A Phytoplasma Closely Related to the Pigeon Pea Witches'-Broom Phytoplasma (16Sr IX) Is Associated with Citrus Huanglongbing Symptoms in the State of São Paulo, Brazil

Abstract

In February 2007, sweet orange trees with characteristic symptoms of huanglongbing (HLB) were encountered in a region of São Paulo state (SPs) hitherto free of HLB. These trees tested negative for the three liberibacter species associated with HLB. A polymerase chain reaction (PCR) product from symptomatic fruit columella DNA amplifications with universal primers fD1/rP1 was cloned and sequenced. The corresponding agent was found to have highest 16S rDNA sequence identity (99%) with the pigeon pea witches'-broom phytoplasma of group 16Sr IX. Sequences of PCR products obtained with phytoplasma 16S rDNA primer pairs fU5/rU3, fU5/P7 confirm these results. With two primers D7f2/D7r2 designed based on the 16S rDNA sequence of the cloned DNA fragment, positive amplifications were obtained from more than one hundred samples including symptomatic fruits and blotchy mottle leaves. Samples positive for phytoplasmas were negative for liberibacters, except for four samples, which were positive for both the phytoplasma and 'Candidatus Liberibacter asiaticus'. The phytoplasma was detected by electron microscopy in the sieve tubes of midribs from symptomatic leaves. These results show that a phytoplasma of group IX is associated with citrus HLB symptoms in northern, central, and southern SPs. This phytoplasma has very probably been transmitted to citrus from an external source of inoculum, but the putative insect vector is not yet known.

Detection and molecular characterisation of a group 16SrIX phytoplasma infecting citrus (Citrus sinensis and C. limon), coffee (Coffea arabica), periwinkle (Catharanthus roseus), and tabebuia (Tabebuia heterophylla) in Puerto Rico

“…Similarly, using direct and nested PCR assays, the presence of phytoplasmas was confirmed for most symptomatic sweet orange samples showing severe blotchy and mottling of leaves. Our findings agree with reports from Brazil, where 89 % of symptomatic sweet orange trees examined from 16 municipalities in the state of São Paulo were positive for phytoplasmas belonging to 16SrIX-PPWB group (Teixeira et al 2008). Similar results were also reported from Citrus spp.…”

“…In tropical areas, periwinkle plants may serve as a natural reservoir for this pathogen, spreading the disease to other plant species of economic importance, such as citrus trees (Barbosa et al 2012), although we did not observe on symptomatic periwinkle plants leafhoppers that could be potential insect vectors. Circumstantial evidence suggests that PPWB phytoplasma in several plant species has emerged as a significant problem in South and Central America (Kenyon et al 1998;Teixeira et al 2008), and this microorganism can be spread to neighbouring countries. However, these perceptions may be a result of the recent increase of PPWB cases worldwide, and can be attributed, in many instances, to the infection of other microorganisms (such as virus, bacteria and spiroplasmas) different from phytoplasmas (Chen et al 2008).…”

“…Furthermore, in a region of São Paulo, Brazil, orange trees (Citrus sinensis) with HLB characteristic symptoms, were negative for infection by three 'Ca. Liberibacter' species, but were found positive for a phytoplasma highly related with PPWB phytoplasma of group 16SrIX (Teixeira et al 2008). These findings make it necessary to investigate the identity, symptomatology, vector association, host range, and impact of diseases of unknown etiology in crops of economic importance in Puerto Rico.…”

“…These plants species included citrus (Teixeira et al 2008), Gliricidia sepium (Kenyon et al 1998), phlox (Madhupriya and Khurana 2013), toria oilseed (Azadvar et al 2009) and periwinkle (Barros TSL 2009). These findings suggest that the host range for this microorganism is very broad, causing similar symptoms in different plant species.…”

Levantamento populacional de cigarrinhas (Hemiptera: Cicadellidae) associadas à transmissão de Xylella fastidiosa em pomares cítricos do Litoral Norte da Bahia

“…Assim, o conhecimento das cigarrinhas desse grupo também é importante, pois caso ocorra a introdução deste patógeno, os aspectos epidemiológicos relacionados à sua transmissão serão mais facilmente compreendidos. Recentemente, detectou-se a presença de um fi toplasma associado a uma doença com sintomas semelhante ao greening (ou huanglongbing) em plantas cítricas no estado de São Paulo (Teixeira et al 2008), sendo as cigarrinhas da subfamília Deltocephalinae e os psilídeos os potenciais vetores desse patógeno. Além de Scaphytopius sp., deltocefalíneos do gênero Bahita também ocorreram em números signifi cativos em armadilhas adesivas de uma das áreas avaliadas na Bahia.…”