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BackgroundPassion fruit woodiness may be caused by Cowpea aphid-borne mosaic virus (CABMV) and is currently the major passion fruit disease in Brazil. To assess the virus-vector-host interactions, a newly introduced golden passion fruit plantation located in eastern region of São Paulo State, Brazil, was monitored.MethodsDissemination of CABMV was determined analyzing golden passion fruit plants monthly for 18 months by PTA-ELISA. Seasonality and aphid fauna diversity was determined by identification of the captured species using yellow sticky, yellow water-pan and green tile traps. Population composition of the aphid species was determined using the descriptive index of occurrence, dominance and general classification and overlap of species in the R program.ResultsAnalyses of species grouping afforded to recognize 14 aphid species. The genus Aphis represented 55.42 % of the species captured. Aphid species formed two distinct clusters, one of which was characterized by the diversity of polyphagous species that presented high potential to spread CABMV.ConclusionThe low abundance and diversity of aphid species did not interfere negatively in the CABMV epidemiology. The genus Aphis, particularly Aphis fabae/solanella and A. gossypii, was crucial in the spread of CABMV in passion fruit orchards in the eastern State of São Paulo.

Figure 1Figure 2 (Ciuffo et al., 2009;Hassani-Mehraban et al., 2010;Oliveira et al., 2011).

To date, seven species of viroids have been described infecting Citrus. However, only Citrus exocortis viroid (CEVd), Hop stunt viroid (HSVd) and Citrus dwarfing viroid (CDVd) have been reported in this crop in Brazil. The aim of our work was to identify and characterize viroids infecting plants of 'Navelina ISA 315' sweet orange cultivar grafted on 'Rangpur' lime from field experiments located in Bebedouro, SP, that showed gumming in the bark and wood symptoms. Biological indexing was done on the indicator host 'Clemelin 1120' tangor plants that reacted with typical gumming symptoms. Viroid infection was assessed by graft-inoculation of buds from the field trees on 'Etrog' citron plants grafted on 'Rangpur' lime, followed by RNA extraction and sPAGE analysis. RNAs were subjected to RT-PCR with primers for citrus viroids. The full-length amplified products were sequenced and compared to those available in the GenBank. The trees were found to be infected with cachexia (Ca) variants of HSVd-Ca or HSVd-Ca plus CDVd. The results indicate that efforts have to be made to increase and stimulate the indexing programs, to maintain plants healthy and to develop sanitary programs focused on reducing the spread of viroids and other graft-transmissible agents.

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