Three-Locus Sequence Identification and Differential Tebuconazole Sensitivity Suggest Novel Fusarium equiseti Haplotype from Trinidad.

Ria T Villafana,Sephra N Rampersad

doi:10.3390/pathogens9030175

Abstract

The Fusarium incarnatum-equiseti species complex (FIESC) consists of 33 phylogenetic species according to multi-locus sequence typing (MLST) and Genealogical Concordance Phylogenetic Species Recognition (GCPSR). A multi-locus dataset consisting of nucleotide sequences of the translation elongation factor (EF-1α), calmodulin (CAM), partial RNA polymerase largest subunit (RPB1), and partial RNA polymerase second largest subunit (RPB2), was generated to distinguish among phylogenetic species within the FIESC isolates infecting bell pepper in Trinidad. Three phylogenetic species belonged to the Incarnatum clade (FIESC-15, FIESC-16, and FIESC-26), and one species belonged to the Equiseti clade (FIESC-14). Specific MLST types were sensitive to 10 µg/mL of tebuconazole fungicide as a discriminatory dose. The EC50 values were significantly different among the four MLST groups, which were separated into two homogeneous groups: FIESC-26a and FIESC-14a, demonstrating the “sensitive” azole phenotype and FIESC-15a and FIESC-16a as the “less sensitive” azole phenotype. CYP51C sequences of the Trinidad isolates, although under positive selection, were without any signatures of recombination, were highly conserved, and were not correlated with these azole phenotypes. CYP51C sequences were unable to resolve the FIESC isolates as phylogenetic inference indicated polytomic branching for these sequences. This data is important to different research communities, including those studying Fusarium phytopathology, mycotoxins, and public health impacts.

Highlights

Bell pepper (Capsicum annuum L.) is one of the most widely cultivated vegetable crops in the world
The three-locus dataset consisted of concatenated EF-1α, CAM, and RPB2 partial gene sequences based on their demonstrated phylogenetic informativeness within the genus
The remaining Trinidad isolates belonged to the Incarnatum clade as phylogenetic species Fusarium incarnatum-equiseti species complex (FIESC)-15a (22%), FIESC-16a (48%), and FIESC-26a (22%) and these sequences were resolved for each individual locus

Summary

Introduction

Bell pepper (Capsicum annuum L.) is one of the most widely cultivated vegetable crops in the world. The world’s production and consumption of bell peppers have been steadily increasing. More than 70% of the world’s bell peppers are produced in Asia, with China being the largest producer of bell peppers [1]. The Fusarium disease of bell pepper, resulting in external fruit rot, is caused by F. oxysporum, F. proliferatum, F. solani, F. lactis, and F. incarnatum-equiseti species complexes and has been reported to occur in Belgium, Canada, the Netherlands, and the United. Symptoms of external infection include water-soaked, sunken lesions that expand to or originate from the calyx end of the fruit—either in the ripe or immature green stage. Internal fruit rot can develop where the seeds and placenta become infected and turn black with rot

Objectives

Methods

Results

Conclusion