Population Diversity and Genetic Structure Reveal Patterns of Host Association and Anthropogenic Impact for the Globally Important Fungal Tree Pathogen Ceratocystis manginecans.

Feifei Liu,Tuan A Duong,Shuaifei Chen,Irene Barnes,Michael J Wingfield

doi:10.3390/jof7090759

Feifei Liu, Tuan A Duong + Show 3 more

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https://doi.org/10.3390/jof7090759

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Abstract

Species in the Ceratocystis manginecans complex are important fungal pathogens of plantation trees globally. The most important hosts include species of Eucalyptus, Acacia, Mangifera, and Punica. Despite their relevance and widespread occurrence, little is known regarding their population genetics and how this might relate to their host associations or geographic regions in which they occur. A global collection of 491 isolates representing the C. manginecans complex, from four different plant hosts and nine countries, were genotyped using microsatellite markers. Population genetic analyses using numerous tools were conducted to interrogate how their genetic diversity and structure might be affected by host or areas of occurrence. Results of genetic diversity studies showed that when grouping isolates into populations based on their host associations, the population on Eucalyptus was most diverse, and it also has a broad global distribution. When considering countries of origin as a basis for defining populations, the gene and genotypic diversity were highest in populations from China, Indonesia, and Brazil. In contrast, populations from Oman and Pakistan collected from Mangifera had the lowest genetic diversity and were clonal. Molecular variance, population differentiation, and network and structure analyses showed that the genetic structure of isolates in the C. manginecans complex is influenced by both host association as well as geographical isolation. Furthermore, the results reflected the movement of genotypes between plant hosts and geographic regions that have implications regarding the broad global distribution of this pathogen.

Highlights

Additional isolates were obtained from the Culture Collection (CMW) of the Forestry and Agricultural Biotechnology Institute (FABI), and these were from Eucalyptus spp. and Acacia spp. from several countries (Brazil, Congo, Indonesia, Malaysia, South Africa, and Uruguay), which were collected and used in previous studies [27,29] (Figure 1; Tables S1 and S2)
Based on the multi-gene phylogenetic analyses, 491 isolates were assigned to the C. manginecans complex, which included isolates that have previously been labeled as either C. manginecans or C. eucalypticola
The results showed that the population on Eucalyptus was the most diverse, having a broad global distribution

Summary

Introduction

Tree diseases caused by fungal pathogens are increasing in incidence and impact globally. This is especially true in the case of trees grown for plantation forestry and fruit tree production [1,2,3,4]. Planted forests and orchards of fruit trees are typically comprised of genetically uniform monocultures, which makes them prone to serious damage by pathogens [9,10,11]. It is important to understand the origins, distribution, and introduction pathways of these tree pathogens in order to manage the real or potential economic impact [3,14,15]

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