The unconventional geminivirus Beet curly top Iran virus: satisfying Koch's postulates and determining vector and host range

Abstract

Beet curly top Iran virus (BCTIRV) is a geminivirus with unusual genomic organisation, recently reported in Iran, infecting sugarbeet and a few other plant species. Although three BCTIRV sequences have been reported, demonstration that BCTIRV DNA is the causal agent of the disease was missing. A full-length genomic DNA was obtained from symptomatic leaves of sugarbeet collected in the Sivand area of Iran, and its nucleotide sequence was determined (BCTIRV-Siv, 2845 nt). To satisfy Koch's postulates, an infectivity assay was developed by inserting a 1.4-mer of BCTIRV-Siv DNA in Agrobacterium tumefaciens and using it in agroinoculation experiments. The cloned viral DNA was capable of infecting sugarbeets, reproducing the leaf curling and vein enations observed in the field. These results demonstrate that the single DNA component of BCTIRV is sufficient for infectivity. Host range studies indicated that some economically important crops can be affected, such as spinach, tomato and sweet pepper, as well as important laboratory plants including Nicotiana benthamiana, Arabidopsis thaliana and Jimson weed. Circulifer haematoceps, the dominant leafhopper species present in sugarbeet fields in Iran, was successfully used to transmit the disease. The availability of an infectious clone will facilitate extended host range studies, to determine the potential risks to other crops, as well as genetic studies on this unusual member of the family Geminiviridae.

Establishment of three new genera in the family Geminiviridae: Becurtovirus, Eragrovirus and Turncurtovirus

“…1): 1) Becurtovirus: Including the species Beet curly top Iran virus and Spinach curly top Arizona virus (Table 1) [14,18,19,33,39] 2) Eragrovirus: Including the species Eragrostis curvula streak virus (Table 2) [35] 3) Turncurtovirus: Including the species Turnip curly top virus (Table 3) [5,29,30] We additionally acknowledge the need for further new genera to accommodate three other highly divergent groups of geminiviruses that have recently been found infecting grapevines in the USA [22,28] and citrus plants in Turkey [23], as well as two closely related viruses (*72 % genomewide pairwise sequence identity) infecting Euphorbia caputmedusae in South Africa [4] and French beans in India.…”

Beet curly top virus Strains Associated with Sugar Beet in Idaho, Oregon, and a Western U.S. Collection

“…Viruses in the genus Becurtovirus also infect sugar beet and cause curly top symptoms. These viruses include both Beet curly top Iran virus and Spinach curly top Arizona virus (Gharouni Kardani et al 2013;Hernández-Zepeda et al 2013;Heydarnejad et al 2007Heydarnejad et al , 2013Soleimani et al 2013, Varsani et al 2014b, Yazdi et al 2008.BCTV almost eliminated sugar beet production in the western United States in the 1920s and early 1930s until resistant cultivars were developed (Bennett 1971;Panella et al 2014). Resistant cultivars remain an important control measure; however, most commercial cultivars only contain low to moderate levels of resistance, because the resistance is thought to be quantitatively inherited and is difficult to maintain in parental lines used to create commercial hybrids Kaffka et al 2002;Panella et al 2014;Strausbaugh et al 2007).…”

“…Yield may be affected in important crops such as common bean, pepper, spinach, sugar beet, and tomato (Blickenstaff and Traveller 1979;Chen and Gilbertson 2009;Creamer et al 1996;Soto and Gilbertson 2003;Soto et al 2005). Several distinct, genetically characterized members of the genus Curtovirus have been confirmed as causative agents of curly top in sugar beet (Briddon et al 1998;Gharouni Kardani et al 2013;Heydarnejad et al 2007Heydarnejad et al , 2013Soleimani et al 2013;Stenger 1998;Strausbaugh et al 2008;Yazdi et al 2008). However, reevaluation of the genus Curtovirus assigned most of these viruses formerly recognized as distinct Curtovirus spp.…”

“…Viruses in the genus Becurtovirus also infect sugar beet and cause curly top symptoms. These viruses include both Beet curly top Iran virus and Spinach curly top Arizona virus (Gharouni Kardani et al 2013;Hernández-Zepeda et al 2013;Heydarnejad et al 2007Heydarnejad et al , 2013Soleimani et al 2013, Varsani et al 2014b, Yazdi et al 2008.…”

RNA de interferência como estratégia para controle de begomoviroses

“…de DNA no início do processo replicativo (Yazdi et al, 2008) (Soleimani et al, 2013 (Briddon et al, 2010) (Razavinejad et al, 2013). (Varsani et al, 2014).…”