Transmission, In Planta Distribution, and Management of Hibiscus latent Fort Pierce virus, a Novel Tobamovirus Isolated from Florida Hibiscus

A new tobamovirus species has been recently isolated from hibiscus (Hibiscus rosa-sinensis) in Florida (1). This Florida hibiscus virus has been given the name Hibiscus latent Fort Pierce virus (HLFPV) to reflect the site (Fort Pierce, FL) and host (hibiscus) from which it was originally isolated. A limited survey has revealed that this virus is widespread in hibiscus and related species in the Florida landscape (1). Hibiscus plants are common ornamentals in Florida and other subtropical and tropical areas. They are widely used for hedges due to their dense growth and attractive flowers. Hibiscus is vegetatively propagated by cuttings in warm climates and shipped to different regions for indoor and outdoor use (17). This horticultural practice is also a very effective method for virus transmission and dissemination. Cuttings from virus-infected stock plants lead to the production and ultimately dissemination of more infected plants. Several methods for detection of HLFPV have been compared and tested for usefulness in hibiscus stock plant indexing to reduce the propagation of plants infected with HLFPV (16). Because HLFPV is a newly recognized virus of hibiscus, little information is available regarding its transmission during vegetative propagation and pruning, or its overall distribution in infected plants. In general, viruses spread by two paths in infected plants: (i) cell-to-cell through the plasmodesmata and (ii) long-distance through the vascular tissues (15). Based upon the results of his experiments with Tobacco mosaic virus (TMV) in tomato, Samuel suggested that viruses follow certain routes of movement in plants (21). He demonstrated that from the initial place of infection, TMV moved first to the roots, and then to the young, apical leaves before infecting the middle-aged and older leaves. Although it is often assumed that viruses that systemically infect plant hosts eventually become evenly distributed throughout the plant, this rarely happens (15). For many viruses infecting woody perennials, including Plum pox virus (PPV), Tomato ringspot virus (ToRSV), Citrus ringspot virus (CRSV), Apple chlorotic leaf spot virus (ACLSV), and Prunus necrotic ringspot virus (PNRSV), erratic and irregular distribution patterns have been observed (2,4,7,11,20,22). In the present report, three aspects of HLFPV infection of hibiscus were studied: (i) the efficiency of rub-, slash-, and cutinoculation methods for its transmission to two commercial hibiscus cultivars; (ii) the general pattern of virus distribution and accumulation within infected plants; and (iii) the ability of different treatments to prevent transmission with contaminated tools during plant propagation and pruning. Results of these studies reveal several features of the pathosystem that will ultimately guide management strategies.