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Flamenco Beach Culebra Puerto Rico Refrigerator Magnet Quantification of cassava mosaic geminiviruses and cassava brown streak viruses
dc.contributor.advisor Labuschagne, Maryke T.
dc.contributor.advisor Gowda, Maruthi M.N.
dc.contributor.advisor Benesi, Ibrahim R. M.
dc.contributor.advisor Minnaar-Ontong, Adré
dc.contributor.author Musopole, Hastings Twalie
dc.description.abstract English: Cassava (Manihot esculanta Crantz) is a perennial woody plant which is cultivated in Africa, Asia and Latin America. It is tolerant to drought and grows in poor soils. It is a source of carbohydrates, vitamins and small quantities of proteins. In Malawi, it is the most important root crop and it is grown across the country. It is consumed as a staple food by 30% of the people living along the central and northern part of Lake Malawi. Its production is constrained by among others, diseases CMD and CBSD. These two diseases are known to spread through white flies. The magnitude of attack by the two diseases depends on the genotype and the environment. No released genotypes in Malawi have ever been evaluated in seed transmission of viruses’ studies. The experiment on the quantification of F1 cassava progenies from open pollinated F1 progeny crosses revealed that genotypes which show high severity of CMD are likely to allow rapid multiplication of EACMMV and SACMV. However, it has been proven that this might not always be the case as some genotypes may have higher virus quantities while showing slightly less severe symptoms. Genotypes which succumb to high disease symptom severity are likely to have high incidence of the disease. CMD symptom severity and incidence were positively correlated. The experiment on determination of virus quantities in different tissues has provided information that virus quantities in particular tissues depend on the cultivar used. The viruses can spread to all the tissues analysed in this research. It was shown that root parenchyma and leaf tissues accommodated most of CBSV and UCBSV in the cultivars used. When there was co-infection, CBSV and UCBSV were positively correlated. EACMMV and SACMV quantity can vary in cassava tissues depending on the cultivar. Leaves have shown to contain a relatively high quantity of the viruses. CBSV, UCBSV, EACMMV and SACMV symptoms were not observed in seedlings grown from seeds which were obtained from diseased plants. The virus species were also not detected using Real-time PCR. This suggests that these virus species are not transmitted from diseased plants through seeds. en_ZA
dc.description.abstract Afrikaans: Cassava (Manihot esculanta Crantz) is ‘n meerjarige houtagtige plant wat verbou word in Afrika, Asië en Latyns Amerika. Dit is droogte tolerant en kan groei in swak grond. Dit is ‘n bron van koolhidrate, vitamines en klein hoeveelhede proteïene. Dit is die belangrikste wortelgewas in Malawi, en dit groei oral in die land. Dit word as stapelvoedsel gebruik deur 30% van die mense wat woon langs die sentrale en noordelike dele van die Malawi meer. Cassava produksie word beperk deur, onder andere, die siektes CMD en CBSD. Hierdie twee siektes word versprei deur witvlieë. Die erns van die infeksie deur hierdie twee siektes hang af van die genotipe en die omgewing. Inligting oor die reaksie van verskillende Malawi genotipes en hulle nageslag aangaande akkumulasie van virusse, is baie beperk. Geen vrygestelde genotipes in Malawi is nog ooit geëvalueer vir saadoordrag van virusse nie. Die eksperiment oor die kwantifikasie van cassava F1 nageslag van oop en spesifieke kruisings het getoon dat genotipes met ‘n hoë vlak van CMD ‘n vinnige vermeerdering van SACMV toelaat. Dit is egter bewys dat dit nie altyd die geval is nie, omdat sekere genotipes groter hoeveelhede virus gehad het terwyl hulle steeds minder simptome getoon het; daar was dus geen korrelasie tussen min simptome van SACMV en CMD en virus insidensie nie. Genotipes wat baie siektesimptome gehad het egter hoë virus insidensie getoon; dus was die graad van die siekte met die insidensie gekorreleer. Die eksperiment vir die bepaling van virus hoeveelhede in verskillende weefseltipes het getoon dat virus hoeveelhede in spesifieke weefsel afhang van die cultivar wat gebruik is. Virusse het versprei na alle weefsel wat in die studie geanaliseer is. Wortel parenkiem weefsel het meeste van die CBSV en UCBSV in die cultivars gehuisves. Waar daar ko-infeksie was, was CBSV en UCBSV positief gekorreleer. SACMV hoeveelheid het gewissel tussen die wortel parenkiem, wortel korteks en stam korteks (5 cm van bo), afhangend van die cultivar. Blare het groot hoeveelhede virusse gehad. CBSV, UCBSV, EACMMV en SACMV simptome is nie gesien in saailinge wat van saad van siek plante ontwikkel is nie. Die virus spesies is ook nie met Real-time PCR gesien nie. Dit wys dat die virus spesies nie oorgdra is van siek plante deur saad nie. af
dc.subject Cassava -- Breeding en_ZA
dc.subject Cassava as food -- Malawi en_ZA
dc.subject Plant viruses en_ZA
dc.subject Cassava -- Diseases and pests en_ZA
dc.subject Thesis (Ph.D. (Plant Sciences: Plant Breeding))--University of the Free State, 2016 en_ZA
dc.title Quantification of cassava mosaic geminiviruses and cassava brown streak viruses en_ZA
Genetic linkage mapping of field resistance to cassava brown streak disease in cassava (Manihot esculenta Crantz) landraces from Tanzania ﻿