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Front. Plant Sci. | doi: 10.3389/fpls.2019.01069

Genetic diversity in FUB genes of Fusarium oxysporum f. sp. cubense suggest horizontal gene transfer

  • 1Shenyang Agricultural University, China
  • 2Institute of Fruit Tree Research, Guangdong Academy of Agricultural Sciences (IFTR, GDAAS), China
  • 3Nanjing Agricultural University, China

Fusaric acid (FA) is an important secondary metabolite of many Fusarium species and involved in the wilt symptoms caused in banana by Fusarium oxysporum f. sp. cubense (Foc). To investigate the evolution characteristics of the 12 Foc FA biosynthetic genes (FUB), coding sequences of the 12 FUB genes and 3 housekeeping genes, EF-1α/RPB1/RPB2 (translation elongation factor-1α/RNA polymerase II subunit I/RNA polymerase II subunit II), were subjected to genetic diversity analysis, phylogenetic analysis, recombination detection and selective pressure analysis. The results of selective pressure analysis showed that the 15 genes were mainly subjected to negative selection. However, significantly higher number of silent mutations, which could not be simply explained by selective pressure difference, was observed in the 12 FUB genes in Foc than in the three housekeeping genes. Infraspecies phylogeny and recombination detection analysis showed that significantly more horizontal gene transfer (HGT) events (normalized) had occurred in the FUB genes than in the three housekeeping genes. In addition, many of these events involved outgroup isolates and significantly increased the genetic diversity of FUB genes in Foc. The infraspecies phylogenetic analysis suggested that the polyphyletic phylogeny proposed for Foc requires further discussion, and the divergence of race 1, race 4 and the common ancestor of several Fusarium oxysporum (Fo) isolates pathogenic to nonbanana plants should have diverged over a short period. Finally, our results suggest that the FUB genes in Fo should have benefited from HGT to gain a relatively high genetic diversity to respond to different host plants and environments despite mainly being subject to negative selection.

Keywords: Panama disease, Fusarium oxysporumf.sp. cubense, Fusaric acid (FA), horizontal gene transfer, phylogeny, genetic diversity

Received: 27 Sep 2018; Accepted: 07 Aug 2019.

Edited by:

Miguel Dita, Brazilian Agricultural Research Corporation (EMBRAPA), Brazil

Reviewed by:

Harold Meijer, Wageningen University & Research, Netherlands
Gerda Fourie, University of Pretoria, South Africa  

Copyright: © 2019 Liu, Wu, Shen, Li, Ganjun, Li and Guo. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

* Correspondence: Dr. Chunyu Li, Institute of Fruit Tree Research, Guangdong Academy of Agricultural Sciences (IFTR, GDAAS), Guangzhou, 14069007, Guangdong Province, China, lichunyu881@163.com