Screening for Resistance in Farmer-Preferred Cassava Cultivars from Ghana to a Mixed Infection of CBSV and UCBSV

Elegba, Wilfred; Gruissem, Wilhelm; Vanderschuren, Hervé

doi:10.3390/plants9081026

Cited by 14 publications

(6 citation statements)

References 52 publications

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“…We therefore assume a constant distribution of cassava production across Uganda over time. We also assume that all cassava is equally susceptible to infection by CBSIs, which is consistent with currently available evidence [30,31]. Similarly, evidence to date does not indicate major differences in either the yield impact or geographic distribution of the two CBSIs [32].…”

Section: Discussionsupporting

confidence: 85%

Developing a predictive model for an emerging epidemic on cassava in sub-Saharan Africa

Godding

Stutt

Alicai

et al. 2022

Preprint

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The agricultural productivity of smallholder farmers in sub-Saharan Africa (SSA) is severely constrained by pests and pathogens, impacting economic stability and food security. Since 2004, an epidemic of cassava brown streak disease (CBSD) has been spreading rapidly from Uganda, with the disease causing necrosis of the edible root tissue. Based on sparse surveillance data, the epidemic front is currently believed to be at least as far west as central DRC and as far south as Zambia. The DRC is the world’s highest per capita consumer of cassava and future spread threatens production in West Africa which includes Nigeria, the world’s largest producer of cassava. Here, we take a unique Ugandan CBSD surveillance dataset spanning 2004 to 2017 and develop, parameterise, and validate a landscape-scale, spatiotemporal epidemic model of CBSD at a 1 km2 resolution. While this paper focuses on Uganda, the model is designed to be readily extended to make predictions beyond Uganda for all 32 major cassava producing countries of SSA, laying the foundations for a tool capable of informing strategic policy decisions at a national and regional scale.

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Section: Discussionsupporting

confidence: 85%

Developing a predictive model for an emerging epidemic on cassava in sub-Saharan Africa

Godding

Stutt

Alicai

et al. 2022

Preprint

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“…This magnitude of CBSD severity can be attributed to a lack of CBSD resistance alleles in the Nigerian germplasm. A similar outcome was noted by Elegba et al (2020) , who reported less than 50% survival rate for Ghanaian cassava genotypes tested against CBSV and UCBSV under screen-house conditions. Likewise, Winter et al (2019) reported moderate to severe foliar symptoms when 238 South American cassava genotypes were assessed for resistance to CBSVs.…”

Section: Discussionsupporting

confidence: 81%

Cassava Brown Streak Disease Response and Association With Agronomic Traits in Elite Nigerian Cassava Cultivars

et al. 2021

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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 (CBSDrs) (0.71) and CBSD6i (0.5). Positive and highly significant correlations were noted between CBSD root incidence (CBSDri) and CBSDrs (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 CBSDrs (r = 0.35***). Fresh root weight (FreshRW) negatively correlated with CBSDri and CBSDrs, 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.

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“…We selected 11 cassava cultivars or landraces popular with farmers in Ghana ( Table 1 ). These cultivars have varying degrees of susceptibility to CMD and CBSD ( Elegba et al, 2020 ). We screened the selected cultivars for production of OES, a critical initial step required for the induction of FEC and subsequent genetic transformation.…”

Section: Resultsmentioning

confidence: 99%

Efficient Genetic Transformation and Regeneration of a Farmer-Preferred Cassava Cultivar From Ghana

et al. 2021

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Cassava is an important staple crop that provides food and income for about 700 million Africans. Cassava productivity in Africa is limited by viral diseases, mainly cassava mosaic disease (CMD) and cassava brown streak disease (CBSD). Genetic barriers such as high heterozygosity, allopolyploidy, poor seed set, and irregular flowering constrain the development of virus-resistant cassava varieties via conventional breeding. Genetic transformation represents a valuable tool to circumvent several challenges associated with the development of virus resistance and other valuable agronomic traits in cassava. The implementation of genetic transformation in many local African cultivars is limited either by the difficulty to produce friable embryogenic callus (FEC), low transformation, and/or regeneration efficiencies. Here, we report the successful induction of organized embryogenic structures (OES) in 11 farmer-preferred cultivars locally grown in Ghana. The production of high quality FEC from one local cultivar, ADI 001, facilitated its genetic transformation with high shoot regeneration and selection efficiency, comparable to the model cassava cultivar 60444. We show that using flow cytometry for analysis of nuclear ploidy in FEC tissues prior to genetic transformation ensures the selection of genetically uniform FEC tissue for transformation. The high percentage of single insertion events in transgenic lines indicates the suitability of the ADI 001 cultivar for the introduction of virus resistance and other useful agronomic traits into the farmer-preferred cassava germplasm in Ghana and Africa.

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Screening for Resistance in Farmer-Preferred Cassava Cultivars from Ghana to a Mixed Infection of CBSV and UCBSV

Cited by 14 publications

References 52 publications

Developing a predictive model for an emerging epidemic on cassava in sub-Saharan Africa

Developing a predictive model for an emerging epidemic on cassava in sub-Saharan Africa

Cassava Brown Streak Disease Response and Association With Agronomic Traits in Elite Nigerian Cassava Cultivars

Efficient Genetic Transformation and Regeneration of a Farmer-Preferred Cassava Cultivar From Ghana

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