Natural infection rate of known Tomato chlorosis virus-susceptible hosts and the influence of the host plant on the virus relationship with Bemisia tabaci MEAM1

Authors: ESQUIVEL-FARINA, ARNALDO - Universidade De Sao Paulo; REZENDE, JORGE - Universidade De Sao Paulo; Wintermantel, William - Bill; Hladky, Laura; BAMPI, DAIANA - Universidade De Sao Paulo

Submitted to: Plant Disease
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/23/2020
Publication Date: 4/6/2021
Citation: Esquivel-Farina, A., Rezende, J.A.M., Wintermantel, W.M., Jenkins Hladky, L.L., Bampi, D. 2021. Natural infection rate of known Tomato chlorosis virus-susceptible hosts and the influence of the host plant on the virus relationship with Bemisia tabaci MEAM1. Plant Disease. https://doi.org/10.1094/PDIS-08-20-1642-RE.
DOI: https://doi.org/10.1094/PDIS-08-20-1642-RE

Interpretive Summary: Tomato chlorosis virus (ToCV; genus Crinivirus, family Closteroviridae) was identified in tomato crops in the state of São Paulo, Brazil in 2006. Management strategies to control external sources of inoculum are necessary, because chemical control of the whitefly vector Bemisia tabaci MEAM1 has not efficiently prevented virus infections and no commercial tomato varieties or hybrids are resistant to this crinivirus. We first evaluated the how easily some known wild and cultivated ToCV-susceptible hosts are to natural infection by ToCV and their attractiveness for B. tabaci MEAM1 to lay eggs on these plants. Physalis angulata was the most susceptible to natural infection during six exposures in 2018 and 2019. No plants of bell pepper (var. Dahra) or lambsquarters (Chenopodium album) became infected. It is necessary to correctly identify the potentially important ToCV-susceptible hosts in the vicinity of new plantings in order to minimize or prevent damage from the tomato yellowing disease through management of external sources of ToCV. Only two eggplant (var. Napoli) plants developed infection among 60 exposed. Pepper and lambsquarters plants were the least preferred, and tobacco and eggplant were the most preferred for egg laying by whiteflies. In addition, from 2016 to 2019, we surveyed different tomato crops and the surrounding vegetation to identify ToCV in weeds and cultivated plants in the region of Sumaré, São Paulo state. Only Solanum americanum, S. sisymbriifolium and C. album were found naturally infected, with incidences of 18%, 20% and 1.4%, respectively. Finally, we estimated the amount of ToCV (isolates ToCV-FL, USA and ToCV-SP, Brazil) in different ToCV-susceptible host plants by RT-qPCR and evaluated the relationships among between acquisition, and transmission by B. tabaci MEAM1. The results showed significant differences in ToCV concentrations in the tissues of ToCV-susceptible host plants, which appeared to be influenced by the virus isolate. The concentration of the virus in plant tissues, in turn, directly influenced the ToCV-B. tabaci MEAM1 relationship and subsequent transmission to tomato plants.

Technical Abstract: Tomato chlorosis virus (ToCV; genus Crinivirus, family Closteroviridae) was identified in tomato crops in the state of São Paulo, Brazil in 2006. Management strategies to control external sources of inoculum are necessary, because chemical control of the whitefly vector Bemisia tabaci MEAM1 has not efficiently prevented virus infections and no commercial tomato varieties or hybrids are resistant to this crinivirus. It is necessary to correctly identify potentially important ToCV-susceptible hosts in the vicinity of new plantings in order to minimize or prevent the damage from the tomato yellowing disease through management of external sources of ToCV. Natural infection rates of some known wild and cultivated ToCV-susceptible hosts and their attractiveness for B. tabaci MEAM1 oviposition were evaluated in 2018 and 2019. Physalis angulata was the most susceptible to natural infection in all six exposures. Neither pepper (Capsicum annuum var. Dahra) nor Chenopodium album plants were infected in these tests, but two of 60 eggplant (Solanum melongena var. Napoli) plants exposed in these tests developed infections. Pepper and C. album were the least preferred for whitefly oviposition, while tobacco (Nicotiana tabacum) and eggplant were the most preferred. We surveyed different tomato crops and the surrounding vegetation from 2016 to 2019 in order to identify ToCV in weeds and cultivated plants in the region of Sumaré, São Paulo state. Only Solanum americanum, S. sisymbriifolium and C. album were found naturally infected, with incidences of 18%, 20% and 1.4%, respectively. We estimated the ToCV titer (isolates ToCV-FL, USA and ToCV-SP, Brazil) in different ToCV-susceptible host plants by RT-qPCR and evaluated their relationships with virus acquisition and transmission by B. tabaci MEAM1. There were significant differences in ToCV concentrations in the tissues of ToCV-susceptible host plants, which appeared to be influenced by the virus isolate. The concentration of the virus in plant tissues, in turn, directly influenced the ToCV-B. tabaci MEAM1 relationship and subsequent transmission to tomato plants.