Browsing by Author "Mangosongo, Hashim Mtulo"

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    Genetic diversity of the wild rice species (oryza ongistaminata) and gene flow between oryza longistaminata and the cultivated rice species (oryza sativa) in selected areas of Tanzania
    (University of Dar es Salaam, 2015) Mangosongo, Hashim Mtulo
    This study determined the extent and distribution of genetic diversity in natural populations of Oryza longistaminata from four selected districts of Tanzania through molecular and morphological characterization. The study also assessed the effects of soil physico-chemical parameters on the morphological characters of the species. In addition, the study assessed the potential for gene flow between O. longistaminata and selected varieties of O. sativa. Molecular or DNA-based evaluation of genetic diversity was carried out using microsatellites or SSR primers, in which twenty eight SSR primer pairs were used to evaluate genetic variation among 132 O. longistaminata accessions from the four study sites. Morphological characterization involved assessment of 140 individual O. longistaminata plants using morphological descriptors for wild and cultivated rice species. The effects of various soil physico-chemical parameters on the morphology of O. longistaminata were assessed using standard protocols and the extent of gene flow between O. longistaminata and selected varieties of O. sativa was assessed using nine SSR primer pairs. The results showed availability of high genetic diversity or variation among the O. longistaminata accessions in the study area and that the degree of genetic variation was higher within population than between populations. The study also revealed availability of high morphological variation among O. longistaminata populations and that the degree of morphological variation was related to soil physico-chemical parameters of the area. Moreover, the study revealed occurrence of natural gene flow between O. longistaminata and the two varieties of O. sativa and the gene flow occurs more frequently from O. sativa to O. longistaminata than from O. longistaminata to O. sativa, probably due to variation in breeding system and floral morphology between the two species. In the light of the findings of this study, there is urgent need for conservation of O. longistaminata in the study area, and that both in-situ and ex-situ conservation strategies are required in order to safeguard the genetic diversity of this species in Tanzania.