Phylogenetic Characterization of Botryosphaeria Strains Associated with Asphondylia Galls on Species of Lamiaceae

Abstract

In the last decade, Botryosphaeria dothidea has been steadily reported as an associate of gall midges (Diptera, Cecidomyiidae) in a variety of host plants and ecological settings. This cosmopolitan fungus is well-known for its ability to colonize many plant species, as both a pathogen and an endophyte. Thus, the shift from this general habit to a lifestyle involving a strict symbiotic relationship with an insect introduces expectancy for possible strain specialization which could reflect separated phylogenetic lineages. Considering the recent taxonomic revision concerning species of Botryosphaeria, we evaluated the phylogenetic relationships among strains recovered from Asphondylia galls collected on several species of Lamiaceae in Poland and in Italy, and all the currently accepted species in this genus. A number of strains previously characterized from gall samples from Australia and South Africa, whose genetic marker sequences are deposited in GenBank, were also included in the analysis. As a result, full identity as B. dothidea is confirmed for our isolates, while strains from the southern hemisphere grouped separately, indicating the existence of genetic variation related to the geographic origin in the association with gall midges.

New Cladosporium Species from Normal and Galled Flowers of Lamiaceae

“…In fact, symbiotic associations generally involve specific adaptations by the symbionts which are considered to characterize single or closely related taxa. Confirming this assumption, B. dothidea is now regarded as the fungal associate of these midges after some controversies occurred in the past which in most instances derived from nomenclatural reassessments [ 25 , 26 ]. This evidence obviously contrasts the hypothesis that Cladosporium may have a role in this peculiar biological association.…”

“…In the course of a cooperative investigational activity on the fungal associates developing in galls produced by midges of the genus Asphondylia in flowers of several species of Lamiaceae [ 23 , 24 ], strains of Cladosporium were frequently recovered during the isolation attempts. However, unlike Botryosphaeria dothidea which was only isolated from galls [ 25 ], Cladosporium isolates were also obtained from the inner parts of normal flowers and from achenes, indicating that their presence in the flower microenvironment is independent by the insect, and is likely to not affect flower physiology. In the absence of previous assessments, identification at species level appeared to be fundamental in order to conclusively establish whether these isolates are taxonomically homogeneous, hence, to be possibly regarded as specialized gall associates, or rather occur as unrelated saprophytes.…”

Endophytic Fungi of Olive Tree

“…Unlike the above pathogens, the agent of the Dalmatian disease of olives, Botryosphaeria dothidea [ 65 ], is missing in the list of endophytic fungi, despite this species is best known as an endophyte of a high number of plants [ 66 ]. The fact that its documented occurrence is restricted to diseased drupes is possibly linked to the role as a vector by the cecidomyid Lasioptera berlesiana , a parasitoid of the olive fruit fly Bactrocera oleae [ 67 ], considering that B. dothidea is constantly associated with many cecidomyid midges [ 68 ].…”

Taxonomical Study of Noteworthy Species of Botryosphaeria in Japan

“…Moreover, symbiotic relationships among the host plants, insects inhabiting the gall, and Botryosphaeria spp. have been discovered [8][9][10].…”