RESUMO
This contribution is part of a series devoted to the phylogeny and taxonomy of powdery mildews, with an emphasis on North American taxa. An overview of Cystotheca species is given, including references to ex-type sequences or, if unavailable, proposals for representative reference sequences for phylogenetic-taxonomic purposes. The new species C. mexicana is described, based on Mexican collections on Quercus glaucoides × Quercus microphylla and Quercus liebmannii × Q. microphylla. Cystotheca lanestris is reported for the first time worldwide on Quercus laceyi (Collected in Mexico) and on Q. toumeyi (collected in Arizona, USA). Cystotheca lanestris on Q. agrifolia and on Q. cerris is reported for the first time in Mexico. Epitypes with ex-epitype sequences are designated for Cystotheca wrightii, Lanomyces tjibodensis (= C. tjibodensis), Sphaerotheca kusanoi, and S. lanestris (C. lanestris).
Assuntos
Quercus , Filogenia , México , ArizonaRESUMO
Translation initiation factor eIF4E exerts an important role during infection of viral species in the family Potyviridae. Particularly, a eIF(iso)4E family member is required for Arabidopsis thaliana susceptibility to Turnip mosaic virus, Lettuce mosaic virus, and Tobacco etch virus (TEV). In addition, a resistance mechanism named restriction of TEV movement (RTM) in A. thaliana controls the systemic spread of TEV in Col-0 ecotype. Here, we describe that TEV-TAMPS, a Mexican isolate, overcomes the RTM resistance mechanism reported for TEV-7DA infection of the Col-0 ecotype but depends on eIF(iso)4E for its systemic spread. To understand at which level eIF(iso)4E participates in A. thaliana TEV-TAMPS infection, the viral RNA replication and translation were measured. The absence or overexpression of eIF(iso)4E did not affect viral translation, and replication was still observed in the absence of eIF(iso)4E. However, the TEV-TAMPS systemic spread was completely abolished in the null mutant. The viral protein genome-linked (VPg) precursor NIa was found in coimmunoprecipitated complexes with both, eIF(iso)4E and eIF4E. However, the viral coat protein (CP) was only present in the eIF(iso)4E complexes. Since both the VPg and the CP proteins are needed for systemic spread, we propose a role of A. thaliana eIF(iso)4E in the movement of TEV-TAMPS within this host.