Unusual filamentous virus-like particles in symptomless blackberry associated with severe leaf curling in the virus indicator Rubus macraei, and anomalous data using a degenerate badnavirus primer in PCR of Rubus species

Electron microscopy of ultrathin sections of leaves of symptomless Himalaya Giant blackberry and of the virus indicator species, Rubus macraei, showing severe leaf curl symptoms following graft inoculation with scions from this blackberry, detected highly flexuous virus‐like particles with an unusual ‘beaded’ structure. Such particles were restricted to a few vascular cells and were distinct from P‐protein common in some such cells. This virus, provisionally named Hawaiian rubus leaf curl virus (HRLCV), symptomlessly infected a wide range of Rubus species and cultivars. Badnavirus‐like bacilliform particles were observed in some cells of a single R. macraei plant showing leaf curl symptoms following graft inoculation with the causal agent of this disease symptom from Himalaya Giant blackberry after passage through red raspberry, but not in any other material. PCR with primer sets for the badnaviruses Rubus yellow net virus and Gooseberry veinbanding associated virus, showed that no Rubus sources studied contained these viruses. However, using a sequence‐specific primer set designed from the sequence of the product generated with a badnavirus degenerate primer set, a specific product was amplified from healthy plants of all of 16 raspberry cultivars and two Rubus species, but not from 16 blackberry cultivars (including cv. Himalaya Giant). All of these sources were free from viruses known to occur in Rubus. Sequence analysis of this product showed no homology with any known badnavirus, or with any other published sequences. It seems most likely therefore that a region of the raspberry genome has been amplified using the degenerate badnavirus primer set and that it is absent from the blackberry genome.     

Synergistic interactions of begomoviruses with Sweet potato chlorotic stunt virus (genus Crinivirus) in sweet potato (Ipomoea batatas L.)

Three hundred and ninety‐four sweet potato accessions from Latin America and East Africa were screened by polymerase chain reaction (PCR) for the presence of begomoviruses, and 46 were found to be positive. All were symptomless in sweet potato and generated leaf curling and/or chlorosis in Ipomoea setosa. The five most divergent isolates, based on complete genome sequences, were used to study interactions with Sweet potato chlorotic stunt virus (SPCSV), known to cause synergistic diseases with other viruses. Co‐infections led to increased titres of begomoviruses and decreased titres of SPCSV in all cases, although the extent of the changes varied notably between begomovirus isolates. Symptoms of leaf curling only developed temporarily in combination with isolate StV1 and coincided with the presence of the highest begomovirus concentrations in the plant. Small interfering RNA (siRNA) sequence analysis revealed that co‐infection of SPCSV with isolate StV1 led to relatively increased siRNA targeting of the central part of the SPCSV genome and a reduction in targeting of the genomic ends, but no changes to the targeting of StV1 relative to single infection of either virus. These changes were not observed in the interaction between SPCSV and the RNA virus Sweet potato feathery mottle virus (genus Potyvirus), implying specific effects of begomoviruses on RNA silencing of SPCSV in dually infected plants. Infection in RNase3‐expressing transgenic plants showed that this protein was sufficient to mediate this synergistic interaction with DNA viruses, similar to RNA viruses, but exposed distinct effects on RNA silencing when RNase3 was expressed from its native virus, or constitutively from a transgene, despite a similar pathogenic outcome.     

Variation in Virus Symptom Development and Root Architecture Attributes at the Onset of Storage Root Initiation in ‘Beauregard’ Sweetpotato Plants Grown with or without Nitrogen

It has been shown that virus infections, often symptomless, significantly limit sweetpotato productivity, especially in regions characterized by low input agricultural systems. In sweetpotatoes, the successful emergence and development of lateral roots (LRs), the main determinant of root architecture, determines the competency of adventitious roots to undergo storage root initiation. This study aimed to investigate the effect of some plant viruses on root architecture attributes during the onset of storage root initiation in ‘Beauregard’ sweetpotatoes that were grown with or without the presence of nitrogen. In two replicate experiments, virus-tested plants consistently failed to show visible symptoms at 20 days regardless of nitrogen treatment. In both experiments, the severity of symptom development among infected plants ranged from 25 to 118% when compared to the controls (virus tested plants grown in the presence of nitrogen). The presence of a complex of viruses (Sweet potato feathery mottle virus, Sweet potato virus G, Sweet potato virus C, and Sweet potato virus 2) was associated with 51% reduction in adventitious root number among plants grown without nitrogen. The effect of virus treatments on first order LR development depended on the presence or absence of nitrogen. In the presence of nitrogen, only plants infected with Sweet potato chlorotic stunt virus showed reductions in first order LR length, number, and density, which were decreased by 33%, 12%, and 11%, respectively, when compared to the controls. In the absence of nitrogen, virus tested and infected plants manifested significant reductions for all first order LR attributes. These results provide evidence that virus infection directly influences sweetpotato yield potential by reducing both the number of adventitious roots and LR development. These findings provide a framework for understanding how virus infection reduces sweetpotato yield and could lead to the development of novel strategies to mitigate virus effects on sweetpotato productivity.     

Phytoplasma from little leaf disease affected sweetpotato in Western Australia: detection and phylogeny

Symptoms of leaf and stem chlorosis and plant stunting were common in sweetpotato plants (Ipomoea batatas) in farmers’ fields in two widely separated locations, Kununurra and Broome, in the tropical Kimberley region in the state of Western Australia in 2003 and 2004. In the glasshouse, progeny plants developed similar symptoms characteristic of phytoplasma infection, consisting of chlorosis and a stunted, bushy appearance as a result of proliferation of axillary shoots. The same symptoms were reproduced in the African sweetpotato cv. Tanzania grafted with scions from the plant Aus1 with symptoms and in which no viruses were detected. PCR amplification with phytoplasma‐specific primers and sequencing of the 16S‐23S rRNA gene region from two plants with symptoms, Aus1 (Broome) and Aus142A (Kununurra), revealed highly identical sequences. Phylogenetic analysis of the 16S rRNA gene sequences obtained from previously described sweetpotato phytoplasma and inclusion of other selected phytoplasma for comparison indicated that Aus1 and Aus142A belonged to the Candidatus Phytoplasma aurantifolia species (16SrII). The 16S genes of Aus1 and Aus142A were almost identical to those of sweet potato little leaf (SPLL‐V4) phytoplasma from Australia (99.3%–99.4%) but different from those of the sweetpotato phytoplasma from Taiwan (95.5%–95.6%) and Uganda (SPLL‐UG, 90.0%–90.1%). Phylogenetically, Aus1, Aus142A and a phytoplasma previously described from sweetpotato in the Northern Territory of Australia formed a group distinctly different from other isolates within Ca. Phytoplasma aurantifolia species. These findings indicate that novel isolates of the 16SrII‐type phytoplasma pose a potential threat to sustainable sweetpotato production in northern Australia.     

Sweepoviruses cause disease in sweet potato and related Ipomoea spp.: fulfilling Koch's postulates for a divergent group in the genus begomovirus

Sweet potato (Ipomoea batatas) and related Ipomoea species are frequently infected by monopartite begomoviruses (genus Begomovirus, family Geminiviridae), known as sweepoviruses. Unlike other geminiviruses, the genomes of sweepoviruses have been recalcitrant to rendering infectious clones to date. Thus, Koch's postulates have not been fullfilled for any of the viruses in this group. Three novel species of sweepoviruses have recently been described in Spain: Sweet potato leaf curl Lanzarote virus (SPLCLaV), Sweet potato leaf curl Spain virus (SPLCSV) and Sweet potato leaf curl Canary virus (SPLCCaV). Here we describe the generation of the first infectious clone of an isolate (ES:MAL:BG30:06) of SPLCLaV. The clone consisted of a complete tandem dimeric viral genome in a binary vector. Successful infection by agroinoculation of several species of Ipomoea (including sweet potato) and Nicotiana benthamiana was confirmed by PCR, dot blot and Southern blot hybridization. Symptoms observed in infected plants consisted of leaf curl, yellowing, growth reduction and vein yellowing. Two varieties of sweet potato, 'Beauregard' and 'Promesa', were infected by agroinoculation, and symptoms of leaf curl and interveinal loss of purple colouration were observed, respectively. The virus present in agroinfected plants was readily transmitted by the whitefly Bemisia tabaci to I. setosa plants. The progeny virus population present in agroinfected I. setosa and sweet potato plants was isolated and identity to the original isolate was confirmed by sequencing. Therefore, Koch's postulates were fulfilled for the first time for a sweepovirus.     

Identification and distribution of viruses infecting sweet potato in Kenya

Four hundred and forty-eight symptomatic and 638 asymptomatic samples were collected from sweet potato fields throughout Kenya and analysed serologically using antibodies to Sweet potato feathery mottle virus (SPFMV), Sweet potato chlorotic stunt virus (SPCSV), Sweet potato mild mottle virus (SPMMV), Cucumber mosaic virus (CMV), Sweet potato chlorotic fleck virus (SPCFV), Sweet potato latent virus (SwPLV), Sweet potato caulimo-like virus (SPCaLV), Sweet potato mild speckling virus (SPMSV) and C-6 virus in enzyme-linked immunosorbent assays (ELISA). Only SPFMV, SPMMV, SPCSV, and SPCFV were detected. Ninety-two percent and 25% of the symptomatic and asymptomatic plants respectively tested positive for at least one of these viruses. Virus-infected plants were collected from 89% of the fields. SPFMV was the most common and the most widespread, detected in 74% of the symptomatic plants and 86% of fields surveyed. SPCSV was also very common, being detected in 38% of the symptomatic plants and in 50% of the fields surveyed. SPMMV and SPCFV were detected in only 11% and 3% of the symptomatic plant samples respectively. Eight different combinations of these four viruses were found in individual plants. The combination SPFMV and SPCSV was the most common, observed in 22% of symptomatic plants. Virus combinations were rare in the asymptomatic plants tested. Incidence of virus infection was highest (18%) in Kisii district of Nyanza province and lowest (1%) in Kilifi and Malindi districts of Coast province.     

Ipomoea crinkle leaf curl caused by a whitefly-transmitted gemini-like virus

A whitefly-transmitted infectious agent, associated with geminate particles, induced distinct symptoms on several Ipomoea species, but not on I. batatas cv. Georgia Jet. The virus was transmitted by Bemisia argentifolii in a persistent manner and by grafting, but not mechanically. No transmission to species outside Ipomoea was obtained. Extracts from infected Ipomoea plants hybridised with a bean yellow mosaic virus riboprobe and a tomato yellow leaf curl virus riboprobe, although not so strongly as hybridisation of these riboprobes with extracts from plants infected with the homologous viruses. Based on host range, we consider this virus to be distinct from sweet potato leaf curl virus reported from the Far East, and propose it be named “Ipomoea crinkle leaf curl virus” (ICLCV).     

Effects of Sweet Potato Feathery Mottle Virus and Sweet Potato Chlorotic Stunt Virus on the Yield of SweetPotato in Uganda

Sweet potato feathery mottle virus (SPFMV) and Sweet potato chlorotic stunt virus (SPCSV) are the most common viruses infecting sweetpotato in Uganda. Field plots planted with graft inoculated plants of virus‐free cultivars Beauregard, Dimbuka, Ejumula, Kabode and NASPOT 1 were used to assess the effect of SPFMV and SPCSV on yield and quality of sweetpotatoes in two agro‐ecologies. SPFMV spreads rapidly to control plots at Makerere University Agricultural Research Institute Kabanyolo (MUARIK), and these plots had similar yields to those singly infected with SPFMV but at the National Semi Arid Resource Research Institute (NaSARRI) where SPFMV spreads slowly, plots infected with SPFMV yielded 40% less than the control. Recovery from SPFMV appeared to be more frequent at NaSARRI than at MUARIK. Infection by SPCSV alone resulted in yield losses of 14–52%, while mixed infections of SPFMV+SPCSV resulted in yield losses in both locations of 60–95% depending on the cultivar. SPCSV and mixed infections of SPFMV+SPCSV also reduced the number of roots formed as well as the diameter of the roots, resulting in a greater length to diameter ratio compared to the healthy control. This study, therefore, confirms that both SPFMV and SPCSV, both singly and when mixed, can reduce yield, the extent depending on the cultivar. To mitigate the effect of these viruses, farmers should use clean planting materials of resistant varieties.     

Agroinfection of sweet potato by vacuum infiltration of an infectious sweepovirus

Sweepovirus is an important monopartite begomovirus that infects plants of the genus Ipomoea worldwide. Development of artificial infection methods for sweepovirus using agroinoculation is a highly efficient means of studying infectivity in sweet potato. Unlike other begomoviruses, it has proven difficult to infect sweet potato plants with sweepoviruses using infectious clones. A novel sweepovirus, called Sweet potato leaf curl virus-Jiangsu (SPLCV-JS), was recently identified in China. In addition, the infectivity of the SPLCV-JS clone has been demonstrated in Nicotiana benthamiana. Here we describe the agroinfection of the sweet potato cultivar Xushu 22 with the SPLCV-JS infectious clone using vacuum infiltration. Yellowing symptoms were observed in newly emerged leaves. Molecular analysis confirmed successful inoculation by the detection of viral DNA. A synergistic effect of SPLCV-JS and the heterologous betasatellite DNA-β of Tomato yellow leaf curl China virus isolate Y10 (TYLCCNV-Y10) on enhanced symptom severity and viral DNA accumulation was confirmed. The development of a routine agroinoculation system in sweet potato with SPLCV-JS using vacuum infiltration should facilitate the molecular study of sweepovirus in this host and permit the evaluation of virus resistance of sweet potato plants in breeding programs.     

Different effects of exogenous jasmonic acid on preference and performance of viruliferous Bemisia tabaci B and Q

The sweetpotato whitefly, Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae), B and Q biotypes have caused severe losses to crops and vegetables through virus transmission. Our previous studies showed that Q is more efficient than B in acquisition and transmission of tomato yellow leaf curl virus (TYLCV) and viruliferous Q is better equipped than B in counterattacking jasmonic acid (JA)‐related plant defense. To understand how plant‐mediated defensive responses involving JA affect insect vectors within a tritrophic framework of plants, insects, and viruses, we examined the effects of exogenous JA on preference and performance of non‐viruliferous and viruliferous B and Q on tomato plants (Solanum lycopersicum L., Solanaceae). Our results demonstrated a significantly lower fecundity, shorter longevity, shorter developmental time, and lower survival rate of whiteflies on JA‐treated than on control plants. In addition, viruliferous Q performed significantly better than B in fecundity, longevity, developmental time, and survival rate. When given a choice between JA‐treated and control tomato plants, viruliferous Q was not repelled to JA‐treated plants when the JA concentration was 0.01 and 0.1 mm , whereas others all preferred the untreated control plants. Exogenous JA increased the concentration and the composition of plant volatiles, such as α‐terpinene and β‐ocimene, which deterred whiteflies in a Y‐tube bioassay. It is worth noting that Q has a mutualistic relationship with TYLCV to counteract the host defenses. A better understanding of tritrophic interactions between plants, insects, and viruses will facilitate the development of sustainable management of this invasive global pest.     

Tomato yellow leaf curl viruses: ménage à trois between the virus complex,the plant and the whitefly vector

Tomato yellow leaf curl disease (TYLCD) is one of the most devastating viral diseases affecting tomato crops in tropical, subtropical and temperate regions of the world. Here, we focus on the interactions through recombination between the different begomovirus species causing TYLCD, provide an overview of the interactions with the cellular genes involved in viral replication, and highlight recent progress on the relationships between these viruses and their vector, the whitefly Bemisia tabaci. Taxonomy: The tomato yellow leaf curl virus‐like viruses (TYLCVs) are a complex of begomoviruses (family Geminiviridae, genus Begomovirus) including 10 accepted species: Tomato yellow leaf curl Axarquia virus (TYLCAxV), Tomato yellow leaf curl China virus (TYLCCNV), Tomato yellow leaf curl Guangdong virus (TYLCGuV), Tomato yellow leaf curl Indonesia virus (TYLCIDV), Tomato yellow leaf curl Kanchanaburi virus (TYLVKaV), Tomato yellow leaf curl Malaga virus (TYLCMalV), Tomato yellow leaf curl Mali virus (TYLCMLV), Tomato yellow leaf curl Sardinia virus (TYLCSV), Tomato yellow leaf curl Thailand virus (TYLCTHV), Tomato yellow leaf curl Vietnam virus (TYLCVNV) and Tomato yellow leaf curl virus(TYLCV). We follow the species demarcation criteria of the International Committee on Taxonomy of Viruses (ICTV), the most important of which is an 89% nucleotide identity threshold between full‐length DNA‐A component nucleotide sequences for begomovirus species. Strains of a species are defined by a 93% nucleotide identity threshold. Host range: The primary host of TYLCVs is tomato (Solanum lycopersicum), but they can also naturally infect other crops [common bean (Phaseolus vulgaris), sweet pepper (Capsicum annuum), chilli pepper (C. chinense) and tobacco (Nicotiana tabacum)], a number of ornamentals [petunia (Petunia×hybrida) and lisianthus (Eustoma grandiflora)], as well as common weeds (Solanum nigrum and Datura stramonium). TYLCVs also infect the experimental host Nicotiana benthamiana. Disease symptoms: Infected tomato plants are stunted or dwarfed, with leaflets rolled upwards and inwards; young leaves are slightly chlorotic; in recently infected plants, fruits might not be produced or, if produced, are small and unmarketable. In common bean, some TYLCVs produce the bean leaf crumple disease, with thickening, epinasty, crumpling, blade reduction and upward curling of leaves, as well as abnormal shoot proliferation and internode reduction; the very small leaves result in a bushy appearance.     

Occurrence of Six Begomoviruses Infecting Tomato Fields in Venezuela and Genetic Characterization of Potato Yellow Mosaic Virus Isolates

Begomoviruses are one of the major pathogens in tomato crops worldwide. In Venezuela, six begomovirus species have been described infecting tomato: Potato yellow mosaic virus (PYMV), Euphorbia mosaic Venezuela virus (EuMVV), Merremia mosaic virus (MeMV), Tomato chlorotic leaf distortion virus (ToCLDV), Tomato yellow margin leaf curl virus (TYMLCV) and Tomato yellow leaf curl virus (TYLCV). In this study, the occurrence of these viruses was analysed by PCR in 338 tomato plants exhibiting virus‐like symptoms. Sixty‐three per cent of the plants were positive at least to one of the begomoviruses tested. PYMV and TYLCV were the most frequent viruses showing 39.6 and 23.7% occurrence, respectively. Phylogenetic analyses revealed two groups of PYMV isolates from several Caribbean Basin countries. The first group clustered isolates from several countries, including Venezuela, and the second group clustered only Colombian isolates. Due to the high prevalence of PYMV and TYLCV in Venezuela, it is suggested that the surveillance and control strategies currently applied in the country should be focused on these two begomoviruses.     

Aphid-transmitted viruses from lilies in Britain

Three aphid-transmitted viruses, tulip breaking, lily symptomless and cucumber mosaic, were obtained from lilies in Britain. Tulip breaking virus was detected by the leaf mottle produced in Lilium formosanum, cucumber mosaic virus by inoculation of sap to Nicotiana clevelandii and Chenopodium quinoa, and lily symptomless virus by electron microscopy of crude leaf extracts from symptomless L. formosanum. Liiy symptomless virus was transmitted by Myzus persicae, Macrosiphum euphorbiae, Aulacorthum solani and Aphis fabae. M. persicae, which in a small experiment appeared a more efficient vector than A. fabae, transmitted the virus in a non-persistent manner. This conflicts with the original report of transmission in a persistent manner by A. gossypii but no transmission by M. persicae. The possibility that there are two distinct viruses with similar pathological effects is discussed. Tulip breaking and lily symptomless viruses spread to bait plants of L. formosanum within a field planting of lilies in Scotland especially during July to September; lily symptomless virus was the more prevalent. No spread of cucumber mosaic virus was detected.     

Begomoviruses Associated with Leaf Curl Disease of Tomato in Java,Indonesia*

We report that several begomoviruses are associated with tomato leaf curl disease in Java, Indonesia. Tomato plants with leaf curl symptoms were collected from Bandung (west Java), Purwokerto (central Java), Magelang (central Java) and Malang (east Java) of Indonesia, the major tomato‐growing areas of the country. Viruses were detected using the polymerase chain reaction (PCR), with universal primers for the genus Begomovirus. PCR‐amplified fragments were cloned and sequenced. Based on sequence comparisons and phylogenetic analyses, the viruses were divided into three groups. With respect to amino acid (aa) identities of the N‐terminal halves of the coat proteins compared in this study, group I was most closely related to Ageratum yellow vein virus (AYVV) (97%), Ageratum yellow vein China virus‐[Hn2] (AYVCNV‐[Hn2]) (96%) and Ageratum yellow vein virus‐[Taiwan] (AYVV‐[Tai]) (95%), and ageratum‐infecting begomovirus from Java (99%). Group II had high sequence identity with a tentative species of tomato leaf curl Java virus (ToLCJAV) (96% aa) for the CP. Group III was most closely related to a proposed species of Pepper yellow leaf curl Indonesia virus (PepYLCIDV) (90% aa identity) by its partial CP sequence.     

Detection and relationships of cotton leaf curl virus and allied whitefly-transmitted geminiviruses occurring in Pakistan

A stock culture of cotton leaf curl virus from Pakistan (CLCuV-PK), was transmitted by whiteflies (Bemisia tabaci) to seven plant species, including French bean, okra, tobacco and tomato, and caused vein thickening and leaf curl symptoms. It was readily detected in triple antibody sandwich ELISA (TAS-ELIS A) by 11 out of 31 monoclonal antibodies raised against the particles of three other geminiviruses: African cassava mosaic, Indian cassava mosaic and okra leaf curl viruses. Reaction strength was enhanced when the tissue extraction fluid contained sodium sulphite. Minor variations in epitope profile were found among virus isolates from cotton (Gossypium hirsutum) collected from different districts in Pakistan over a 5-year period. These epitope profiles were distinguishable from that of cotton leaf curl virus from G. barbadense in southern India but indistinguishable from the profiles of viruses causing yellow vein disease of okra in India or Pakistan, or leaf curl of okra {Abelmoschus esculentus), Hibiscus tiliaceus, radish or sunflower in Pakistan, suggesting that these plants are putative natural hosts of CLCuV-PK. The viruses in cotton, and in okra with leaf curl or yellow vein symptoms, were also detected by PCR with three pairs of CLCuV-PK-specific primers. Five additional whitefly-transmitted geminiviruses were found among isolates from 11 other naturally-infected species in Pakistan, and were distinguished by their epitope profiles. These viruses were associated, respectively, with tobacco leaf curl, squash yellow blotch, tomato yellow leaf curl, watermelon leaf crinkle and soybean yellow mosaic diseases. The first four of these viruses were detected readily by PCR with geminivirus general primers but only weakly, if at all, with two pairs of CLCuV-PK-specific primers. Pakistani crops are infected with a range of distinguishable but relatively closely related whitefly-transmitted geminiviruses, some of which resemble those found in India.     

Molecular Evidence for the Association of Tomato leaf curl Gujarat virus with a Leaf Curl Disease of Phaseolus vulgaris L.

A leaf curl disease with symptoms typical of begomoviruses was observed in bean (Phaseolus vulgaris) at the Main Research Farm of the Indian Institute of Pulses Research, Kanpur, India. Infected plants had severe distortion of leaves and the plants were unproductive. PCR indicated the involvement of French bean leaf curl virus (JQ866297), a recently described Begomovirus, and Tomato leaf curl Gujarat virus (ToLCGV). The full‐length genome of ToLCGV associated with leaf curl disease of bean was 2757 nucleotides long and had maximum identity (97–98%) with seven isolates of ToLCGV (AY234383, AF449999, EU573714, GQ994098, AY190290, FR819708, AF413671) and is designated as Tomato leaf curl Gujarat virus‐(IN:Knp:Bean:2013) (KF440686). To the best of our knowledge, this is the first record of ToLCGV infecting a leguminous host, P. vulgaris.     

Development of plants resistant to tomato geminiviruses using artificial trans‐acting small interfering RNA

RNA interference (RNAi), a conserved RNA‐mediated gene regulatory mechanism in eukaryotes, plays an important role in plant growth and development, and as an antiviral defence system in plants. As a counter‐strategy, plant viruses encode RNAi suppressors to suppress the RNAi pathways and consequently down‐regulate plant defence. In geminiviruses, the proteins AC2, AC4 and AV2 are known to act as RNAi suppressors. In this study, we have designed a gene silencing vector using the features of trans‐acting small interfering RNA (tasiRNA), which is simple and can be used to target multiple genes at a time employing a single‐step cloning procedure. This vector was used to target two RNAi suppressor proteins (AC2 and AC4) of the geminivirus, Tomato leaf curl New Delhi virus (ToLCNDV). The vector containing fragments of ToLCNDV AC2 and AC4 genes, on agro‐infiltration, produced copious quantities of AC2 and AC4 specific siRNA in both tobacco and tomato plants. On challenge inoculation of the agro‐infiltrated plants with ToLCNDV, most plants showed an absence of symptoms and low accumulation of viral DNA. Transgenic tobacco plants were raised using the AC2 and AC4 tasiRNA‐generating constructs, and T₁ plants, obtained from the primary transgenic plants, were tested for resistance separately against ToLCNDV and Tomato leaf curl Gujarat virus. Most plants showed an absence of symptoms and low accumulation of the corresponding viruses, the resistance being generally proportional to the amounts of siRNA produced against AC2 and AC4 genes. This is the first report of the use of artificial tasiRNA to generate resistance against an important plant virus.