Lisianthus Leaf Necrosis: A New Disease of Lisianthus Caused by Iris yellow spot virus

Abstract

Unusual viral symptoms were seen on lisianthus (Eustoma russellianum) grown in the Besor area in Israel. Symptoms included necrotic spots and rings on leaves and systemic necrosis. Preliminary analyses suggested that the disease was caused by a tospovirus. Virus particles typical of a tospovirus were observed with electron microscopy in samples taken only from symptomatic leaves. Double-antibody sandwich enzyme-linked immunosorbent assay tests of leaf sap, extracted from lisianthus and mechanically inoculated indicator plants, gave a strong positive reaction to Iris yellow spot virus (IYSV). Polyclonal antibodies prepared against IYSV enabled specific detection of the virus in crude sap from infected plants. Western blot analysis showed that IYSV was serologically distinct from Tomato spotted wilt virus (TSWV). Primers specific to the nucleocapsid gene of IYSV were used in a reverse transcription-polymerase chain reaction assay (RT-PCR) to verify the presence of IYSV. RT-PCR gave an expected PCR product of approximately 850 bp. The sequence of the cloned nucleocapsid gene confirmed the identity of IYSV, thus confirming IYSV infection of lisianthus. This is the first report of IYSV infection in dicotyledons.

Occurrence of iris yellow spot virus from onion crops in Egypt

“…In ultrathin sections of IYSV-Egypt-infected onion leaves, spherical particles were observed within membrane-bound vesicles only in symptomatic tissues of infected plants. Similar results were obtained by Kritzman and Kritzman [20,21]. Plant tissues obtained after IYSV-Egypt transmission with viruliferous thrips gave positive results with the IYSV antiserum (data not shown).…”

Plant Viruses Transmitted by Thrips

“…in Japan (Murai, 2004: Okuda andHanada, 2001;Okuda et al, 2003). Lisianthus is a host of IYSV in Israel (Kritzman et al, 2000(Kritzman et al, , 2001 and Japan (Doi et al, 2003;Murai, 2004). IYSV has since been detected in Clivia minata and Bessera elegans in Japan at one location where astroemeria was infected (M. Okuda, NARC for Kyushu Okinawa, pers.…”

“…IYSV IL was found to have 96% homology with IYSV NL and 91% homology with IYSV BR . IYSV IL was reported to have 99% homology with the Israeli onion strain (Kritzman et al, 2000(Kritzman et al, , 2001. The onion and amaryllis strain of IYSV in Israel have been reported to be serologically identical (Kritzman et al, 2001).…”

Iris yellow spot virus found infecting onions in three Australian states

“…iris (Iris hollandica), lisianthus (Eustoma russellianum) and Hippeastrum sp. IYSV is reported from several countries, including Brazil, USA, Israel and the Netherlands (Cortes et al 1998;Gera et al 1998;Pozzer et al 1999;Kritzman et al 2000). Although its onion thrips (Thrips tabaci) vector is common throughout Australia (Mound and Gillespie 1997), IYSV is not known to occur.…”

“…Likely control measures for onion crops include removing volunteer and wild Allium spp., destroying discard piles, planting transplants from virus-tested nurseries, avoiding all-year-round overlapping plantings and applying insecticides to kill the vector. (Cortes et al 1998), and AF271219 an isolate from Lisianthus from Israel (Kritzman et al 2000).…”