ABSTRACT
Bois noir (BN) is the most widespread disease of the grapevine yellows complex in the Euro-Mediterranean area. BN is caused by 'Candidatus Phytoplasma solani' (BNp), transmitted from herbaceous plants to grapevine by polyphagous insect vectors. In this study, genetic diversity among BNp strains and their prevalence and possible association with grapevine symptom severity were investigated in a Sangiovese clone organic vineyard in the Chianti Classico area (Tuscany). Field surveys over 2 years revealed a range of symptom severity on grapevine and an increase of BN incidence. A TaqMan allelic discrimination assay detected only tufB type b among BNp strains, suggesting the prevalence of the bindweed-related ecology. Nucleotide sequence analyses of vmp1 and stamp genes identified 12 vmp1 and 16 stamp sequence variants, showing an overall positive selection for such genes. The prevalent genotype was Vm43/St10, reported for the first time in this study and closely related to strains identified only in the French Eastern Pyrenees. BNp strains identified in the examined vineyard and mostly grouped in separate bindweed-related phylogenetic clusters showed statistically significant differences in their distribution in grapevines exhibiting distinct symptom severity. These results suggest the possible occurrence of a range of virulence within BNp strain populations in the Chianti Classico area.
Subject(s)
Phytoplasma/classification , Plant Diseases/microbiology , Vitis/microbiology , DNA, Bacterial/genetics , DNA, Bacterial/metabolism , Italy , Molecular Typing , Phylogeny , Phytoplasma/geneticsABSTRACT
KEYWORDS: antiviral agents; chemotherapy; polyamidoamine; multivalency.
Subject(s)
Antiviral Agents/pharmacology , Mycophenolic Acid/analogs & derivatives , Mycophenolic Acid/pharmacology , Plant Viruses/drug effects , Animals , Cells, Cultured , Dose-Response Relationship, Drug , Mycophenolic Acid/chemistry , Nicotiana/cytology , Nicotiana/virologyABSTRACT
Electrophysiological techniques were applied to investigate the action of antiviral drugs during trans-plasma events in in vivo grapevine cells infected by GLRaV-1 and GLRaV-3. Carbon fiber microelectrodes and redox-sensitive dyes were used to measure trans-plasma membrane electron transport (t-PMET) activity in healthy and infected samples treated with ribavirin, tiazofurin and oseltamivir. Each drug caused a reduction in oxidation current (expressed as Δ[Fe(2+)]) in healthy samples, indicating t-PMET inhibition. In almost all infected samples, the effect of drugs on t-PMET activity was significantly lower, suggesting that higher content of NADH in infected plants can interfere with t-PMET inhibition caused by drugs. Moreover, virus-infected samples exhibited elevated t-PMET activity compared to healthy samples. Analogous effects were observed by dye tests. Considering the effects of drugs on trans-plasma membrane potential, tests showed the activity of a proton pump during drug treatments with no significant difference with regard to health status.
Subject(s)
Antiviral Agents/pharmacology , Electron Transport/drug effects , Membrane Transport Proteins/metabolism , Plant Proteins/antagonists & inhibitors , Enzyme Activation/drug effects , Membrane Potentials/drug effects , Oseltamivir/pharmacology , Oxidation-Reduction/drug effects , Oxidoreductases/metabolism , Plant Proteins/metabolism , Ribavirin/analogs & derivatives , Ribavirin/pharmacology , VitisABSTRACT
KEYWORDS: virus sanitation; in vitro explants; antiviral mechanism; virus longevity.
