Near-complete genome sequence and biological properties of an allexivirus found in Senna rizzinii in Brazil.

Senna rizzinii is a flowering shrub found mainly in the northeast region of Brazil. Here, we report the coding-complete genome sequence, particle morphology, mode of transmission, and the indicator host responses of an isolate of the putative allexivirus cassia mild mosaic virus (CaMMV) found in S. rizzinii. The virus was transmitted mechanically to Chenopodium amaranticolor, C. quinoa, Gomphrena globosa, which showed local lesions, and S. rizzinii, and S. occidentalis, which were infected systemically. It was also efficiently transmitted to S. rizzinii by grafting. Seed transmission was not observed. The near-complete genome sequence of the virus is 7829 nucleotides in length, containing six open reading frames (ORF), like other allexiviruses.

Biological and molecular characterization of a putative new potexvirus infecting Senna occidentalis.

In this work, we report the complete genome sequence of, production of polyclonal antibodies against, and development of biological assays for a putative new potexvirus, named senna mosaic virus (SenMV), found infecting Senna occidentalis in the state of São Paulo, Brazil. The complete genome sequence of SenMV comprises 6775 nucleotides excluding the poly(A) tail. The genome organization is similar to those of other potexviruses, with five open reading frames coding for RNA-dependent RNA polymerase (RdRp), the triple gene block (TGB 1, 2, and 3) proteins, and coat protein (CP). The virus was transmitted to S. occidentalis by mechanical inoculation and trimming scissors, but not by seeds.

Senna leaf curl virus: a novel begomovirus identified in Senna occidentalis.

Begomoviruses are whitefly-transmitted, single-stranded DNA viruses that infect a variety of cultivated (crop) and non-cultivated (weed) plants. The present study identified a novel begomovirus and satellites (alpha- and betasatellite) in Senna occidentalis (syn. Cassia occidentalis) showing leaf curl symptoms. The begomovirus shared a maximum sequence identity of 88.6 % with french bean leaf curl virus (JQ866297), whereas the alphasatellite and the betasatellite shared identities of 98 % and 90 % with ageratum yellow vein India alphasatellite (LK054802) and papaya leaf curl betasatellite (HM143906), respectively. No other begomovirus or satellites were detected in the suspected plants. We propose to name the virus "senna leaf curl virus" (SenLCuV).

A mosaic disease of Senna hirsuta induced by a potyvirus in Nigeria.

A virus inducing mosaic and severe leaf malformation, isolated from Senna hirsuta in Nigeria, was studied. The virus had a rather narrow host range, infecting a few species in Caesalpinaceae, Chenopodiaceae and Fabaceae families. The virus was widespread in southern Nigeria with prevalence ranging from 74% to 86.4% in some locations. It was transmitted mechanically and in a non-persistent manner by Myzuspersicae, Aphis craccivora and A. spiraecola. There was no evidence of transmission by seeds. Electron microscopy of leaf dip preparations revealed flexuous rod-shaped particles. The viral coat protein had Mr of 32.5 K. The virus reacted positively with a monoclonal antibody (MAb) to peanut stripe virus specific for potyviruses (members of the Potvvirus genus) and with antisera to turnip mosaic virus (TuMV), potato virus Y (PVY), TuMV, potato virus A (PVA), potato virus V (PVV) and bean yellow mosaic virus (BYMV), but it failed to react with antisera to celery mosaic virrus (CeMV), bean common mosaic virus (BCMV), soybean mosaic virus (SMV), and clover yellow mosaic virus (ClYMV) in plate-trapped ELISA (PTA-ELISA). No positive reaction was obtained when the virus was tested against any of the antisera in double-antibody sandwich ELISA (DAS-ELISA). This is the first report of natural infection of Senna species in Nigeria. The virus, tentatively designated as Senna mosaic virus (SeMV), seems to differ from other viruses previously described from Senna species in the literature and indeed other legume potyviruses in Nigeria.