Molecular and biological characterization of Chilli leaf curl virus and associated Tomato leaf curl betasatellite infecting tobacco in Oman

Abstract

BackgroundIn Oman tobacco (Nicotiana tabacum; family Solanaceae) is a minor crop, which is produced only for local consumption. In 2015, tobacco plants exhibiting severe downward leaf curling, leaf thickening, vein swelling, yellowing and stunting were identified in fields of tobacco in Suhar Al-Batina region, Oman. These symptoms are suggestive of begomovirus (genus Begomovirus, family Geminiviridae) infection.MethodsCircular DNA molecules were amplified from total DNA extracted from tobacco plants by rolling circle amplification (RCA). Viral genomes were cloned from RCA products by restriction digestion and betasatellites were cloned by PCR amplification from RCA product, using universal primers. The sequences of full-length clones were obtained by Sanger sequencing and primer walking. Constructs for the infectivity of virus and betasatellite were produced and introduced into plants by Agrobacterium-mediated inoculation.ResultsThe full-length sequences of 3 begomovirus and 3 betasatellite clones, isolated from 3 plants, were obtained. Analysis of the full-length sequences determined showed the virus to be a variant of Chilli leaf curl virus (ChiLCV) and the betasatellite to be a variant of Tomato leaf curl betasatellite (ToLCB). Both the virus and the betasatellite isolated from tobacco show the greatest levels of sequence identity to isolates of ChiLCV and ToLCB identified in other hosts in Oman. Additionally clones of ChiLCV and ToLCB were shown, by Agrobacterium-mediated inoculation, to be infectious to 3 Nicotiana species, including N. tabacum. In N. benthamiana the betasatellite was shown to change the upward leaf rolling symptoms to a severe downward leaf curl, as is typical for many monopartite begomoviruses with betasatellites.ConclusionsThe leaf curl disease of tobacco in Oman was shown to be caused by ChiLCV and ToLCB. This is the first identification of ChiLCV with ToLCB infecting tobacco. The study shows that, despite the low diversity of begomoviruses and betasatellites in Oman, the extant viruses/betasatellites are able to fill the niches that present themselves.

Analysis of Pathogenicity and Virulence Factors of Ageratum leaf curl Sichuan virus

“…Previous data revealed that betasatellites can be trans-replicated by several different begomovirus, and trans-replication by a true monopartite begomovirus can potentially lead to the formation of new disease complexes in plants co-infected with other begomoviruses, thereby causing more serious symptoms ( Qing and Zhou, 2009 ). Moreover, betasatellites play important roles in determining begomovirus host ranges and, hence, could lead to the emergence of serious disease in many crops ( Jing et al., 2016 ; Gnanasekaran et al., 2019 ; Shahid et al., 2019 ). In this study, we found that co-inoculating ALCScV with noncognate DNA β induced more severe symptoms and increased the accumulation of ALCScV.…”

Molecular diagnosis of begomovirus associated with Chilli leaf curl disease in Jeddah, Saudi Arabia

“…So far, only a few begomoviruses in the Kingdom such as TYLCV and ToLCSDV causing disease in Tomato, Cucumber, Sponge gourd, Squash, Mentha, Corchorus, Amaranthus, and Okra have been reported ( Idris et al, 2012 , Idris et al, 2014 , Al-Saleh et al, 2014 , Sohrab, 2016 , 2017a , 2017b , Sohrab, 2020 , Sohrab et al, 2016 , Sohrab and Daur, 2018a , 2018b ). The Association of ChiLCV and betasatellite infecting crops has been reported from Oman ( Khan et al, 2013 , Shahid et al, 2019 ). The introduction of begomovirus causing disease in the different crops in the kingdom has been introduced from the surrounding countries.…”

“…The cultivation of Chilli is severely affected by many diseases caused by multiple pathogens including viruses, fungus, bacteria and nematodes. The Chilli leaf curl disease (ChiLCD) caused by a begomovirus known as Chilli leaf curl virus (ChiLCV) is an important limiting factor for Chilli cultivation worldwide ( Shahid et al, 2019 ). Based on the current literature review, a total of sixty-five viruses are known to cause diseases in chilli crops ( Thakur et al, 2018 ).…”

“…Many isolates of begomovirus and associated satellites have been reported globally infecting Chilli ( Khan and Khan, 2017 ). The begomovirus causing ChiLCD to multiple crops has been identified and from the neighboring country, Oman ( Khan et al, 2013 , Shahid et al, 2019 ).…”

“…As per the current status and published reports; the information about the natural infection of the begomovirus on Chilli crop is lacking from the kingdom of Saudi Arabia. So far, viral diseases including begomovirus on various crops have been identified from the Arabian region and neighboring countries like; Nile Basin, Oman, Yemen, and Iran ( Al-Shahwan et al, 1997 , Ghanem et al, 2003 , Ajlan et al, 2007 , Idris et al, 2012 , Idris et al, 2014 , Khan et al, 2013 , Hosseinzadeh et al, 2014 , Al-Saleh et al, 2014 , Sohrab, 2016 , Khan and Khan, 2017 , Shahid et al, 2019 ). The begomovirus and their associated satellites infecting other crops like Amaranthus, Beans, Cucurbits, Corchorus, Mentha, Tomato and weeds have been identified earlier from the Arabian region ( Al-Shahwan et al, 1997 , Ghanem et al, 2003 , Ajlan et al, 2007 , Idris et al, 2012 , Idris et al, 2014 , Hosseinzadeh et al, 2014 , Al-Saleh et al, 2014 , Sohrab, 2016 , 2017a , 2017b , Sohrab, 2020 , Sohrab et al, 2016 , Sohrab and Daur, 2018a , 2018b ).…”