Identification and pathogenicity of Diplodia seriata and Diplodia africana related to lentisk dieback in Tunisia

Abstract

Lentisk dieback has been commonly observed in Tunisian forests. Nevertheless, the identity of the parasitic factors involved in this phenomenon has not yet been reported. Thus, in order to characterize the dieback-associated agents, symptomatic branches were collected from Pistacia lentiscus in the Rimel forest (Northern Tunisia). Two Botryosphaeriaceae species, Diplodia seriata and D. africana, were isolated and identified firstly based on morphological characteristics. Then, molecular identification was performed by sequencing the internal transcribed spacer region (ITS1-5.8S-ITS4), a part of the translation elongation factor 1-α (EF1-α) gene and a partial sequence of the β-tubulin (TUB) gene. The two species were morphologically and phylogenetically distinct from all Diplodia species and represent newly recorded fungal pathogens of lentisk in Tunisia. Pathogenicity tests carried out on asymptomatic detached branches confirmed the virulence of the two species. These findings may confirm D. seriata and D. africana as fungal pathogens associated with lentisk dieback in Tunisia.