Browsing by Author "Bramwel W. Wanjala"

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    Genetic diversity in Napier grass (Pennisetum purpureum) cultivars: implications for breeding and conservation
    (Journal for Plant Science, 2013-10-30) Bramwel W. Wanjala; Meshack Obonyo; Francis N. Wachira; Alice Muchugi; Margaret Mulaa; Jagger Harvey; Robert A. Skilton; Janice Proud; Jean Hanson
    Napier grass is an important forage crop for dairy production in the tropics; as such, its existing genetic diversity needs to be assessed for conservation. The current study assessed the genetic variation of Napier grass col lections from selected regions in Eastern Africa and the International Livestock Research Institute Forage Germplasm Ethiopia. The diversity of 281 cultivars was investigated using five selective amplified fragment length polymorphism (AFLP) markers and classical population genetic parameters analysed using various software. The number of bands generated was 216 with fragments per primer set ranging from 50 to 115. Mean percentage polymorphic loci was 63.40. Genetic diversity coefficients based on Nei’s genetic diversity ranged from 0.0783 to 0.2142 and Shannon’s in formation index ranged from 0.1293 to 0.3445. The Fst value obtained was moderately significant (Fst ¼ 0.1688). Neighbour-joining analysis gave two distinct clusters which did not reflect geographical locations. Analysis of molecu lar variance showed all variance components to be highly significant (P , 0.001), indicating more variation within (91 %) than between populations (9 %). Results suggested moderate genetic differentiation among Napier grass popu lations sampled, which could imply a high germplasm exchange within the region. The AFLP markers used in this study efficiently discriminate among cultivars and could be useful in identification and germplasm conservation.
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    Genetic Diversity of Kenyan Native Oyster Mushroom (Pleurotus)
    (Taylor & Francis Online, 2017-01-20) Ojwang D. Otieno; Calvin Onyango; Justus Mungare Onguso; Lexa G. Matasyoh; Bramwel W. Wanjala; Mark Wamalwa; Jagger J.W. Harvey
    Members of the genus Pleurotus, also commonly known as oyster mushroom, are well known for their socioeconomic and biotechnological potentials. Despite being one of the most important edible fungi, the scarce information about the genetic diversity of the species in natural populations has limited their sustainable utilization. A total of 71 isolates of Pleurotus species were collected from three natural populations: 25 isolates were obtained from Kakamega forest, 34 isolates from Arabuko Sokoke forest and 12 isolates from Mount Kenya forest. Amplified fragment length polymorphism (AFLP) was applied to thirteen isolates of locally grown Pleurotus species obtained from laboratory samples using five primer pair combinations. AFLP markers and internal transcribed spacer (ITS) sequences of the ribosomal DNA were used to estimate the genetic diversity and evaluate phylogenetic relationships, respectively, among and within populations. The five primer pair combinations generated 293 polymorphic loci across the 84 isolates. The mean genetic diversity among the populations was 0.25 with the population from Arabuko Sokoke having higher (0.27) diversity estimates compared to Mount Kenya population (0.24). Diversity between the isolates from the natural population (0.25) and commercial cultivars (0.24) did not differ significantly. However, diversity was greater within (89%; P > 0.001) populations than among populations. Homology search analysis against the GenBank database using 16 rDNA ITS sequences randomly selected from the two clades of AFLP dendrogram revealed three mushroom species: P. djamor, P. floridanus and P. sapidus; the three mushrooms form part of the diversity of Pleurotus species in Kenya. The broad diversity within the Kenyan Pleurotus species suggests the possibility of obtaining native strains suitable for commercial cultivation.