In the present study, transmission trials have been carried out to investigate the possible capability of transmitting Bois noir phytoplasma (BNp) ('Candidatus Phytoplasma solani', subgroup 16SrXII-A) to grapevine of phloem-feeding insect species prevalent in a vineyard in Franciacorta (Lombardy region, North Italy). Specimens of the 10 prevalent BNp-harboring (infection rate ≥20%) insect species (Aphrodes makarovi, Cicadella viridis, Dicranotropis hamata, Dictyophara europaea, Euscelis incisus, Euscelidius variegatus, Hyalesthes obsoletus, Laodelphax striatella, Philaenus spumarius, and Psammotettix alienus) captured at 5 sampling days (June 28; July 06 and 21; August 03 and 24) in 2016 in a BN-affected vineyard in Franciacorta, have been forced to feed on phytoplasma-free grapevine (Chardonnay) plants under controlled conditions. Dead insects were maintained at -30°C. ‘Ca. P. solani’ was detected by nested PCR-based amplification of stamp gene using as templates the total nucleic acids extracted from both the insect specimens and the petioles of grapevine plants collected at October 2016 and July 2017 (plants were kept in insect-free greenhouse for one year).‘Ca. P. solani’ detected in insects and plants were characterized through nucleotide sequence analyses of stamp amplicons. Stamp gene amplification detected ‘Ca. P. solani’ in all the insect species examined and their host grapevine plants (excepted the host plants of C. viridis) sampled in July 2017, one year after the transmission trials. Even if D. hamata and P. spumarius insects utilized in two transmission trials were found uninfected, their host grapevine plants were positive to stamp gene amplification. This can be due to the phytoplasma titer too low for nested PCR-based detection. Only plants hosting E. incisus and E. variegatus were found infected by 'Ca. P. solani' also in October 2016, at the end of the season in which transmission trials were carried out. No amplification was obtained from control plants, kept in controlled conditions without insects. Identity analysis of stamp gene nucleotide sequences evidenced that 'Ca. P. solani' strains, identical to those prevalent in the examined vineyard (St5 and St19), were found in the insect specimens and in the grapevine plant employed in the same transmission trial (excepted A. makarovi and D. hamata). Such results indicated that D. europaea, E. incisus, E. variegatus, L. striatella, P. spumarius, and P. alienus are able to transmit 'Ca. P. solani' to grapevine. To the best of our knowledge, this is the first study reporting these insects as vectors able to transmit 'Ca. P. solani' to adult grapevine plants. Further studies are needed to investigate the transmission efficiency in open field and to study accurately the ecology of such insects.
|Titolo:||New insights on insect vectors transmitting ‘Candidatus Phytoplasma solani’ to grapevine|
|Data di pubblicazione:||set-2018|
|Settore Scientifico Disciplinare:||Settore AGR/12 - Patologia Vegetale|
Settore AGR/11 - Entomologia Generale e Applicata
|Citazione:||New insights on insect vectors transmitting ‘Candidatus Phytoplasma solani’ to grapevine / N. Mori, F. Quaglino, F. Sanna, A. Moussa, M. Faccincani, P.A. Bianco. ((Intervento presentato al 5. convegno Bois Noir tenutosi a Ljubljana nel 2018.|
|Appare nelle tipologie:||14 - Intervento a convegno non pubblicato|