Abstract
Fungal plant pathogens pose a significant threat to biodiversity and food security worldwide. This threat is aggravated by their rapidly evolving genomes that adapt to evade host plant defenses, reducing the efficacy of deployed resistant crops. Magnaporthe oryzae infects rice, wheat, and many other grasses, resulting in significant crop losses each year. Transposable elements (TEs) are hypothesized to be involved in the evolution and rapid adaptation of M. oryzae. However, there is still much to understand about how these elements behave in different M. oryzae host-specific lineages. In this study, we completed the annotation and phylogenetic classification of TEs in five lineages of M. oryzae. We identified differences in TE content between these lineages, and showed that recent lineage-specific expansions of certain TEs have contributed to greater TE content in rice-infecting and Setaria-infecting lineages. We reconstructed the histories of LTR-retrotransposon expansions and found them to have experienced complex dynamics, where some were caused by the proliferation of one element, while others consisted of multiple elements from an older population of TEs that proliferated in parallel. Additionally, we found evidence suggesting the recent transfer of a DNA transposon between rice and wheat M. oryzae lineages, and a region showing evidence of recombination between those lineages, which could have facilitated such a transfer. These results point towards key differences in TE dynamics, evolutionary history, and adaptive potential between the rice-and-Setaria-infecting and the wheat-Lolium-and-Eleusine-infecting lineage groups.
Competing Interest Statement
The authors have declared no competing interest.
