Changes in the Copy Number of Class II Transposons in Fusarium oxysporum f. Sp. Radicis-cucumerinum Strain V03-2g and Its Derivatives with Broadened Phytopathogenicity

Abstract

© 2019 Kazan Federal University. All Rights Reserved. Phytopathogenic strains of Fusarium oxysporum can parasitize on more than 120 species of crops and ornamental plants posing a serious danger to world agriculture. The wide range of hosts can be evidence of fast changes in the genomes of F. oxysporum strains, thereby allowing them to invade new plant species. Since the sexual reproduction has not been shown yet for F. oxysporum, in both natural and laboratory conditions, the activity of transposable elements can be responsible for the fast evolution of host specificity in this species. This paper describes the changes in the number of class II transposons in the F. oxysporum f. sp. radicis-cucumerinum (Forc) strain V03-2g, pathogenic to cucumber and its derivatives, which developed pathogenicity towards tomato. Nine transposons of class II (Mimp1, Mimp2, Hornet1, Hornet2, Hornet3, Han, Marsu, Fot3, and Fot4) were followed using qPCR in the wild-type strain V03-2g and its derivatives. The results of the study demonstrate an increase in the copy number of all the studied transposons in the strain V03-2g maintained by the regular plating on laboratory media in a period of one year in comparison with the same strain kept frozen at –80 °C. A decrease of the transposon copy number has been observed in two isolates, SB1 and SB2. In the SB3 isolates, the copy number of transposons increased. The data obtained demonstrate that changes in the transposon copy number can occur under different conditions relatively in a short time and can be the basis for the variability of F. oxysporum strains.