In October 2019, tomato (Solanum lycopersicum L.) plants showing chlorosis and brown necrosis in apical leaflets and rugose surface in fruits were observed in a greenhouse in Vicar, Almería, Spain....

In two successive winters (2009 and 2010), 14 hot pepper (Capsicum annuum) samples showing unusual symptoms were surveyed in permanently irrigated seasonal vegetable gardens along the Blue Nile in central Sudan (specifically in Gezira State). Symptoms included leaf curling, leaf deformation, reduced leaf size, leaf puckering, interveinal yellowing, vein clearing, or yellow patches. Total RNA was extracted from symptomatic leaves and analyzed by reverse transcription (RT)-PCR with degenerate primer pairs that amplify different viral species within the family Luteoviridae (1). Amplification of a 340-bp fragment of the coat protein gene (CP) was obtained in all the collected samples analyzed. The amplified fragments were purified and sequenced (Accession Nos. KC685313 to 26), showing 99, 97, and 95 to 99% nucleotide identities to Pepper yellows virus (PYV, accession no. FN600344 from Turkey), Pepper vein yellows virus (PeVYV, AB594828 from Japan) and Pepper yellow leaf curl virus (PYLCV, HM439608 from Israel), respectively. These three viruses belong to the genus Polerovirus and are considered synonyms of the same virus species PeVYV described with those names in different countries (3). Two samples were also tested by RT-PCR with the general Polerovirus primer pair Pol-G-F and Pol-G-R, which amplified a 1.1-kb product spanning the 3′ half of the RNA-dependent RNA polymerase (RdRp) to the 5′ half of CP and movement protein (2). The amplified fragments (KC692834 and KC692833) showed 97, 96, and 95% nt identity with PYV (FN600344), PeVYV (JX427533), and PYLCV (HM439608), respectively. The presence of the recently described Polerovirus PeVYV is the first report of detection in pepper in Sudan. PeVYV has recently been identified in seven other countries (India, Indonesia, Mali, the Philippines, Spain, Taiwan, and Thailand) and on one new host, Solanum nigrum, which suggests this new Polerovirus species poses a potentially wide geographical distribution and a global threat for pepper crops (3,4). References: (1) A. D. Abraham et al. Afr. J. Biotechnol. 7:414, 2008. (2) D. Knierim et al. Plant Pathol. 59:991, 2010. (3) D. Knierim et al. Arch. Virol. 158:1337, 2013. (4) F. Villanueva et al. Plant Dis. 97:1261, 2013.

Tomato mosaic virus (ToMV), a member of the genus Tobamovirus, infects several ornamental and horticultural crops worldwide. In this study, the nucleotide sequences of the coat protein gene of worldwide ToMV isolates were analyzed to estimate the genetic structure and diversity of this virus and the involved evolutionary forces. The phylogenetic analysis showed three clades with high bootstrap support: Clade I contained three ToMV isolates from Brazil collected from pepper, Clade II comprised one Brazilian ToMV isolate from pepper, and Clade III was composed of ToMV isolates collected from different plant hosts (pepper, tomato, eggplant, lilac, camellia, dogwood, red spruce, etc.) and water (from melting ice, lakes and streams) from different countries: USA, Brazil, Korea, Germany, Spain, Denmark (Greenland), China, Taiwan, Malaysia, Iran, and Kazakhstan. With the exception of Brazil, nucleotide diversity within and between different geographic regions was very low, although statistical analyses suggested some gene flow between most of these regions. Our analyses also suggested a strong negative selection which could have contributed to the genetic stability of ToMV.

Optical and electron microscopy studies were carried out to investigate the cytopathology induced in tomato leaves infected by Tomato torrado virus (ToTV), a new picorna‐like virus associated with the ‘Torrado’ disease. Infected leaves, showing typical Torrado disease symptoms were surveyed in commercial greenhouses in the main tomato production areas of Spain. The effect of the co‐infection of ToTV with other viruses which commonly infect tomato crops was also studied. Ultra‐thin sections of ToTV‐infected tomato leaves did not show a strong cellular alteration. However, crystalline arrays of isometric virus‐like particles (VLPs) of 20–30 nm in the inclusion bodies were observed in phloem parenchyma cells of the infected tissues. Tissues co‐infected by ToTV and either Tomato chlorosis virus (ToCV) or Pepino mosaic virus (PepMV) presented more severe cellular alterations. The most deleterious consequences for tomato cells were found in triple infections of ToTV, PepMV and Tomato spotted wilt virus (TSWV), where characteristic cell wall overgrowth was distinguishable, together with a large amount of necrotic cells.

An isolate of chili pepper mild mottle virus (CPMMV-Sp; GenBank OQ920979) with a 99% identity to CPMMV (GenBank MN164455.1) was found in symptomatic pepper plants in Spain. RACE analysis, performed using a stem-loop primer developed in this study to prime at the end of the introduced poly(A)/(U) tail, revealed the presence of an extra 22 nt at the 5' end, starting with a cytosine, which were essential to generate infectious clones. However, the 5' terminal cytosine was dispensable for initiating the infection. The design of two specific digoxigenin riboprobes targeting the more divergent area of CPMMV-Sp, compared to the closely related bell pepper mottle virus (BPeMV) (identity percentage of 80.6% and 75.8%, respectively), showed that both probes specifically detected CPMMV-Sp when the hybridization was performed at 68ºC and 60ºC, respectively. However, the BPeMV probe, targeting a region with an 89.4% identity percentage to CPMMV-Sp, showed cross-hybridization at 60ºC but not at 68ºC. The comparison of the detection limits between molecular hybridization and RT-PCR techniques revealed that the former was 125 times less sensitive than RT-PCR. The analysis of the vertical transmission of CPMMV-Sp using seeds from naturally or mechanically infected pepper plants revealed a transmission percentage ranging from 0.9% to 8.5%. Finally, the analysis of the resistance of capsicum species carrying different alleles of the L gene (L1, L2, L3, and L4) revealed that varieties with the L1 gene were infected by CPMMV-Sp (20–40% of inoculated plants), while varieties with the L2, L3, and L4 genes were resistant.