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Js redirector bmu8/5/2023 ![]() Genome maps were constructed in SnapGene. This region overlaps with the open-reading frames for AV1 (CP) and AC5. The area of recombination between ACMV and EACMV is marked as Region B. This region overlaps with the AC4 and AC1 (Rep) open-reading frames. The ~400-bp region that distinguishes EACMV-like species is marked as Region A. Viral open-reading frames and genes are marked on both components. Genome map showing the DNA-A and DNA-B components of EACMV. Begomoviruses have high rates of mutation and recombination, leading to intra-host diversity and the emergence of novel species of begomoviruses (Duffy and Holmes, 2008, 2009 Crespo-Bellido et al., 2021 Mishra et al., 2022). CMBs are transmitted by whiteflies in the Bemisia tabaci cryptic species complex in a persistent, non-propagative manner (Mugerwa et al., 2012). The AC5 ORF is hypothesized to have anti-silencing functions (Wu et al., 2022). The DNA-A component encodes for replication (Rep, REn), encapsidation (CP), and anti-host defense functions (TrAP, AV2, and AC4), whereas the DNA-B component encodes for two movement proteins-the nuclear shuttle protein (NSP) and the movement protein (MP) (Hanley-Bowdoin et al., 2013). Both components are required to establish a systemic infection ( Figure 1). Cassava mosaic begomoviruses (CMBs) have bipartite genomes with DNA-A and DNA-B components. Although economic losses caused by CMD have not been calculated on a regional scale since the early 2000s (Legg et al., 2006), recent estimates point to sustained crop losses in both Kenya and other East African countries (Arama et al., 2016 Tembo et al., 2017).Ĭassava mosaic disease (CMD) is caused by a complex of single-stranded DNA viruses in the Begomovirus genus (family: Geminiviridae) (Patil and Fauquet, 2009). These physiological changes impact storage root development and often cause severe reduction in size. CMD is characterized by leaf yellowing, deformation, and stunting. Cassava is a promising crop, but its production is threatened by several viral diseases, including cassava mosaic disease (CMD)-a viral disease that is endemic across Africa and causes major crop losses (Legg et al., 2011 Rey and Vanderschuren, 2017). ![]() Production of cassava is expected to increase to meet the anticipated decrease in the production of maize and rice as temperature increases (MoALFI, 2019 Ray et al., 2019 Harvesters, 2021). Sub-Saharan Africa produces over half of the cassava grown worldwide (Food Agriculture Organization of the United Nations, 2020). Storage roots are harvested for consumption and commercial applications and are important for both food and economic security in Africa. These results suggest that whitefly transmission and vegetative transmission lead to different outcomes for ACMV and EACMV-like viruses.Ĭassava ( Manihot esculenta Crantz) is a temperature-resilient and drought-resistant crop that is important to smallholder farmers. Only ACMV was transmitted by whiteflies from these plants to recipient plants, as indicated by sequencing reads and copy number data. Cassava plants were inoculated with ACMV and another EACMV-like virus, East African cassava mosaic Cameroon virus (EACMCV). This differed from whitefly transmission results. ![]() The results suggest that in these samples, EACMV becomes the dominant virus through vegetative propagation in a greenhouse. After 3 years of regrowth in the greenhouse, only EACMV-like viruses were detected in all samples. Many of the field-collected samples had mixed infections of EACMV and another begomovirus. In the field-collected samples, African cassava mosaic virus (ACMV), East African cassava mosaic virus (EACMV), East African cassava mosaic Kenya virus (EACMKV), and East African cassava mosaic virus-Uganda variant (EACMV-Ug) were detected in samples from the Lake Victoria region, while EACMV and East African mosaic Zanzibar virus (EACMZV) were found in the coastal region. The field-collected and greenhouse samples were sequenced using Illumina short-read sequencing and analyzed on the Galaxy platform. ![]() Cassava plants with CMD symptoms were sampled in Lake Victoria and coastal regions of Kenya before transfer to a greenhouse setting and regular propagation. Understanding the dynamics of different cassava mosaic begomovirus (CMB) species through time is important for contextualizing disease trends. Cassava production is threatened by Cassava mosaic disease (CMD), which is caused by a complex of single-stranded DNA viruses (family: Geminiviridae, genus: Begomovirus) that are transmitted by the sweet potato whitefly ( Bemisia tabaci). Cassava is a root crop important for global food security and the third biggest source of calories on the African continent. ![]()
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