Endophyte isolations from Syzygium cordatum and a Eucalyptus clone (Myrtaceae) reveal new host and geographical reports for the Mycosphaerellaceae and Teratosphaeriaceae

Abstract

Species of Mycosphaerellaceae and Teratosphaeriaceae (Ascomycetes) cause important leaf, shoot and canker diseases globally on a broad range of hosts, including Eucalyptus and other Myrtaceae. Recently, species of the Mycosphaerellaceae and Teratosphaeriaceae have been isolated as asymptomatic endophytes. In this study, endophytic species of Mycosphaerellaceae and Teratosphaeriaceae were isolated from samples taken from healthy native Syzygium cordatum (Myrtaceae) and related non-native Eucalyptus grandis x E. camaldulensis (hybrid clone) growing in Mtubatuba, KwaZulu Natal, South Africa. Multi-locus sequence analysis (MLSA) using the Internal Transcribed Spacer (ITS) region, the partial Large Subunit (LSU; 28S nrDNA) of the nuclear ribosomal DNA operon and Translation Elongation Factor-1α (TEF-1α) genes were used to correctly identify the 22 resulting isolates. The isolates grouped in five clades representing Readeriella considenianae that was isolated only from the Eucalyptus hybrid clone, Mycosphaerella marksii and M. vietnamensis from S. cordatum and Pseudocercospora crystallina from both S. cordatum and the Eucalyptus hybrid clone. Interestingly, the serious canker pathogen T. zuluensis was isolated from Eucalyptus leaves, although it is known only from stem and branch cankers. Of the species found, R. considenianae and M. vietnamensis were found in South Africa for the first time, while M. marksii, M. vietnamensis and P. crystallina were shown to naturally infect native S. cordatum for the first time. Despite the limited number of trees sampled, the new host and distribution reports show that more intensive sampling, especially following an endophyte approach, will reveal more complete patterns of host preference and geographical distribution for these fungi.