Simple sequence repeat (ssr) genetic analysis of cassava mosaic disease resistance in selected f1 populations of cassava

Project Abstract

<p> Cassava mosaic disease caused by begomoviruses is the most widespread disease of cassava<br>in Africa. Simple sequence repeat (SSR) genetic analysis of an F1 population of cassava was<br>carried out to identify new sources of CMD resistance. Genomic DNA extracted from parents<br>and progeny was amplified using polymerase chain reaction (PCR).The broad objective of the study was to investigate the socio-economic and<br>cultural dimensions of food security among selected ethnic groups in North Central<br>Nigeria. Specifically, the study was designed to determine food culture and practices of<br>the respondents; determine the household food security status (energy availability) across<br>ethnic groups; determine dietary diversity of the households across cultures; identify<br>perceived constraints militating against household food security; and describe the coping<br>strategies utilized by the households during food shortages. Seven hypotheses and a<br>conceptual framework were developed for the study. The population of the study consists<br>of all ethnic groups in North Central Nigeria. The zone comprises about 60 ethnic groups.<br>Specifically, the study was carried out among Tiv, Igala and Eggon ethnic groups of<br>Benue, Kogi and Nasarawa States. A multi-stage sampling technique was adopted for the<br>study. Three ethnic groups (Tiv, Igala and Eggon) and one village per ethnic group PCR amplifications were<br>run on polyacrylamide and agarose gels. SSR marker technology was used to identify markers<br>linked to CMD resistance via bulk segregant analysis (BSA).<br>One hundred and forty<br>molecular markers from the International Center for Tropical Agriculture (CIAT) were used<br>to screen the parents, contrasting bulks and the individuals that make up the contrasting bulks.<br>The bulk segregant analysis produced forty polymorphic markers. Screening of the<br>contrasting individuals with the polymorphic markers revealed four candidate markers (SSRY<br>238, SSRY 51, SSRY 76 and SSRY 20) linked to CMD resistance. The correlation coefficient<br>values between genotypic and phenotypic data classes for candidate markers were generally<br>low. The t-test value between both genotypic classes (absence of band versus presence of<br>band) were not significant (P&gt;0.05) in each of the four markers. The results from this study<br>suggest that there are at least two new CMD resistance genes in the mapping population. <br></p>

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