Lasiodiplodia: Generic revision by providing molecular markers, geographical distribution and haplotype diversity

Lasiodiplodia (Botryosphaeriaceae, Botryosphaeriales) has a global distribution and occurs on a wide range of monocotyledonous, dicotyledonous, and gymnospermous hosts. Most Lasiodiplodia species are pathogens that cause various diseases, such as stem cankers, stem and branch gummosis, shoot blight, and fruit rot. In addition, Lasiodiplodia species occur as endophytes and saprobes. This study presents one of the most reliable molecular markers for Lasiodiplodia. The combination of four loci, the internal transcribed spacer region (ITS), the partial translation elongation factor 1-a gene (tef1-a), beta-tubulin (tub2), and RNA polymerase II second largest subunit (rpb2), provided a more reliable resolution for this genus at the species level. Geographical studies showed that Lasiodiplodia species are distributed in tropical and temperate regions, but not in the polar regions. Among its species, L. theobromae has a worldwide distribution on a wide range of hosts, including economically important crops. Combining the morphology and molecular phylogeny is necessary for accurate taxonomic identification of Lasiodiplodia species and is being used in this study. Multigene phylogenetic analyses were performed based on maximum likelihood and Bayesian inference analyses using combined ITS, tef1-a, tub2, and rpb2 sequence data. In addition, the main morphological characteristics of holotype specimens of Lasiodiplodia species are provided. The current study introduced 25 new host and geographical records of saprobic Lasiodiplodia species from Taiwan province, China and Thailand. Based on the herbarium study, two Lasiodiplodia species, L. avicenniarum and L. krabiensis are synonymized under L. brasiliensis. Our analyses revelaed that Lasiodiplodia theobromae as the most common species in this genus, which occurs in a wide range of hosts in tropical and subtropical regions. The present study has led to the expansion of the taxonomic framework of Lasiodiplodia by revealing new host and geographical records. Furthermore, the haplotype networks generated using ITS, tef1-a, tub2, and rpb2 sequence data for 520 isolates of L. theobromae from 44 host families and 35 countries display that none of the L. theobromae isolates grouped according to their host family or country, suggesting that L. theobromae is a less genetically diverse, globally distributed species.

Automated summary

Lasiodiplodia is a globally distributed pathogen that causes various diseases on a wide range of hosts. This study presents a reliable molecular marker for accurate taxonomic identification of Lasiodiplodia species. Geographical studies show that Lasiodiplodia is distributed in tropical and temperate regions. Lasiodiplodia theobromae is the most common species in this genus and has a wide distribution in tropical and subtropical regions.