Dataset Information

Strategies for the Construction of Cassava Brown Streak Disease Viral Infectious Clones.

ABSTRACT: Cassava brown streak disease (CBSD) has major impacts on yield and quality of the tuberous roots of cassava in Eastern and Central Arica. At least two Potyviridae species cause the disease: Cassava brown streak virus (CBSV) and Ugandan cassava brown streak virus (UCBSV). Cloned viral genome sequences known as infectious clones (ICs) have been important in the study of other viruses, both as a means of standardising infectious material and characterising viral gene function. IC construction is often technically challenging for Potyviridae due to sequence instability in E. coli. Here, we evaluate three methods for the construction of infectious clones for CBSD. Whilst a simple IC for in vitro transcription was made for UCBSV isolate 'Kikombe', such an approach failed to deliver full-length clones for CBSV isolates 'Nampula' or 'Tanza', necessitating more complex approaches for their construction. The ICs successfully generated symptomatic infection in the model host N. benthamiana and in the natural host cassava. This shows that whilst generating ICs for CBSV is still a technical challenge, a structured approach, evaluating both in vitro and in planta transcription systems should successfully deliver ICs, allowing further study into the symptomology and virulence factors in this important disease complex.

SUBMITTER: Duff-Farrier CRA

PROVIDER: S-EPMC6513833 | biostudies-literature | 2019 Feb

REPOSITORIES: biostudies-literature

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Strategies for the Construction of Cassava Brown Streak Disease Viral Infectious Clones.

Duff-Farrier C R A CRA Mbanzibwa D R DR Nanyiti S S Bunawan H H Pablo-Rodriguez J L JL Tomlinson K R KR James A M AM Alicai T T Seal S E SE Bailey A M AM Foster G D GD

Molecular biotechnology 20190201 2

Cassava brown streak disease (CBSD) has major impacts on yield and quality of the tuberous roots of cassava in Eastern and Central Arica. At least two Potyviridae species cause the disease: Cassava brown streak virus (CBSV) and Ugandan cassava brown streak virus (UCBSV). Cloned viral genome sequences known as infectious clones (ICs) have been important in the study of other viruses, both as a means of standardising infectious material and characterising viral gene function. IC construction is of ...[more]

PMID: 30484144

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Project description:Cassava mosaic geminiviruses (CMGs) and cassava brown streak viruses (CBSVs) cause the highest yield losses in cassava production in Africa. In particular, cassava brown streak disease (CBSD) is and continues to be a significant constraint to optimal cassava production in Eastern and Southern Africa. While CBSD has not been reported in West Africa, its recent rapid spread and damage to cassava productivity in Eastern, and Southern Africa is alarming. The aim of this study was to evaluate Nigerian cassava genotypes in order to determine their responses to CBSD, in the event that it invades Nigeria, the world's largest cassava producer. The study gathered information on whether useful CBSD resistance alleles are present in the elite Nigerian cassava accessions. A total of 1,980 full-sib cassava seedlings from 106 families were assessed in the field at the seedling stage for a year. A subset of 569 clones were selected and assessed for another year at the clonal stage in Namulonge, central Uganda, a known hotspot for CBSD screening. Results indicated that foliar and root incidences and severities varied significantly (p ≤ 0.01, p ≤ 0.001) except for CBSD foliar incidence at 6 months (CBSD6i ). Highest and lowest plot-based heritability estimates for CBSD were registered for CBSD root severity (CBSD rs ) (0.71) and CBSD6i (0.5). Positive and highly significant correlations were noted between CBSD root incidence (CBSD ri ) and CBSD rs (r = 0.90***). Significant positive correlations were also noted between CBSD foliar severity at 3 months (CBSD3s ) and CBSD foliar incidence at 6 months (CBSD6i ) (r = 0.77***), CBSD3s and CBSD rs (r = 0.35***). Fresh root weight (Fresh RW ) negatively correlated with CBSD ri and CBSD rs , respectively (r = -0.21*** and r = -0.22***). Similarly, CBSD3s correlated negatively with cassava mosaic disease severity at 3 (CMD3s ) and 6 months (CMD6s ), respectively (r = -0.25*** and r = -0.21***). Fifteen clones were selected using a non-weighted summation selection index for further screening. In conclusion, results revealed that the elite Nigerian accessions exhibited significant susceptibility to CBSD within 2 years of evaluation period. It is expected that this information will aid future breeding decisions for the improvement of CBSD resistance among the Nigerian cassava varieties.

Project description:Cassava, a vital global food source, faces a threat from Cassava Brown Streak Disease (CBSD). CBSD results from two viruses: Cassava brown streak virus (CBSV) and Ugandan cassava brown streak virus (UCBSV). These viruses frequently pose challenges to the traditional symptom-based 1-5 phenotyping method due to its limitations in terms of accuracy and objectivity. Quantitative polymerase chain reaction (qPCR) offers precise virus quantification, although high costs hinder its widespread adoption. In this research, we utilized qPCR to measure the viral titer/load of CBSV and UCBSV. The objectives were to evaluate titer variability within the Cycle 2 (C2) population in two different environments, establish connections between viral titers and CBSD severity scores from the 1-5 scoring method, perform Genome-Wide Association Studies (GWAS) to identify genomic regions associated with CBSV and UCBSV titers, and investigate the functional annotated genes. The results demonstrated a significantly higher prevalence of CBSV (50.2%) in clones compared to UCBSV (12.9%) with mixed infections in some cases. Genotypic effects, particularly concerning UCBSV, were significant, with genotype-by-environment effects primarily influencing CBSV titer. GWAS Studies identified genomic regions associated with CBSV and UCBSV titers. Twenty-one SNP markers on chromosomes 10, 13, 17, and 18 exhibited significant associations with CBSV titer, collectively explaining 43.14% of the phenotypic variation. Additionally, 25 SNP markers on chromosomes 1, 2, 4, 5, 8, 11, 12, 13, 16, and 18 were associated with UCBSV titer, and explained 70.71% of the phenotypic variation. No shared genomic regions were identified between CBSV and UCBSV viral titers. Gene ontology analysis also revealed diverse gene functions, especially in transport and catalytic activities. These findings enhance our understanding of virus prevalence, genetics, and molecular functions in cassava plants, offering valuable insights for targeted breeding strategies.

Dataset Information

Strategies for the Construction of Cassava Brown Streak Disease Viral Infectious Clones.

Publications

Strategies for the Construction of Cassava Brown Streak Disease Viral Infectious Clones.

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