The foliar fungal endophytes of Citrus limon in Argentina

Abstract

Fungal endophytes associated with Citrus limon (L.) Burm., were investigated. Culture of surface-sterilized leaves from two orchards of lemon trees in Tucumán, located in northwestern Argentina, revealed the presence of endophytic fungi in all leaves examined. The colonization frequencies were 69.7% and 72.3% at the two sampled sites, and a total of nine taxa were isolated. Eight of the taxa had relative frequencies of >2% in at least one sample. The number of isolates was significantly lower in the spring. The assemblage composition at each site and sampling time was similar. Colletotrichum gloeosporioides (Penz.) Penz. & Sacc. in Penz., responsible for anthracnose, was consistently dominant. Another pathogenic fungus of Citrus spp., Guignardia citricarpa Kiely was also recovered as an endophyte. Scanning electron micrographs of cut uncultured and cultured leaf surfaces, seen in transverse section, showed intercellular fungal hyphae in parenchyma cells No penetration of host cells by either fungus was observed. This is the first report on fungal endophytes in leaves of lemon plants in Argentina.Key words: endophytic fungi, lemon, colonization, scanning electron microscopy.