Analysis of watermelon chlorotic stunt virus and tomato leaf curl Palampur virus mixed and pseudo-recombination infections

Abstract

Watermelon chlorotic stunt virus (WmCSV) and tomato leaf curl Palampur virus (ToLCPMV) are limiting factors for cucurbit production in south and southeastern Iran. ToLCPMV infects all cucurbit crops (except watermelons) whereas WmCSV is somewhat limited to watermelon, causing detrimental effects on fruit production. In a survey, we detected WmCSV in all watermelon growing farms in Fars province (southern Iran). Given that WmCSV and ToLCPMV are present in the same geographical location in Iran, we studied the interaction of two viruses. Co-infection using agroinfectious clones of WmCSV and ToLCPMV caused severe symptoms in watermelon and zucchini in comparison to symptoms observed from individual infections. Interestingly, inoculation of zucchini with WmCSV DNA-A and ToLCPMV DNA-B agroinfectious clones or vice versa produced a viable pseudo-recombinant and induced systemic symptoms. This demonstrates that replication-associated protein of DNA-A of each virus is able to bind to cis elements of the DNA-B molecules of another virus.

Identification of the Begomoviruses Squash Leaf Curl Virus and Watermelon Chlorotic Stunt Virus in Various Plant Samples in North America

“…During mixed infection, begomoviruses can also undergo pseudo-recombination (or reassortment), i.e., DNA-A and DNA-B components from two different viruses form a new association where the DNA-B is successfully replicated by the DNA-A encoded Rep protein. Both WCSV and SLCV have been, respectively, been found to pseudo-recombine (also referred to as reassortment) with the begomoviruses tomato leaf curl Palampur virus and cucurbit leaf curl virus [ 6 , 51 ]. However, to our knowledge pseudo-recombination between WCSV and SLCV have never been found in nature and have never been experimentally tested.…”

“…Similarly, viable pseudo-recombination has also been detected for the DNA-A and DNA-B of two tomato-infecting begomoviruses with different “iteron” sequences [ 54 ]. In previous reports of successful pseudo-recombination between WCSV and tomato leaf curl Palampur virus (ToLCPMV; [ 51 ]) and between SLCV and cucurbit leaf crumple virus (CuLCV; [ 6 ] the viruses shared similar iterons. It is possible that the iteron sequences are not the only factor contributing to the successful trans-replication of the WCSV DNA-B.…”

“…Although the exact molecular mechanism for this is unclear, since these molecules do not share a similar common region or iteron sequences, this demonstrates that encounters between those two viruses in mixed infection can lead to pseudo-recombination in nature. Previous reports of pseudo-recombination for WCSV with tomato leaf curl Palampur virus [ 51 ] and SLCV with cucurbit leaf crumple virus [ 6 ] exist. However, in both cases, the viruses shared similar iterons.…”

Turnip leaf curl disease associated with two begomoviruses in south-eastern Iran

“…Central and southern Iran have subtropical climatic conditions, which is favorable for whitefly activities and therefore higher incidence of begomoviruses (Esmaeili et al 2015;Fazeli et al 2009;Kheyr-Pour et al 2000). Tomato and watermelon (main hosts of TYLCV and WmCSV, respectively) are extensively grown in Kerman, which is where we identified TYLCV and WmCSV in turnips.…”

“…Following this we screened these samples for begomoviruses using the degenerate primer pair PCRv181 (Rojas et al 1993) and Bc (Deng et al 1994) and all were found to be PCR positive, yielding 550 bp amplicons. Furthermore, given that the begomovirus Watermelon chlorotic stunt virus (WmCSV) is also a major problem in Iran (Esmaeili et al 2015;Kheyr-Pour et al 2000), we tested these samples using the specific primer pair WmCSV-1440A-F (5′-ATC GAT TGT CCC AAC AAG GAC-3′) and WmCSV-2016A-R (5′-TTG CAA TCC GGG CCC ATC TTC-3′).…”