Cassava brown streak virus has a rapidly evolving genome: implications for virus speciation, variability, diagnosis and host resistance

Alicai, Titus; Ndunguru, Joseph; Sseruwagi, Peter; Tairo, Fred; Okao-Okuja, Geoffrey; Nanvubya, Resty; Kiiza, Lilliane; Kubatko, Laura; Kehoe, Monica A.; Boykin, Laura M.

doi:10.1038/srep36164

Cited by 76 publications

(79 citation statements)

References 53 publications

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“…The causal viruses of CMD are: African cassava mosaic virus-Kenya (ACMV-K), and East African cassava mosaic virus (EACMV), East African cassava mosaic Zanzibar virus (EACMZV), Uganda variant strain of the EACMV (EACMV-Ug), and East African cassava mosaic Kenya Virus (EACMKV) and for cassava brown streak disease there are two recognized species, Cassava brown streak virus and Uganda cassava brown streak virus with many more being uncovered as more genomes are characterized [14,15]. The challenge now is to match these many viruses of CMD and CBSD with the many species in the Bemisia tabaci species complex.…”

Section: Discussionmentioning

confidence: 99%

“…CBSD, on the other hand, is caused by Cassava brown streak virus (CBSV) and Uganda cassava brown streak virus (UCBSV) [11,14]. Recent studies have revealed there are several species of CBSD [14], and CBSD has an accelerated rate of evolution [15]. The disease is characterized by severe chlorosis and necrosis on infected leaves, giving them a yellowish, mottled appearance.…”

Section: Introductionmentioning

confidence: 99%

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Phylogenetic Relationships among Whiteflies in the Bemisia tabaci (Gennadius) Species Complex from Major Cassava Growing Areas in Kenya

Manani

Ateka

Nyanjom

et al. 2017

Insects

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Whiteflies, Bemisia tabaci (Gennadius) are major insect pests that affect many crops such as cassava, tomato, beans, cotton, cucurbits, potato, sweet potato, and ornamental crops. Bemisia tabaci transmits viral diseases, namely cassava mosaic and cassava brown streak diseases, which are the main constraints to cassava production, causing huge losses to many small-scale farmers. The aim of this work was to determine the phylogenetic relationships among Bemisia tabaci species in major cassava growing areas of Kenya. Surveys were carried out between 2013 and 2015 in major cassava growing areas (Western, Nyanza, Eastern, and Coast regions), for cassava mosaic disease (CMD) and cassava brown streak disease (CBSD). Mitochondrial cytochrome oxidase I (mtCOI-DNA) was used to determine the genetic diversity of B. tabaci. Phylogenetic trees were constructed using Bayesian methods to understand the genetic diversity across the study regions. Phylogenetic analysis revealed two B. tabaci species present in Kenya, sub-Saharan Africa 1 and 2 comprising five distinct clades (A–E) with percent sequence similarity ranging from 97.7 % to 99.5%. Clades B, C, D, and E are predominantly distributed in the Western and Nyanza regions of Kenya whereas clade B is dominantly found along the coast, the eastern region, and parts of Nyanza. Our B. tabaci clade A groups with sub-Saharan Africa 2-(SSA2) recorded a percent sequence similarity of 99.5%. In this study, we also report the identification of SSA2 after a 15 year absence in Kenya. The SSA2 species associated with CMD has been found in the Western region of Kenya bordering Uganda. More information is needed to determine if these species are differentially involved in the epidemiology of the cassava viruses.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Phylogenetic Relationships among Whiteflies in the Bemisia tabaci (Gennadius) Species Complex from Major Cassava Growing Areas in Kenya

Manani

Ateka

Nyanjom

et al. 2017

Insects

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“…Studies on characterization and evolution of cassava brown streak viruses have revealed different genetic sequences between CBSV and UCBSV, and that genetic diversity is wider among CBSV isolates (Monger et al ., ; Mbanzibwa et al ., ). A recent report suggests that there may be as many as four distinct viral species causing CBSD (Ndunguru et al ., ; Alicai et al ., ).…”

Section: Introductionmentioning

confidence: 97%

Cassava brown streak disease in Rwanda, the associated viruses and disease phenotypes

et al. 2017

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Cassava brown streak disease (CBSD) was first observed on cassava (Manihot esculenta) in Rwanda in 2009. In 2014 eight major cassava‐growing districts in the country were surveyed to determine the distribution and variability of symptom phenotypes associated with CBSD, and the genetic diversity of cassava brown streak viruses. Distribution of the CBSD symptom phenotypes and their combinations varied greatly between districts, cultivars and their associated viruses. The symptoms on leaf alone recorded the highest (32.2%) incidence, followed by roots (25.7%), leaf + stem (20.3%), leaf + root (10.4%), leaf + stem + root (5.2%), stem + root (3.7%), and stem (2.5%) symptoms. Analysis by RT‐PCR showed that single infections of Ugandan cassava brown streak virus (UCBSV) were most common (74.2% of total infections) and associated with all the seven phenotypes studied. Single infections of Cassava brown streak virus (CBSV) were predominant (15.3% of total infections) in CBSD‐affected plants showing symptoms on stems alone. Mixed infections (CBSV + UCBSV) comprised 10.5% of total infections and predominated in the combinations of leaf + stem + root phenotypes. Phylogenetic analysis and the estimates of evolutionary divergence, using partial sequences (210 nt) of the coat protein gene, revealed that in Rwanda there is one type of CBSV and an indication of diverse UCBSV. This study is the first to report the occurrence and distribution of both CBSV and UCBSV based on molecular techniques in Rwanda.

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“…The ultimate goal in breeding for cassava resistance to pests is the possibility of developing varieties that have relative resistance to B. tabaci adapted to a wide range of environments (Alicai et al, 2016), forming a basis of an integrated approach to B. tabaci control and ACMD control. The objective of the study focused on assessing genotype × environment interaction (GEI) and Bemisia tabaci effect on tannin, flavonoid, total phenolic concentration and antioxidative capacity.…”

Section: Introductionmentioning

confidence: 99%

Genotype by Environment Interaction Unravels Influence on Secondary Metabolite Quality in Cassava Infested by Bemisia tabaci

Mwila¹,

Nuwamanya²,

Odong³

et al. 2018

JAS

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Cassava resistance to Bemisia tabaci is a result of many plant processes which involve plant biochemical constituents, shown to be affected by genotype and environment. The objective of this study was to assess the effect of genotype × environment interactions on concentrations of tannin, flavonoid, total phenolic content, antioxidative capacity and B. tabaci resistance. Fifteen cassava genotypes were evaluated monthly for tannin, flavonoid, total phenolic content and antioxidative capacity in three locations over two seasons with varying temperatures and rainfall. In addition, data were collected on B. tabaci population density and damage. The data collected was subjected to analysis of variance and additive main effects and multiplicative interactions (AMMI) analyses. Flavonoid, total phenolic content and antioxidative capacity varied significantly (P < 0.001) across seasons with higher concentrations in season one than season two, attributed to different temperature and rainfall readings. Total phenolic content was significantly (P < 0.001) associated to antioxidative capacity (r = 0.83) and temperature (r = 0.91). Leaf damage due to adult whitefly and nymphs was significantly (P < 0.001) negatively correlated (r = -0.67) to antioxidative capacity. Genotypes UG 120257, UG 120291 and UG 120124 were shown to have high antioxidative capacity and more stable performance across environments. Temperature and B. tabaci feeding influenced concentrations of the phenolic content and antioxidative activity, as a result affected cassava resistance.

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Cassava brown streak virus has a rapidly evolving genome: implications for virus speciation, variability, diagnosis and host resistance

Cited by 76 publications

References 53 publications

Phylogenetic Relationships among Whiteflies in the Bemisia tabaci (Gennadius) Species Complex from Major Cassava Growing Areas in Kenya

Phylogenetic Relationships among Whiteflies in the Bemisia tabaci (Gennadius) Species Complex from Major Cassava Growing Areas in Kenya

Cassava brown streak disease in Rwanda, the associated viruses and disease phenotypes

Genotype by Environment Interaction Unravels Influence on Secondary Metabolite Quality in Cassava Infested by Bemisia tabaci

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