Origanum vulgare L. (family Lamiaceae) is a perennial herbaceous species, originating from Mediterranean regions and Asia, widely cultivated as culinary herb and for therapeutic purposes. During spring-summer 2009, 3-4% of potted plants, randomly distributed in protected nurseries of Albenga area (Liguria region), were noted to be stunted and showing a bright yellow leaf mosaic (“calico” type). Mother-plants growing in the same nurseries for cutting production were symptomless. Preliminary electron microscopy observations of leaf-dips prepared from symptomatic and asymptomatic plants, revealed the presence of bacilliform virus-like particles in only symptomatic samples. Symptoms observed on herbaceous hosts mechanically inoculated with crude sap of a single affected plant (isolate Orv-1), were: chloro-necrotic lesions in Chenopodium murale, Beta vulgaris, Phaseolus vulgaris and Vigna unguiculata; systemic mosaic in Capsicum annuum and Nicotiana benthamiana; systemic mosaic and necrotic line-patterns in N. tabacum “Samsun”. The virus was serologically identified as an isolate of Alfalfa mosaic virus (AMV) by applying DAS-ELISA technique and molecularly using AMV-specific oligonucleotides pair, designed to retrotrascribe and amplify the coat protein (CP) gene. Restriction profile obtained after BamHI digestion of the putative CP gene amplicon, identified Orv-1 as an AMV subgroup I isolate (Parrella et al., 2000). A large set of oligonucleotides were used to amplify and sequence the whole RNA3 segment. Sequence analysis revealed that Orv-1 RNA3 was 2038 nucleotides in length, containing two open reading frames (ORFs) identified by sequence comparisons as coding the putative movement proteins (MP) and the CP. The first ORF consisted of 867 residues, coding for the 31 kDa putative MP, the second consisted of 657 residues, coding for the 24 kDa putative CP. Orv-1 RNA3 showed the highest percentage of identity with the RNA3 of the 425 Madison isolate (Acc. n. K02703) also belonging to AMV subgroup I. Phylogenetic relationships of Orv-1 isolate with members of AMV subgroups I and II, clearly showed that both CP and MP nucleotide sequences of this O. vulgare isolate clustered within the subgroup I, confirming preliminary results obtained by restriction analysis of the CP gene. Further works are in progress in order to sequence the entire genome of the Orv-1 AMV isolate. Although AMV was already reported to infect O. vulgare, first in Argentina (Feldman and Gracia, 1977) and then in New Zealand (Fletcher, 1987), to our knowledge this is the first record of AMV infecting this aromatic plant in Italy. This finding confirms an increasing diffusion of AMV in Liguria region, especially in aromatic crops.

FIRST FINDING AND MOLECULAR CHARACTERIZATION OF ALFALFA MOSAIC VIRUS INFECTING ORIGANUM VULGARE IN ITALY

CAVICCHI, LISA;BELLARDI, MARIA GRAZIA
2010

Abstract

Origanum vulgare L. (family Lamiaceae) is a perennial herbaceous species, originating from Mediterranean regions and Asia, widely cultivated as culinary herb and for therapeutic purposes. During spring-summer 2009, 3-4% of potted plants, randomly distributed in protected nurseries of Albenga area (Liguria region), were noted to be stunted and showing a bright yellow leaf mosaic (“calico” type). Mother-plants growing in the same nurseries for cutting production were symptomless. Preliminary electron microscopy observations of leaf-dips prepared from symptomatic and asymptomatic plants, revealed the presence of bacilliform virus-like particles in only symptomatic samples. Symptoms observed on herbaceous hosts mechanically inoculated with crude sap of a single affected plant (isolate Orv-1), were: chloro-necrotic lesions in Chenopodium murale, Beta vulgaris, Phaseolus vulgaris and Vigna unguiculata; systemic mosaic in Capsicum annuum and Nicotiana benthamiana; systemic mosaic and necrotic line-patterns in N. tabacum “Samsun”. The virus was serologically identified as an isolate of Alfalfa mosaic virus (AMV) by applying DAS-ELISA technique and molecularly using AMV-specific oligonucleotides pair, designed to retrotrascribe and amplify the coat protein (CP) gene. Restriction profile obtained after BamHI digestion of the putative CP gene amplicon, identified Orv-1 as an AMV subgroup I isolate (Parrella et al., 2000). A large set of oligonucleotides were used to amplify and sequence the whole RNA3 segment. Sequence analysis revealed that Orv-1 RNA3 was 2038 nucleotides in length, containing two open reading frames (ORFs) identified by sequence comparisons as coding the putative movement proteins (MP) and the CP. The first ORF consisted of 867 residues, coding for the 31 kDa putative MP, the second consisted of 657 residues, coding for the 24 kDa putative CP. Orv-1 RNA3 showed the highest percentage of identity with the RNA3 of the 425 Madison isolate (Acc. n. K02703) also belonging to AMV subgroup I. Phylogenetic relationships of Orv-1 isolate with members of AMV subgroups I and II, clearly showed that both CP and MP nucleotide sequences of this O. vulgare isolate clustered within the subgroup I, confirming preliminary results obtained by restriction analysis of the CP gene. Further works are in progress in order to sequence the entire genome of the Orv-1 AMV isolate. Although AMV was already reported to infect O. vulgare, first in Argentina (Feldman and Gracia, 1977) and then in New Zealand (Fletcher, 1987), to our knowledge this is the first record of AMV infecting this aromatic plant in Italy. This finding confirms an increasing diffusion of AMV in Liguria region, especially in aromatic crops.
2010
Congresso SiPAV
266
267
G. Parrella; A.G. Nappo; L. Cavicchi; M.G. Bellardi
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11585/90386
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