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

2021 ◽  
Vol 12 ◽  
Author(s):  
Chukwuka Ugochukwu Ano ◽  
Mildred Ochwo-Ssemakula ◽  
Angele Ibanda ◽  
Alfred Ozimati ◽  
Paul Gibson ◽  
...  
Keyword(s):  
Southern Africa ◽  
Agronomic Traits ◽  
Selection Index ◽  
Mosaic Disease ◽  
Cassava Mosaic Disease ◽  
Root Weight ◽  
Cassava Brown Streak Disease ◽  
Cassava Production ◽  
Eastern And Southern Africa ◽  
Brown Streak

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.

scholarly journals Influence of Abiotic Factors on the Population of Serangium Parcesetosum; A Predator of Cassava Whitefly in Uganda

2019 ◽  
pp. 31-37
Author(s):  
Wamani S. ◽  
Acipa A. ◽  
Opio M. S. ◽  
Ocitti P. ◽  
Wanyana B. ◽  
...  
Keyword(s):  
Production Systems ◽  
Abiotic Factors ◽  
Mosaic Disease ◽  
Cassava Mosaic Disease ◽  
Predator Population ◽  
Ecological Zones ◽  
Serangium Parcesetosum ◽  
Field Situation ◽  
Cassava Brown Streak Disease ◽  
Cassava Production

Whitefly is a known pest of economic importance in the cassava production systems of Africa. This pest has been reported to cause losses to cassava through direct feeding damage as well as vectoring cassava mosaic disease (CMD) and cassava brown streak disease (CBSD). Serangium parcesetosum is a known predator of whitefly (Bemisia tabaci) and previous screenhouse and laboratory studies reported that temperature affected the reproduction and survival of this predator. However, these findings lacked precision since they did not depict the field situation. In that regard, it was imperative to initiate a study to help understand the influence of abiotic factors especially temperature and rainfall on the population of S. parcesetosum in the cassava growing fields of Uganda. The study was conducted in two agro-ecological zones of Uganda, namely; North Western Savannah Grassland (Lira) and the Kyoga Plains (Kamuli) in the first rains of 2017. Results revealed that temperature caused an increment of 3.5%, 9.1% (Kamuli) and 1.1%, 1.8% (Lira) for mean adult and larvae S. parcesesotum per plant respectively. On the contrary, rainfall caused a decrease in the population of S. parcesesotum in Lira. Generally, the effect of both temperature and rainfall on the predator population in the field was minimal.

scholarly journals Genetic Diversity of Mitochondrial DNA of Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) Associated with Cassava and the Occurrence of Cassava Mosaic Disease in Zambia

Insects ◽  
2020 ◽  
Vol 11 (11) ◽  
pp. 761
Author(s):  
Patrick Chiza Chikoti ◽  
Mathias Tembo ◽  
James Peter Legg ◽  
Rudolph Rufini Shirima ◽  
Habibu Mugerwa ◽  
...  
Keyword(s):  
Bemisia Tabaci ◽  
Control Strategies ◽  
Mosaic Disease ◽  
Sub Saharan Africa ◽  
Cassava Mosaic Disease ◽  
Northern Province ◽  
Western Province ◽  
Key Factor ◽  
Sub Saharan ◽  
Brown Streak

Bemisia tabaci is an important vector of cassava brown streak viruses and cassava mosaic begomoviruses, the causal agents of cassava brown streak disease and cassava mosaic disease (CMD), respectively. A study was carried out to determine the genetic variability of B. tabaci associated with cassava and the occurrence of CMD in Zambia in 2013 and 2015. Phylogenetic analysis showed the presence of only the sub-Saharan Africa 1 (SSA1) genetic group in Zambia. The SSA1 population had three population subgroups (SGs): SSA1-SG1, SSA1-SG2 and SSA1-SG3. All three SSA1 population subgroups occurred in Western Province. However, only SSA1-SG3 occurred in Eastern Province, while only SSA1-SG1 occurred in North Western and Luapula Provinces. Adult B. tabaci were most abundant in Western Province in 2013 (11.1/plant) and 2015 (10.8/plant), and least abundant (0.2/plant) in Northern Province in both 2013 and 2015. CMD was prevalent in all seven provinces surveyed, with the highest incidence recorded in Lusaka Province in both 2013 (78%) and 2015 (83.6%), and the lowest in Northern Province in both 2013 (26.6%) and 2015 (29.3%). Although SSA1-SG1 occurred at greater abundances than the other subgroups, there was no direct association demonstrated between whitefly subgroup and incidence of CMD. Establishing which B. tabaci genetic groups and populations are associated with CMD and their distribution in the country is a key factor in guiding the development of CMD control strategies for cassava-dependent households.

scholarly journals Optical Imaging Method for Determining Symptoms Severity of Cassava Mosaic Disease

2015 ◽  
Vol 7 (6) ◽  
pp. 34
Author(s):  
Benjamin Anderson ◽  
Moses Jojo Eghan ◽  
Elvis Asare-Bediako ◽  
Paul Kingsley Buah-Bassuah
Keyword(s):  
Clustering Algorithm ◽  
Mosaic Disease ◽  
Cassava Mosaic Disease ◽  
Imaging Method ◽  
Total Leaf Area ◽  
Actual Surface ◽  
Cassava Leaves ◽  
Major Constraint ◽  
Cassava Production

<p class="1Body">Cassava mosaic disease (CMD) is a major constraint to cassava production in cassava growing regions<strong>.</strong> Severity of CMD symptoms on cassava leaves is usually assessed visually using an arbitrary scale, which is semi-qualitative, and does not represent the actual surface area of diseased leaf. The objective of this study was to develop a quantitative method of assessing the severity of CMD. A combination of polarimeteric digital colour images, L*a*b* colour model and <em>K</em>-means clustering algorithm were used to determine the areas of CMD symptoms and healthy areas on leaves. The severity of CMD on a leaf is determined by computing the percentage of the CMD symptomatic area to the total leaf area. The analysis provides relatively fast and accurate classification of Cassava mosaic diseased leaves. The proposed method will enable plant scientists to obtain accurate and reliable data, forming the basis for better decision making.</p>

scholarly journals Re-emergence of Cassava Brown Streak Disease in Uganda

Plant Disease ◽  
2007 ◽  
Vol 91 (1) ◽  
pp. 24-29 ◽  
Author(s):  
T. Alicai ◽  
C. A. Omongo ◽  
M. N. Maruthi ◽  
R. J. Hillocks ◽  
Y. Baguma ◽  
...  
Keyword(s):  
Amino Acid ◽  
Amino Acid Identity ◽  
Cassava Mosaic Disease ◽  
Streak Virus ◽  
Sequence Comparisons ◽  
Acid Identity ◽  
Cp Gene ◽  
Cassava Brown Streak Virus ◽  
Cassava Brown Streak Disease ◽  
Brown Streak

During November 2004, veinal chlorosis on mature cassava leaves, typical of cassava brown streak disease (CBSD), was observed at Mukono in central Uganda. Five out of 11 cultivars at the site showed CBSD symptoms (incidence range 4 to 64%). In a survey of farmers' fields, CBSD was observed in Wakiso and Mukono districts. Incidence of cassava mosaic disease was also recorded and averaged 60% for landraces (range 16.7 to 100%) and 20% for resistant varieties (range 0 to 65%). Leaf samples of plants with CBSD symptoms produced an amplicon of 222 bp using reverse transcription-polymerase chain reaction with primers that amplify a fragment of the coat protein (CP) gene of Cassava brown streak virus. Sequence comparisons based on the amplified CP gene fragment indicated that the isolates have 77 to 82.9% nucleotide and 43.9 to 56.8% amino acid identity with those from Mozambique and Tanzania. There was 95.9 to 99.5% nucleotide and 85.1 to 90.5% amino acid identity among the Ugandan isolates. These results confirm the re-emergence of CBSD in Uganda after it was first observed in the 1930s in cassava introduced from Tanzania and controlled by eradication. Prior to this report, CBSD was known to be restricted to the coastal lowlands of East Africa.

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

2021 ◽  
Vol 12 ◽  
Author(s):  
Wilfred Elegba ◽  
Emily McCallum ◽  
Wilhelm Gruissem ◽  
Hervé Vanderschuren
Keyword(s):  
Genetic Transformation ◽  
Virus Resistance ◽  
Agronomic Traits ◽  
Mosaic Disease ◽  
Cassava Mosaic Disease ◽  
Local Cultivar ◽  
Friable Embryogenic Callus ◽  
Genetic Barriers ◽  
Successful Induction ◽  
Transgenic Lines

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.

scholarly journals Field Evaluation of Some Cassava Cultivars against the African Cassava Mosaic Disease in the Humid Forests of Cameroon

2019 ◽  
pp. 1-8
Author(s):  
A. Mogo ◽  
J. Fomekong Nopogwo ◽  
E. L. Ngonkeu Mangaptche ◽  
R. Ghogomu Tamouh ◽  
E. Temgoua ◽  
...  
Keyword(s):  
Large Scale ◽  
Block Design ◽  
Field Evaluation ◽  
Mosaic Disease ◽  
Annual Production ◽  
Cassava Mosaic Disease ◽  
Yield Performance ◽  
Randomized Complete Block Design ◽  
Cassava Production ◽  
Improved Cultivars

There is a considerable deficit in the annual production of cassava in Cameroon of about 31 million tons, and this has been mainly due to constraints related to pest attacks and most especially diseases like the African Cassava Mosaic Disease (ACMD). This study was therefore undertaken on three sites in the locality of Bityili (South Region of Cameroon), to determine amongst improved and local cassava cultivars those that provide resistance to the development of the ACMD. The severity and incidence of this disease was evaluated and its impact on cassava yield. In each site, cassava was grown in a randomized complete block design. The local cultivars (Ekobele and Ngon kribi) showed higher severity (76-100%) and incidence of ACMD compared to the improved cultivars (TMS 92/0326 and TMS 96/1414) of 0-25% and 0-10%, respectively. Strong inverse correlations were observed between ACMD severity and yield performance, measured in terms of number of tubers/plant and weight of fresh tubers. The improved cultivars, TMS 92/0326 and TMS 96/1414, could, therefore, be recommended for large-scale planting in a bid to promote cassava production in the South Region of Cameroon.

scholarly journals Evaluation of Resistance of Cassava Half-Sib Progenies to Cassava Mosaic Disease and Their Agronomic Performances in Western Kenya

2018 ◽  
Vol 10 (12) ◽  
pp. 78
Author(s):  
Eric Mpongolo Musungayi ◽  
Kahiu Ngugi ◽  
James Wanjohi Muthomi ◽  
Vincent Woyengo Were ◽  
Florence Mmogi Olubayo ◽  
...  
Keyword(s):  
Agronomic Traits ◽  
Matter Content ◽  
Mosaic Disease ◽  
Control Measures ◽  
High Yield ◽  
Cassava Mosaic Disease ◽  
Dry Matter Content ◽  
Root Yield ◽  
Western Kenya ◽  
Sib Families

Cassava mosaic disease (CMD) caused by Bemisia tabaci is among the major contributors to low cassava yield in Africa and therefore requires instituting control measures. Due to genetic diversity in cassava, only clones with superior agronomic traits, disease resistance and high yield are selected and released to farmers or deployed in breeding program. This study was conducted to evaluate the resistance of cassava half-sib families to CMD. Field trials were conducted at Kenya Agricultural and Livestock Research Organization (KALRO), at Kakamega and Alupe research stations in western Kenya from June 2016 to June 2017. Sixty progenies were compared to that of their five parents by planting cuttings in 4 &times; 2 meters plots. Data were collected on plant height, number of roots per plant, harvest index, root yield, dry matter content, cassava mosaic disease and whiteflies infestation. Twenty three genotypes had a mean score of 1.0 to CMD, implying that they are resistant. Cassava grown at Alupe was observed to have high number of susceptible genotypes compared to cassava grown at Kakamega, indicating the effect of the environment on the genotypes. Parental genotypes, Kaleso and MM96/4271 presented high number of progenies showing CMD resistance. Genotypes, P4G1 and P2G3 with mean root yield of 31.6 t ha-1 and 30.0 t ha-1 were the highest yielding in term of root yield. A number of half-sib families generated from MM96/4271, Kaleso and MM96/0686 performed well with respect to yield recorded on their respective parents. Evaluation of new cassava varieties under local disease conditions would most likely improve the productivity of cassava through selection of resistant clones.

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