Horizontal gene and chromosome transfer in plant pathogenic fungi affecting host range

Abstract

Plant pathogenic fungi adapt quickly to changing environments including overcoming plant disease resistance genes. This is usually achieved by mutations in single effector genes of the pathogens, enabling them to avoid recognition by the host plant. In addition, horizontal gene transfer (HGT) and horizontal chromosome transfer (HCT) provide a means for pathogens to broaden their host range. Recently, several reports have appeared in the literature on HGT, HCT and hybridization between plant pathogenic fungi that affect their host range, including species of Stagonospora/Pyrenophora, Fusarium and Alternaria. Evidence is given that HGT of the ToxA gene from Stagonospora nodorum to Pyrenophora tritici-repentis enabled the latter fungus to cause a serious disease in wheat. A nonpathogenic Fusarium species can become pathogenic on tomato by HCT of a pathogenicity chromosome from Fusarium oxysporum f.sp lycopersici, a well-known pathogen of tomato. Similarly, Alternaria species can broaden their host range by HCT of a single chromosome carrying a cluster of genes encoding host-specific toxins that enabled them to become pathogenic on new hosts such as apple, Japanese pear, strawberry and tomato, respectively. The mechanisms HGT and HCT and their impact on potential emergence of fungal plant pathogens adapted to new host plants will be discussed.

Unveiling the biosynthetic puzzle of destruxins in Metarhizium species

“…Thus, the lateral acquisition of the dtxS1 gene cluster could have driven, at least in part, the evolution of Metarhizium generalist species able to kill multiple orders of insects. In support of this interpretation, several ribosomal and nonribosomal toxins involved in virulence are believed to have been transferred by horizontal gene transfer (HGT) between plant pathogenic fungi (40). For example, interspecific transfer of a host-selective toxin gene (toxA) from the wheat pathogen Stagonospora nodorum to Pyrenophora triticirepentis enabled the latter to cause a serious disease in wheat (41).…”

Computational Analysis Reveals Industrial Natural Products and Toxins in Charcoal Rot Pathogen, <i>Macrophomina phaseolina</i>

“…On an evolutionary scale, diversity is introduced into polyketides through gene flow, genetic recombination and mutation, i.e. both simple mutations within the domains and frequent horizontal co-transfer of genes between clusters 49 . Generation of novelty through exchange of domains between biosynthetic gene clusters polished under evolutionary selection pressure, invariably results in successful product assembly -as millions of failed experiments were rapidly discarded by natural selection.…”

Widespread horizontal transfer of the cerato-ulmin gene between Ophiostoma novo-ulmi and Geosmithia species

“…Formation of transient hyphal or conidial anastomoses, direct uptake of DNA, presence of mobile elements in the vicinity of the transferred sequence and recombination have been proposed (Mehrabi et al 2011;Richards et al 2011;Fitzpatrick 2012). Richards et al (2009) showed that in two gene transfers from a fungus to the bryophyte moss Physcomitrella patens, the HGT was located near to a putative transposable element.…”

“…Most documented cases involve the transfer of bacterial genes to unicellular eukaryotes where they have been proposed to play a role in adaptation processes (Andersson et al 2003;Gojkovic et al 2004;Ricard et al 2006;Bowler et al 2008;Sch€ onknecht et al 2013), but the transfer of genes from viral, bacterial or eukaryotic donors to plants and animals has also been described (reviewed in Keeling & Palmer 2008;Bock 2010;Dunning Hotopp 2011). In filamentous fungi, in particular, HGT has been demonstrated in several instances and is involved in the acquirement of important characters such as virulence, leading in some cases to the emergence of new pathogens or of new host specificities for existing ones (Oliver & Solomon 2008;Mehrabi et al 2011;Gardiner et al 2013). This is the case for the fungus Pyrenophora tritici-repentis whose ability to infect wheat has been related to the transfer of the gene encoding the host-selective toxin ToxA from the wheat pathogen Stagonospora nodorum (Friesen et al 2006).…”