Joseph Ndunguru

Mikocheni Agricultural Research Institute (MARI) · DRD

Cassava is a major crop in Sub-Saharan Africa, where it is grown primarily by smallholder farmers. Cassava production is constrained by Cassava mosaic disease (CMD), which is caused by a complex of cassava mosaic begomoviruses (CMBs). A previous study showed that SEGS-1 (sequences enhancing geminivirus symptoms), which occurs in the cassava genome...

Background: Cassava leaf samples can degrade quickly during storage and transportation from distant areas. Proper sampling and the use of efficient cheap storage methods are critical to obtain sufficient quality of DNA and RNA for plant virus epidemiology and to improve understanding on disease control. This is practical when samples are collected...

Cassava mosaic disease (CMD), which is caused by single-stranded DNA begomoviruses, severely limits cassava production across Africa. A previous study showed that CMD symptom severity and viral DNA accumulation increase in cassava in the presence of a DNA sequence designated as SEGS-2 ( s equence e nhancing g eminivirus s ymptoms). We report here t...

Cassava mosaic disease (CMD), which is caused by single-stranded DNA begomoviruses, severely limits cassava production across Africa. A previous study showed that CMD symptom severity and viral DNA accumulation increase in cassava in the presence of a DNA sequence designated as SEGS-2 ( s equence e nhancing g eminivirus s ymptoms). We report here t...

Cassava is a staple food crop in sub-Saharan Africa; it is a rich source of carbohydrates and proteins which currently supports livelihoods of more than 800 million people worldwide. However, its continued production is at stake due to vector-transmitted diseases such as Cassava mosaic disease and Cassava brown streak disease. Currently, the manage...

Cassava brown streak disease (CBSD) is currently the most devastating cassava disease in eastern, central and southern Africa affecting a staple crop for over 700 million people on the continent. A major outbreak of CBSD in 2004 near Kampala rapidly spread across Uganda. In the following years, similar CBSD outbreaks were noted in countries across...

Begomoviruses are plant viruses that cause major losses to many economically important crops. Although they are poorly understood, begomoviruses infecting wild plants may have an important role as reservoirs in the epidemiology of viral diseases. This study reports the discovery and genomic characterization of three novel bipartite begomoviruses fr...

In this case study we successfully teamed the PDQeX DNA purification technology developed by MicroGEM, New Zealand, with the MinION and MinIT mobile sequencing devices developed by Oxford Nanopore Technologies to produce an effective point-of-need field diagnostic system. The PDQeX extracts DNA using a cocktail of thermophilic proteinases and cell...

In this case study we successfully teamed the PDQeX DNA purification technology developed by MicroGEM, New Zealand, with the MinION and MinIT mobile sequencing devices developed by Oxford Nanopore Technologies to produce an effective point-of-need field diagnostic system. The PDQeX extracts DNA using a cocktail of thermophilic proteinases and cell...

Over the last 20 years the authors have been involved in collaborative research projects in Africa, where we have gained valuable experience and knowledge in effective collaboration in agricultural development and research for impact. We have effectively collaborated with more than 100 number of institutions globally, regionally, and nationally on...

Root necrosis similar to those of the cassava brown streak disease (CBSD) were observed on cassava in western provinces of the Democratic Republic of Congo (DR.Congo) in the early 2000’s. However molecular laboratory diagnosis were not able to detect any causative agent responsible for the attacks, hence, the disease related to these symptoms was n...

A number of stakeholders benefited from the implementation of the CDP – there is now a strong connection with the end-users of the science and technology. Farmers who used to get less than 5 t/ha of cassava before the project intervention are now getting 20–45 t/ha after receiving virus-free improved cassava material from the project. This has sign...

Plant viruses represent a significant threat to food security for many global populations. Cassava Brown Streak Virus (CBSV) causes immense damage to cassava crops in Eastern, Central and Southern Africa. The eradication of CBSV is a difficult challenge, as it has been shown to be fast-evolving and it is transmitted by flying insects that are ubiqu...

Cassava brown streak disease (CBSD) and cassava mosaic disease (CMD) are two viral diseases that cause severe yield losses in cassava of up to 100%, thereby persistently threatening food and income security in sub-Saharan Africa. For effective management of these diseases, there is a critical need to develop and deploy varieties with dual resistanc...

Cassava brown streak disease (CBSD) caused by Cassava brown streak virus (CBSV) and Ugandan cassava brown streak virus (UCBSV) is the main constraint to cassava (Manihot esculenta Crantz) production in Mozambique. Using RT-PCR to amplify partial coat protein nucleotide sequences, we detected for the first time the occurrence of CBSV in two non-cass...

Background: Cassava brown streak disease (CBSD) has a viral aetiology and is caused by viruses belonging to the genus Ipomovirus (family Potyviridae), Cassava brown streak virus (CBSV) and Ugandan cassava brown streak virus (UCBSV). Molecular and serological methods are available for detection, discrimination and quantification of cassava brown st...

Crop losses due to viral diseases and pests are major constraints on food security and income for millions of households in sub-Saharan Africa (SSA). Such losses can be reduced if plant diseases and pests are correctly diagnosed and identified early. Currently, accurate diagnosis for definitive identification of plant viruses and their vectors in S...

The United Nations has listed Zero Hunger as one of the 17 global sustainable development goals to end extreme poverty by 2030. Plant viruses are a major constraint to crop production globally causing an estimated $30 billion in damage leaving millions of people food insecure. In Africa, agriculture employs up to 50% of the workforce, yet only cont...

Cassava varieties resistant to cassava mosaic disease (CMD) and cassava brown streak disease (CBSD) are needed for the food and income security of the rural poor in eastern and southern Africa (ESA). The International Institute of Tropical Agriculture led five national cassava breeding programs (Malawi, Mozambique, Kenya, Tanzania and Uganda) in vi...

Background: Bemisia tabaci species (B. tabaci), or whiteflies, are the world's most devastating insect pests. They cause billions of dollars (US) of damage each year, and are leaving farmers in the developing world food insecure. Currently, all publically available transcriptome data forB. tabaciare generated from pooled samples, which can lead to...

Background: Bemisia tabaci species ( B. tabaci ), or whiteflies, are the world’s most devastating insect pests. They cause billions of dollars (US) of damage each year, and are leaving farmers in the developing world food insecure. Currently, all publically available transcriptome data for B. tabaci are generated from pooled samples, which can lead...

Background:Bemisia tabaci species ( B. tabaci ), or whiteflies, are the world’s most devastating insect pests. They cause billions of dollars (US) of damage each year, and are leaving farmers in the developing world food insecure. Currently, all publically available transcriptome data for B. tabaci are generated from pooled samples, which can lead...

Figure S2. Examples of accessions with attenuated symptoms and increased silencing over time.

Figure S3. CaLCuV AL1 frameshift mutation abolishes viral DNA replication in Nicotiana tabacum (NT1) protoplasts.

Figure S6. CaLCuV symptom score key.

Figure S4. New growth in Pla‐1 lacks TRV:AtPDS VIGS at later time points compared with Col‐0.

Figure S5. Pla‐1 is susceptible to TuMV.

Table S3. SNPs for Pla‐1 and Col‐0

Figure S1. Thumbnail images of CH‐42 VIGS in different Arabidopsis accessions.

Table S2. SSLP markers for Pla‐1 and Col‐0

Figure S7. QTL maps from F2:3 families.

Table S1. Response of 190 Arabidopsis accessions to inoculation with the CaLCuVA:CH‐42 VIGS vector or to CaLCuVA:LUC

Table S4. Candidate Genes for geminivirus immunity Pla‐1‐1 (gip‐1)

Methods S1. CaLCuV A DNA replication assay in Nicotiana tabacum (NT1) protoplasts. Methods S2. TuMV inoculation. Methods S3. QTL mapping using F2:3 families. Methods S4. Generation of the geminivirus immunity candidate gene list.

Cassava is the main staple food for over 800 million people globally. Its production in eastern Africa is being constrained by two devastating Ipomoviruses that cause cassava brown streak disease (CBSD); Cassava brown streak virus (CBSV) and Ugandan cassava brown streak virus (UCBSV), with up to 100% yield loss for smallholder farmers in the region...

111 cassava brown streak virus sequences downloaded from GenBank all with the highly conserved DAG motif in the coat protein. (PDF)

Weed-infecting begomoviruses play an important role in the epidemiology of crop diseases because they can potentially infect crops and contribute to the genetic diversity of crop-infecting begomoviruses. Despite the important epidemiological role that weed-infecting begomoviruses play, they remain insufficiently studied in Africa. Recently, we iden...

Geminiviruses are DNA viruses that cause severe crop losses in different parts of the world, and there is a need for genetic sources of resistance to help combat them. Arabidopsis has been used as a source for virus resistance genes that derive from alterations in essential host factors. We used a virus-induced gene silencing (VIGS) vector derived...

Illumina sequencing of RNA from a cassava cutting from northern Malawi produced a genome of Ugandan cassava brown streak virus (UCBSV-MW-NB7_2013). Sequence comparisons revealed stronger similarity to an isolate from nearby Tanzania (93.4% pairwise nucleotide identity) than to those previously reported from Malawi (86.9 to 87.0%).

Background Cassava brown streak disease is emerging as the most important viral disease of cassava in Africa, and is consequently a threat to food security. Two distinct species of the genus Ipomovirus (family Potyviridae) cause the disease: Cassava brown streak virus (CBSV) and Ugandan cassava brown streak virus (UCBSV). To understand the evolutio...

A novel bipartite legumovirus (genus Begomovirus, family Geminiviridae), that naturally infects the wild leguminous plant Desmodium sp. in Uganda, was molecularly characterized and named Desmodium mottle virus. The highest nucleotide identities for DNA-A, obtained from two field-collected samples, were 79.9% and 80.1% with the legumovirus, soybean...

Four isolates of a bipartite begomovirus from naturally infected Deinbollia borbonica plants exhibiting yellow mosaic symptoms in Kenya and Tanzania were molecularly characterised. The DNA-A was most closely related to that of tomato leaf curl Mayotte virus (AM701764; 82%), while the DNA-B shared the highest nucleotide sequence identity with that o...

The complete genomes of a monopartite begomovirus (genus Begomovirus, family Geminiviridae) and an associated betasatellite found infecting Vernonia amygdalina Delile (family Compositae) in Uganda were cloned and sequenced. Begomoviruses isolated from two samples showed the highest nucleotide sequence identity (73.1% and 73.2%) to an isolate of the...

Cassava is a major staple food for about 800 million people in the tropics and subGtropical regions of the world. Production of cassava is significantly hampered by cassava brown streak disease (CBSD), which is caused by Cassava brown streak virus (CBSV) and Ugandan cassava brown streak virus (UCBSV). The disease is suppressing cassava yields in ea...

Cassava is a major staple food for about 800 million people in the tropics and sub-tropical regions of the world. Production of cassava is significantly hampered by cassava brown streak disease (CBSD), caused by Cassava brown streak virus (CBSV) and Ugandan cassava brown streak virus (UCBSV). The disease is suppressing cassava yields in eastern Afr...

Importance: Cassava is a major crop in the developing world, with its production in Africa second only to maize. Cassava mosaic disease (CMD) is one of the most important diseases of cassava and a serious constraint to production across Africa. CMD2 is a major CMD resistance locus that has been deployed in many cassava cultivars through large scal...

Figure S1. Effect of time of harvesting (9, 12, 15 months after planting) on (A) fresh root yield (B) dry matter content (C) starch content (D) cyanide content, of six cassava landraces across three sites. Figure S2. GGE Scatter plot showing discrimination and representativeness of the environments (sites) using the starch yield data of the six ca...

High starch yield is the most important trait for commercialized cassava starch production. Furthermore, cyanide present in cassava roots poses a health challenge in the use of cassava for food. Cassava genotypes have varying maturity periods that are also environmental dependent. This study aimed at identifying suitable cultivars and optimum time...

A survey was conducted from April to May 2014 in 214 farmers' fields located across six major cassava-producing provinces (Western, Northwestern, Northern, Luapula, Lusaka, and Eastern) of Zambia to determine the status of cassava mosaic disease (CMD) and the species diversity of associated cassava mosaic geminiviruses (CMG). Mean CMD incidence var...

Cassava brown streak disease is caused by two devastating viruses, Cassava brown streak virus (CBSV) and Ugandan cassava brown streak virus (UCBSV) which are frequently found infecting cassava, one of sub-Saharan Africa's most important staple food crops. Each year these viruses cause losses of up to $100 million USD and can leave entire families w...

Cassava brown streak disease is caused by two devastating viruses, Cassava brown streak virus (CBSV) and Ugandan cassava brown streak virus (UCBSV) which are frequently found infecting cassava, one of sub-Saharan Africa’s most important staple food crops. Each year these viruses cause losses of up to $100 million USD and can leave entire families w...

Cassava mosaic disease (CMD) is caused by cassava mosaic begomoviruses (CMBs), which are transmitted by the whitefly (Bemisia tabaci) in sub-Saharan Africa. CMD and the pathogenic viruses associated with cassava were assessed in a country-wide survey in seven provinces of Zambia between April and May 2009. CMD incidence was highest in Northwestern...

A single-tube duplex and multiplex PCR was developed for the simultaneous detection of African cassava mosaic virus (ACMV), East African cassava mosaic Cameroon virus (EACMCV), East African cassava mosaic Malawi virus (EACMMV) and East African cassava mosaic Zanzibar virus (EACMZV), four cassava mosaic begomoviruses (CMBs) affecting cassava in sub-...

The genetic variability of whitefly (Bemisia tabaci) species, the vectors of cassava mosaic begomoviruses (CMBs) in cassava growing areas of Kenya, Tanzania, and Uganda, was investigated through comparison of partial sequences of the mitochondria cytochrome oxidase I (mtCOI) DNA in 2010/11. Two distinct species were obtained including sub-Saharan A...