Tomato yellow leaf curl virus (TYLCV-IL): a seed-transmissible geminivirus in tomatoes

Abstract

Tomato yellow leaf curl virus (TYLCV) is one of the most well-known tomato-infecting begomoviruses and transmitted by Bemisia tabaci. Seed transmission has previously been reported for some RNA viruses, but TYLCV has not previously been described as a seed-borne virus. In 2013 and 2014, without whitefly-mediated transmission, TYLCV was detected in young tomato plants germinated from fallen fruits produced from TYLCV-infected tomato plants in the previous cultivation season. In addition, TYLCV-Israel (TYLCV-IL) was also detected in seeds and their seedlings of TYLCV-infected tomato plants that were infected by both viruliferous whitefly-mediated transmission and agro-inoculation. The seed infectivity was 20–100%, respectively, and the average transmission rate to seedlings was also 84.62% and 80.77%, respectively. TYLCV-tolerant tomatoes also produced TYLCV-infected seeds, but the amount of viral genome was less than seen in TYLCV-susceptible tomato plants. When tomato plants germinated from TYLCV-infected seeds, non-viruliferous whiteflies and healthy tomato plants were placed in an insect cage together, TYLCV was detected from whiteflies as well as receiver tomato plants six weeks later. Taken together, TYLCV-IL can be transmitted via seeds, and tomato plants germinated from TYLCV-infected seeds can be an inoculum source of TYLCV. This is the first report about TYLCV seed transmission in tomato.

Ongoing geographical spread of Tomato yellow leaf curl virus

“…Although there is no evidence of any movements to East Asia from the Mediterranean basin since 1995, at least five movements of TYLCV into the American/Caribbean region have occurred since the year 2000, suggesting that the flow of TYLCV variants into the Americas from elsewhere in the world is likely ongoing. The recent discovery that at least some TYLCV-IL variants are likely seed-transmissible (Kil et al, 2016) should be seriously investigated as a potential contributor to these movements. In this regard it would be of great interest to compare the seed transmission potential of all the main TYLCV lineages so as to determine whether a potentially causal association exists between the seed-transmissibility of particular lineages and their geographical ranges.…”

“…The global dissemination of TYLCV-Mld and TYLCV-IL from the Middle East or the Eastern Mediterranean (Duffy and Holmes, 2007;Lefeuvre et al, 2010) is attributed to the movement of infected planting material (Seal et al, 2006), together with spread of the Middle East-Asia Minor (MEAM1 formally referred to as the B biotype) and the Mediterranean (MED formally referred to as the Q biotype) cryptic species of its whitefly vector, Bemisia tabaci (Czosnek et al, 2002;Diaz-Pendon et al, 2010;Horowitz et al, 2007;Seal et al, 2006). Recent reports suggest that TYLCV is possibly unique amongst begomoviruses in that it is capable of both replicating within B. tabaci (Pakkianathan et al (2015), as well as being seed transmitted in tomato (Kil et al, 2016). These characteristics may have contributed to it achieving a geographical range that is far broader than those of almost all other begomovirus species.…”

Tomato yellow leaf curl virus: Diagnosis and metabolites

“…TYLCV is transmitted by whiteflies and can spread rapidly; it is also not transmitted through seed or by mechanical transmission. Severe symptoms such as leaf curling, stunting, and yellowing showed on TYLCVinfected tomato plants, which cause serious production loss in tomato cultivation (Kil et al, 2016;Papayiannis et al, 2010). In addition to tomato, other cultivated plants including pepper (Capsicum species), common bean (Phaseolus vulgaris), cucurbit (Cucumis species) and eustoma (Eustoma grandiflora) have been reported to be TYLCV hosts (Anfoka et al, 2009;Kil et al, 2016).…”

“…Severe symptoms such as leaf curling, stunting, and yellowing showed on TYLCVinfected tomato plants, which cause serious production loss in tomato cultivation (Kil et al, 2016;Papayiannis et al, 2010). In addition to tomato, other cultivated plants including pepper (Capsicum species), common bean (Phaseolus vulgaris), cucurbit (Cucumis species) and eustoma (Eustoma grandiflora) have been reported to be TYLCV hosts (Anfoka et al, 2009;Kil et al, 2016). Polymerase chain reaction (PCR) was applied to detect and establish provisional identity of begomoviruses through amplification of 575 bp fragment of the begomoviral coat protein gene (CP), referred to as the 'core' region of the CP gene (core CP).…”

Infectivity of Tomato yellow leaf curl virus isolated from imported tomato fruit in Estonia

“…The rapid global spread of TYLCV is the result of international movement of virus-infected plant material and of plants (including non-hosts of TYLCV) harbouring viruliferous whiteflies (EFSA PLH, 2014). Recently, TYLCV has also been reported to be seed transmitted with high seed transmission rates from infected tomato plants (Kil et al, 2016).…”