Distribution and Transmission of Iris yellow spot virus

Abstract

Iris yellow spot virus (IYSV), a new tospovirus associated with a disease in onion (Allium cepa) that is known to growers in Israel as “straw bleaching,” was identified and further characterized by host range, serology, electron microscopy, and molecular analysis of the nucleocapsid gene. The transmissibility of IYSV by Thrips tabaci and Frankliniella occidentalis was studied. IYSV was efficiently transmitted by T. tabaci from infected to healthy onion seedlings and leaf pieces. Two biotypes of F. occidentalis, collected from two different locations in Israel, failed to transmit the virus. Surveys to relate the incidence of thrips populations to that of IYSV were conducted in onion fields. They revealed that the onion thrips T. tabaci was the predominant thrips species, and that its incidence was strongly related to that of IYSV. Forty-five percent of the thrips population collected from IYSV-infected onion and garlic fields in Israel transmitted the virus. IYSV was not transmitted to onion seedlings from infected mother plants through the seed, and was not located in bulbs of infected plants.

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).…”

Onion Thrips (Thysanoptera: Thripidae): A Global Pest of Increasing Concern in Onion

“…Besides damage to the onion crop, T. tabaci adults and larvae also can feed on ßower pedicels and buds and reduce seed yield in onions grown for seed production (Elmore 1949). In addition to injury by feeding, T. tabaci transmits IYSV and is the only conÞrmed vector of this pathogen (Pozzer et al 1999, Kritzman et al 2001. IYSV was Þrst identiÞed on onion in southern Brazil in 1981 (Pozzer et al 1994) and was conÞrmed in the United States in 1989 in Idaho and Oregon (Hall et al 1993).…”

First report of Iris yellow spot virus in Costa Rica

“…Uncertain diagnosis based on leaf symptoms and discrepancies between ELISA and RT-PCR results were reported previously (Krauthausen et al 2012). Moreover, the distribution of IYSV throughout an infected plant is uneven (Kritzman et al 2001;Smith et al 2006) and thus the pieces of tissue used for ELISA and RT-PCR may contain differential virus titer, even when extracted from the same plant. The low frequency of diamond-shaped lesions (diagnosis-value symptom) may be due to different onion varieties and/or weather conditions (Nischwitz et al 2006(Nischwitz et al , 2007.…”

“…IYSV is transmitted by two species of thrips (Thysanoptera): Thrips tabaci (Kritzman et al 2001) and Frankliniella fusca (Srinivasan et al 2012). Since the first report of the virus in Brazil, it has been reported in numerous countries in Africa, North and South America, Asia, Europe, and Oceania, and since 2003 this tospovirus is associated to disease epidemics in the USA and other countries (reviewed in Pappu et al 2009).…”