Update and New Epidemiological Aspects about Grapevine Yellows in Chile

Abstract

To date, phytoplasmas belonging to six ribosomal subgroups have been detected to infect grapevines in Chile in 36 percent of the sampled plants. A new survey on the presence of grapevine yellows was carried out from 2016 to 2020, and 330 grapevine plants from the most important wine regions of the country were sampled and analyzed by nested PCR/RFLP analyses. Phytoplasmas enclosed in subgroups 16SrIII-J and 16SrVII-A were identified with infection rates of 17% and 2%, respectively. The vineyards in which the phytoplasma-infected plants were detected were further inspected to identify alternative host plants and insects of potential epidemiological relevance. Five previously unreported plant species resulted positive for 16SrIII-J phytoplasma (Rosa spp., Brassica rapa, Erodium spp., Malva spp. and Rubus ulmifolius) and five insect species were fully or partially identified (Amplicephalus ornatus, A. pallidus, A. curtulus, Bergallia sp., Exitianus obscurinervis) as potential vectors of 16SrIII-J phytoplasmas. The 16SrVII-A phytoplasmas were not detected in non-grape plant species nor in insects. This work establishes updated guidelines for the study, management, and prevention of grapevine yellows in Chile, and in other grapevine growing regions of South America.

Detection and identification of a 16SrIII‐J subgroup phytoplasma associated with faba bean in Peru

“…The detection of 16SrIII‐J in symptomatic faba bean samples is the first identification of phytoplasmas enclosed in this ribosomal subgroup in Peru; they were reported first in Brazil (Montano et al., 2000) and later infecting several other crop species in South American states such as Argentina (Fernández et al., 2020; Galdeano et al., 2013), Brazil (Munhoz et al., 2019) and Chile (Quiroga et al., 2020). The identification of variability at the 16Sr level is not unusual in phytoplasmas classified in the 16SrIII group where the frequent presence of interoperon heterogeneity is reported in several strains (Davis et al., 2013).…”

Survey for ‘Candidatus Liberibacter’ and ‘Candidatus Phytoplasma’ in Citrus in Chile

“…Insect vectors can, therefore, sporadically visit crops and transmit phytoplasmas, suggesting that spontaneous vegetation may also be a reservoir for these phytoplasmas [29,44,45]. This situation has been evidenced in epidemiological studies associated with grapevine yellows in Chile [46][47][48].…”

“…The samples were transported in thermoregulated containers and stored at 4 • C before nucleic acid extraction. DNA was extracted from 1 g of midribs using the CTAB method [48]. The nucleic acids were dissolved in Tris-EDTA buffer pH 8.0 and kept at 4 • C. All samples were analyzed by PCR and nested-PCR.…”

Diverse phytoplasmas associated with maize bushy stunt disease in Peru

“…P. asteris' is widely reported to infect corn on the American continent (Lee et al, 2004), this is the first detection of 16SrIII-J phytoplasmas in corn. The 16SrIII-J phytoplasma strain is widespread in other countries of South America such as Brazil (Montano et al, 2000), Argentina (Galdeano et al, 2013) and Chile (Quiroga et al, 2020) where it was detected in several herbaceous and woody horticultural species. Recently it was also identified in faba bean in Peru (Torres-Suarez et al, 2021) and insect vectors of this phytoplasma strain were identified as Paratanus exitiosus (Beamer) and Bergallia valdiviana Berg 1881 in Chile (Quiroga et al, 2019).…”