Characterization of a new partitivirus strain in Verticillium dahliae provides further evidence of the spread of the highly virulent defoliating pathotype through new introductions

The soilborne pathogen Verticillium dahliae, causal agent of Verticillium wilt, has a worldwide distribution and many hosts of agronomic value. The worldwide spread of a highly virulent defoliating (D) pathotype has greatly increased the threat posed by V. dahliae in olive trees. For effective disease management, it is important to know if the D pathotype is spreading long distances from contaminated material, or if D pathotype isolates may have originated locally from native V. dahliae populations several times. We identified a double-stranded RNA mycovirus in an olive D pathotype isolate from Turkey. Sequencing and phylogenetic analysis clustered the virus with members of the family Partitiviridae. The virus was most similar to a partitivirus previously identified in a V. dahliae isolate from cotton in China (VdPV1), with sequence identities of 94% and 91% at the nucleotide level for RNA1 and RNA2, respectively. The virus therefore corresponded to a strain of the established species, and we designated it VdPV1-ol (VdPV1 from olive). The identification of the same viral species in these two fungal isolates from geographically distant origins provides evidence of their relationships, supporting the hypothesis of long-distance movement of V. dahliae isolates.This research was supported by the Spanish Ministry of Science and Innovation (Grants AGL2009- 13445), and the Junta de Andalucía (Grant FEDER P07-TIC-02682) and AGL2013-48980-R.Peer reviewe

Characterization of a new partitivirus strain in Verticillium dahliae provides further evidence of the spread of the highly virulent defoliating pathotype through new introductions

The soilborne pathogen Verticillium dahliae, causal agent of Verticillium wilt, has a worldwide distribution and many hosts of agronomic value. The worldwide spread of a highly virulent defoliating (D) pathotype has greatly increased the threat posed by V. dahliae in olive trees. For effective disease management, it is important to know if the D pathotype is spreading long distances from contaminated material, or if D pathotype isolates may have originated locally from native V. dahliae populations several times. We identified a double-stranded RNA mycovirus in an olive D pathotype isolate from Turkey. Sequencing and phylogenetic analysis clustered the virus with members of the family Partitiviridae. The virus was most similar to a partitivirus previously identified in a V. dahliae isolate from cotton in China (VdPV1), with sequence identities of 94% and 91% at the nucleotide level for RNA1 and RNA2, respectively. The virus therefore corresponded to a strain of the established species, and we designated it VdPV1-ol (VdPV1 from olive). The identification of the same viral species in these two fungal isolates from geographically distant origins provides evidence of their relationships, supporting the hypothesis of long-distance movement of V. dahliae isolates

Characterization of a new Partitivirus Strain in Verticillium dahliae provides further evidence of the spread of the highly virulent defoliating pathotype through new introductions

Trabajo presentado en el XVII Congreso de la Sociedad Española de Fitopatología, celebrado en Lleida del 7 al 10 de octubre de 2014.The soilborne pathogen Verticillium dahliae, causal agent of Veticillium wilt, has a worldwide distribution and a plethora of hosts of agronomic value. The spread of a highly virulent defoliating (D) pathotype has greatly increased the threat posed by V. dahliae in olive trees. For disease management, it is important to know if the D pathotype is spreading from contaminated material worldwide, or if D isolates may have originated from native V. dahliae populations several times. In this work, we provide evidence to support the hypothesis of long-distance movement of V. dahliae isolates. We identified a double-strand RNA mycovirus in an olive D isolate from Turkey. Sequencing and phylogenetic analysis clustered it with members of the family Partitiviridae. Interestingly, it was most similar to a partitivirus previously identified in a V. dahliae cotton isolate from China (VdPV1), with sequence identities of 94% and 91% at the nucleotide level for RNA1 and RNA2, respectively. It corresponded therefore to a strain of the established species, and we designated it VdPV1-ol (VdPV1 from olive). V. dahliae has been described as an asexually-reproducing fungus in which exchange of genetic material is restricted to isolates in the same vegetative compatibility group. Mycoviruses are among the genetic elements that can be readily exchanged between compatible isolates. The identification of the same viral species in these two geographically distant fungal isolates provides evidence of their relationships. We propose that micoviruses can serve as fingerprints to study geographical flows in V. dahliae.This work was supported by the Spanish Ministry of Science and Innovation (Grant AGL2009-13445), and the Junta de Andalucía (Grant FEDER P07-TIC-02682).N