Growth and yield response of a local pepper (Capsicum annuum L.) accession to begomoviral caused disease in the medium elevation land

The experiment aimed to evaluate resistance of a local pepper accession to begomovirus caused disease which is annually observed in pepper cultivation in Aceh, Indonesia. The evaluation was conducted by assessing the growth and yield response of the pepper plants in the median elevation. The field experimental was conducted in Agricultural Staff Training Center (BLPP) Saree and Horticultural Laboratory of Syiah Kuala University from December 2018 to August 2019. Purpose sampling method was established to for plant selection devided into two clusters. The first cluster of 930 plants was evaluated for typical symptom of begomovirus caused disease from 15 to 135 days post transplanting (dpt). Second clusters plants were selected and divided into two group of early-symptomatic and late-symptomatic plants consisted of 12 plants, respectively for polymerase chain reaction (PCR) based begomovirus diagnosis and yield survey. Typical begomovirus symptom started to be observed at 30 dpt in small number of plants (3%) and reach the highest rate (100%) at 105 dpt. The difference productivity of early-symptomatic plants was 0,26 tons ha−1 higher than late-symptomatic plants. Begomovirus species which prevalently infect the plants both early and late symptomatic plants was pepper yellow leaf curl Indonesia virus (PepYLCIV).

Identification of Begomoviruses from Three Cryptic Species of Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) in Nepal

The Bemisia tabaci species complex consists of at least 44 cryptic species, which are potential vectors of approximately 320 begomovirus species, most of which are significant plant viruses. However, the relationship of begomovirus transmission through vectors at the cryptic species level is uncertain. In our previous study, three cryptic species (Asia I, Asia II 1, and Asia II 5) of B. tabaci were identified from 76 B. tabaci samples collected across 23 districts in Nepal. Using the same individuals we identified seven different begomovirus species (Squash leaf curl China virus [SLCCNV], Tomato leaf curl New Delhi virus [ToLCNDV], Okra enation leaf curl virus [OELCuV], Synedrella leaf curl virus [SyLCV], Tomato leaf curl Kerala virus [ToLCKeV], Ageratum enation virus [AEV], and Tomato leaf curl Karnataka virus [ToLCKV]) by PCR using universal begomovirus primers. The begomoviruses were detected in 55.26% of whitefly samples, and SLCCNV was the most prevalent species (27.63%). Among the three cryptic species of B. tabaci, the virus detection rate was highest in Asia I (60%), followed by Asia II 1 (58.82%) and Asia II 5 (53.06%). Most viruses were detected in all three species, but AEV and ToLCKV were found only in Asia I and Asia II 1, respectively. Geographic analysis showed that SLCCNV was distributed in the whole country, which is similar to the distribution of the Asia II 5 species, but OELCuV and SyLCV were detected only in the middle region of Nepal. Our results provide important information on the begomovirus profile in Nepal which can be beneficial for plant virus risk assessment and develop the management strategies to reduce the damage of whitefly transmitted viruses.

The begomovirus species Melon chlorotic leaf curl virus is composed of two highly divergent strains that differ in their genetic and biological properties

Since the early 1990s, squash production in Costa Rica has been affected by a whitefly-transmitted disease characterized by stunting and yellow mottling of leaves. The squash yellow mottle disease (SYMoD) was shown to be associated with a bipartite begomovirus, originally named squash yellow mild mottle virus (SYMMoV). It was subsequently established that SYMMoV is a strain of melon chlorotic leaf curl virus (MCLCuV), a bipartite begomovirus that causes a chlorotic leaf curl disease of melons in Guatemala. In the present study, the complete sequences of the DNA-A and DNA-B components of a new isolate of the strain MCLCuV-Costa Rica (MCLCuV-CR) were determined. Comparisons of full-length DNA-A sequences revealed 97% identity with a previously characterized isolate of MCLCuV-CR, and identities of 90 to 91% with those of isolates of the strain MCLCuV-Guatemala (MCLCuV-GT), which is below or at the current begomovirus species demarcation threshold of 91%. A more extensive analysis of the MCLCuV-CR and -GT sequences revealed substantial divergence in both components and different histories of recombination for the DNA-A components. The cloned full-length DNA-A and DNA-B components of this new MCLCuV-CR isolate were infectious and induced SYMoD in a range of squashes and in pumpkin, thereby fulfilling Koch’s postulates for this disease. However, in contrast to MCLCuV-GT, MCLCuV-CR induced mild symptoms in watermelon and no symptoms in melon and cucumber. Taken together, our results indicate that MCLCuV-CR and -GT have substantially diverged, genetically and biologically, and have evolved to cause distinct diseases of different cucurbit crops. Taxonomically, these viruses are at the strain/species boundary, but retain the designation as strains of Melon chlorotic leaf curl virus under current ICTV guidelines.

First report of begomoviruses infecting Cucumis sativus L. in North America and identification of a proposed new begomovirus species

Background Members of the Begomovirus genus are phytopathogens that infect dicotyledonous plants, producing economic losses in tropical and subtropical regions. To date, only seven species of begomoviruses (BGVs) infecting cucumber have been described. Most cucumber infections were reported in South Asia. In the Americas, begomoviral infections affecting cucumber are scarce; just one report of begomovirus has been described in South America. The presence of whitefly and typical symptoms of viral infections observed in a cucumber field in Colima, Mexico, suggested that plants in this field were affected by BGVs. Methods To identify the BGVs infecting cucumber, we performed a high-throughput sequencing and compared the assembled contigs against the GenBank nucleic acid sequence database. To confirm the presence of viruses in cucumber samples, we performed a PCR detection using specific oligonucleotides. We cloned and sequenced by Sanger method the complete genome of a potential new begomovirus. Begomovirus species demarcation was performed according to the International Committee on Taxonomy of Viruses. The evolutionary relationship of the new virus was inferred using phylogenetic and recombination analyses. Results We identified five species of begomovirus infecting plants in a field. None of these have been previously reported infecting cucumber. One of the five species of viruses here reported is a new begomovirus species. Cucumber chlorotic leaf virus, the new species, is a bipartite begomovirus that has distinctive features of viruses belonging to the squash leaf curl virus clade. Conclusions The findings here described represent the first report of begomoviral infection affecting cucumber plants in North America. Previous to this report, only seven begomovirus species have been reported in the world, here we found five species infecting cucumber plants in a small sample suggesting that cucumber is vulnerable to BGVs. One of these viruses is a new species of begomovirus which is the first begomovirus originally isolated from the cucumber. The findings of this report could help to develop strategies to fight the begomoviral infections that affect cucumber crops.

First report of naturally occurring recombinant non-coding DNA satellite associated with Tomato yellow leaf curl Kanchanaburi virus on eggplant in Indonesia

Kandito A, Hartono S, Sulandari S, Somowiyarjo S, Widyasari YA. 2019. First report of naturally occurring recombinant non-coding DNA satellite associated with Tomato yellow leaf curl Kanchanaburi virus on eggplant in Indonesia. Biodiversitas 20: 129-136. Begomovirus is a viral genus which is a major impediment in the cultivation of plants, especially Solanaceae. Tomato yellow leaf curl Kanchanaburi virus (TYLCKaV) is a member of the Begomovirus genus that is widely reported to infect eggplant and results in severe symptoms of chlorosis. In addition to the type of virus that infects, the severity of symptoms can also be caused by the presence of betasatellite associated with several begomovirus species. The presence of betasatellite that is related to several begomovirus species can lead to more severe symptoms. The aim of this study was to identify satellites associated with begomovirus in Indonesia. Eggplant samples from Bantul, Special Region of Yogyakarta show with mosaic and severe chlorotic symptoms due to Begomovirus infection. Total DNA samples were subject to PCR amplification using universal primer for begomovirus PALIV1978/PAR1C715 and specific primer for betasatellite β01/β02. The PCR amplification produced a DNA band measuring ± 1600bp, identical size of begomovirus. The amplification of the betasatellite specific primer produced a DNA band featuring ± 1300bp, identical size of betasatellites that were associated with begomovirus in the sample. The results of DNA sequencing, suggested that begomovirus in this study had a close relationship with TYLCKaV from Thailand and Indonesia. Characterization of the satellite-based on nucleotide sequence revealed the presence of stem-loop structures, satellite conservative regions, and adenine-rich regions that resembled structures present in the betasatellite, which were associated with Tomato leaf curl virus and Ageratum yellow vein virus, with no ORF found. These results indicated that the TYLCKaV could be associated with a non-coding satellite. This result is the first report regarding the TYLCKaV association with a non-coding satellite in Indonesia.