Archivio Journal of Plant Pathology

Abstract:

Several species and varieties of the family Crassulaceae have been introduced and cultivated for ornamental as well as medicinal purposes in Brazil, more prominently Cotyledon orbiculata (pig’s ear). This work reports the identification and characterization of viruses associated with foliar mosaic and distortion of C. orbiculata from the succulent plant collection of the garden of the University of São Paulo, Brazil. In situ analyses revealed enveloped bacilliform particles in the perinuclear space of infected C. orbiculata cells, and cytoplasmic cylindrical inclusions, typical of the family Potyviridae. Viruses were mechanically transmitted and separated by differential indicator hosts and aphid transmission (Myzus persicae). Chenopodium amaranticolor and Datura stramonium served as differential hosts for the potyvirus and the bacilliform virus, respectively. Positive serological reactions were obtained when leaf extracts from naturally infected C. orbiculata and experimental hosts were exposed to an antiserum to Sonchus yellow net virus (genus Nucleorhabdovirus). Identification of the potyvirus by RT-PCR, cloning into pGEM-T vector and sequencing generated a 1,752 nt fragment corresponding to part of the nuclear inclusion protein b (NIb), the complete coat protein (CP) and the untranslated region (UTR). Amino acid identities below 80% were observed, indicating that the potyvirus of C. orbiculata may be a new species for which the name Cotyledon virus Y (CotVY) is suggested.