Drechslera, Stagonospora and Acremonium, other taxa like Curvularia, Paecilomyces, Phoma, Radulidium, Sporormiella and Peniophora were also isolated. E+ plants presented a significantly higher quantity and biodiversity of foliar endophytes in E+ than in E- plants.