Phylogenetic species recognition and hybridisation in Lasiodiplodia : A case study on species from baobabs

Abstract

Lasiodiplodia species (Botryosphaeriaceae, Ascomycota) infect a wide range of typically woody plants on which they are associated with many different disease symptoms. In this study, we determined the identity of Lasiodiplodia isolates obtained from baobab (Adansonia species) trees in Africa and reviewed the molecular markers used to describe Lasiodiplodia species. Publicly available and newly produced sequence data for some of the type strains of Lasiodiplodia species showed incongruence amongst phylogenies of five nuclear loci. We conclude that several of the previously described Lasiodiplodia species are hybrids of other species. Isolates from baobab trees in Africa included nine species of Lasiodiplodia and two hybrid species. Inoculation trials with the most common Lasiodiplodia species collected from these trees produced significant lesions on young baobab trees. There was also variation in aggressiveness amongst isolates from the same species. The apparently widespread tendency of Lasiodiplodia species to hybridise demands that phylogenies from multiple loci (more than two and preferably four or more) are compared for congruence prior to new species being described. This will avoid hybrids being incorrectly described as new taxa, as has clearly occurred in the past.

Botryosphaeriaceae species causing dieback on Annonaceae in Brazil

“…(Abdollahzadeh et al, 2010). This fungus was also found in Bougainvillea spectabilis in China (Li et al, 2015), Adansonia digitata in Benin, Cameroon, Madagascar, Mozambique, Senegal and South Africa (Cruywagen et al, 2017), among others. In Brazil, this species was one of the most prevalent in the northeastern region, associated with stem-end rot on mango trees (Marques et al, 2013a), and it was reported causing dieback on Anacardium sp.…”

“…This disease has repeatedly been associated with the Botryosphaeriaceae fungus, Lasiodiplodia theobromae (Ponte, 1985;Lopez, 2005;Junqueira & Junqueira, 2014). However, more detailed studies need to be conducted to accurately identify the causal agents of this disease because the genus Lasiodiplodia is known to comprise complexes of species (Alves et al, 2008;Cruywagen et al, 2017).…”

Invasive Everywhere? Phylogeographic Analysis of the Globally Distributed Tree Pathogen Lasiodiplodia theobromae

“…We excluded cryptic lineages based on previous studies that have resolved the taxonomy of Lasiodiplodia spp. and have defined these lineages as distinct species, including hybrid species [12,27]. As such, the current collection represents a valuable resource to represent a sensu stricto definition of the species.…”

“…For PCR amplifications, the primer sets ITS1 and ITS4 [32], EF1F and EF2R [33], EF688F and EF1251R [34], Bt-2a and Bt-2b [35], and RPB2-LasF and RPB2-LasR [27] were used to amplify the ITS, tef1α, tub2, and rpb2 loci, respectively. PCR mixes were the same as those that included KAPA Taq and MyTaq DNA polymerases as described by Mehl et al [36] and PCR cycling conditions and product visualization were the same as those used by Mehl et al [37].…”

Endophytic Botryosphaeriaceae, including five new species, associated with mangrove trees in South Africa

“…A total of four partial gene regions, the Internal Transcribed spacer regions 1 and 2, including the 5.8S nrRNA gene (ITS), the beta-tubulin tub2), the translation elongation factor 1-alpha (tef1-α) and the DNA-directed RNA polymerase II second largest subunit (rpb2) regions were amplified using the polymerase chain reaction (PCR). Standard published primers were utilized for each region, including BT2a, BT2b (Glass and Donaldson 1995), ITS1, ITS4 (White et al 1990), EF1F, EF2R (Jacobs et al 2004) and/or EF1-688F, EF1-1251R , rpb2bot6F, rpb2bot7R (Sakalidis 2004) and/or rpb2lasF, rpb2lasR (Cruywagen et al 2016).…”