The Passion fruit woodiness virus (

The Passion fruit woodiness virus (PWV) is the most frequently found virus in passion fruit vines in Brazil. Incidences of 71.8% and 73.1 % have been found in commercial crops in the states of São Paulo and Ceará, respectively (Gioria et al., 2000; Lima et al., 1996). PWV causes serious damages in passion fruit vines in all producing regions, reducing leaf area, decreasing productivity, yielding fruit without commercial value and reducing the economical lifespan of the orchard (Rezende, 1994; Gioria et al., 2000).
PWV is a species of the genus Potyvirus, family Potyviridae, whith particles of 670 to 750 nm in length and 12 to 15 nm in diameter, containing positive, single-stranded RNA and producing characteristic, pinwheel-shaped, lamellar inclusions in the cytoplasm of infected cells (Van Regenmortel et al., 2000; Taylor & Greber, 1973). Aphids are the vector of PWV in the field, especially the species Myzus persicae Sulz. and Aphis gossypii Glover (Chagas et al., 1981), with a non-persistent type of virus-vector relationship (Taylor & Greber, 1973). The virus is not transmitted through fruit seeds.


Although PWV was first found in Brazil at the end of the 1970's (Yamashiro & Chagas, 1979), no research effort has been carried out to develop permanent measures for fruit woodiness control. Several suggestions have been done, based on work developed abroad, but have not been effectively applied. Selection of resistant and/or tolerant plants, pre-immunization with mild strains of the virus and the adoption of cultural practices that could minimize the incidence and dissemination of the disease are some of these suggestions (Kitajima et al., 1986; Rezende, 1994; Gioria et al., 2000).

In Australia, control of passion fruit woodiness has succeeded especially with the use of purple and yellow passion fruit hybrids, which are tolerant to the disease (Taylor & Greber, 1973). In some cases, control has been achieved with the utilization of tolerant hybrids, pre-immunized with mild PWV strains (Peasley & Fitzell, 1981), after pioneer research conducted by Simmonds (1959). In Taiwan, the annual eradication of affected plantings and replanting with PWV-free seedlings is the usual procedure (Chang et al., 1992).

Pre-immunization with mild strains of a virus which do not significantly affect development and yield and protect plants against infection and/or manifestation of severe strains of the same virus, is an ecologically sound control alternative for plant viral diseases. In Brazil, this technology has been utilized quite successfully for over three decades, for the control of citrus tristeza (Citrus tristeza virus - CTV) (Müller & Costa, 1968; Müller & Carvalho, 2001). It has also been proved to be efficient for control of mosaic caused by the Papaya ringspot virus – type W (PRSV-W) in some cucurbit species (Rezende et al., 1994; Rezende & Pacheco, 1998; Rezende et al., 1999; Dias & Rezende, 2000).

More recently, a mild strain of the Zucchini yellow mosaic virus (ZYMV), selected by Rabelo (2002), efficiently protected zucchini squash plants against infection by severe strains of ZYMV. This author also demonstrated that the double pre-immunization was efficient for the control of PRSV-W and ZYMV in zucchini squash. Other examples of pre-immunization efficiency for plant viral disease control worldwide can be found in the review by Rezende & Müller (1995).

This research aimed to select mild PWV strains that could be utilized to control passion fruit woodiness virus by pre-immunization.