Browsing by Author "Nyende, A. B. 3"

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Fluorescent SSR Markers and Capillary Electrophoresis Reveal Significant Genetic Diversity in Naturalized Pumpkin Accessions in Kenya
(2017) Kiramana, J. K. 1; Isutsa, D. K. 1,2; Nyende, A. B. 3
This study was undertaken as a preliminary step in determining genetic diversity of naturalized pumpkins in Kenya. It entailed allelic patterns, frequency, inbreeding coefficient, molecular variance, cluster and inter-population genetic analyses. It utilized 96 pumpkin accessions and five fluorescent SSR markers in capillary electrophoresis. Data were captured using ABI 3730 software, and analyzed using GeneMapper V 4.1 software. Measures of genetic variability were determined using GenAlEx 6.5, genetic diversity within and among accessions using Power Marker V 3.25 and data contained in the electrophenograms by GeneMapper V 4.1 software. XLstat 2014 was used for cluster and GenAlEx 6.5 software for principal coordinates analyses. DNA quantity ranged from 62.7 to 2992 ng/µl and quality from 0.56 to 2.1 of 260/280 absorbance ratio. Fluorescent SSR markers detected 23 alleles with an average of 4.6 alleles per marker, with size ranging from 181 to 326 bp. A total of 934 distinct DNA fragments were identified. Mean PIC was 0.49, observed heterozygosity 0.5048, genotype number 6.8, gene diversity 0.5491, and polymorphism 98.5% across the markers. Mean allelic patterns showed great variation among the accessions. Cluster and principal coordinate analysis revealed distinct accession groups independent of their geographic origin. AMOVA indicated that genetic differentiation was significant (P=0.02). Total molecular diversity of 3% was attributed to regional differences, 9% to accession differences within regions, while 88% to differences within accessions. The FST of 0.026 indicated very little genetic differentiation due to continuous selection of pumpkin seeds by farmers. The present study proved that fluorescent SSR markers and capillary electrophoresis are effective in estimating genetic diversity and detecting polymorphisms present in pumpkin accessions in Kenya. The genetic diversity should be related with desirable quantitative and qualitative traits and used in improving pumpkin into commercial cultivars. The KK-3 and KK-56 accessions with unique, private and locally common alleles should be prioritised during conservation efforts.
Qualitative, Quantitative and Quality Variation of Naturalized Pumpkin Accessions in Mother and Baby Trials in Kenya
(2017) Kiramana, J. K. 1; Isutsa, D. K 1, 2; Nyende, A. B. 3
Pumpkin (Cucurbita moschata (Lam.) Poir.) is unsystematically produced in many tropical countries and development of standard cultivars using naturalised and adapted genetic resources has not yet been done. The present study evaluated naturalized pumpkin accessions yield in Kakamega, Embu and Nyeri in 2012 and 2013 and quality in Chuka in 2015 to identify superior ones that could be developed into commercial cultivars. The accessions were planted on-station in Kakamega and Embu for mother trials, on farmers’ farms in Kakamega and Nyeri for baby trials, and on-station in Chuka for TSS assessment. Mother and baby trials and quality assessment plants were spaced at 2mx2m in a completely randomised design. Qualitative and quantitative data were subjected to Chi-square analysis and ANOVA, respectively. Significant differences were separated using LSD test at P=0.05. The qualitative and quantitative traits measured were significant (P<0.05) and higher in local accessions compared to the control exotic ‘Sugar Baby’. The number of fruits per accession ranged from 1 to 9 in mother trials and 1 to 16 in baby trials. Accessions KK-40 and NY-154 produced highest 9 and 16 fruits, respectively, while NY-135, KK-21 and KK-22 produced 1 fruit each. Average fruit weight per plant was 4.2 kg for NY-130 and 0.2 kg for NY-77 in mother trials. Total fruit weight ranged from 0.2 to 15.9 kg in mother trials and 0.25 to 26.5 kg in baby trials. The highest 26.5 kg total fruit weight was for KK-30 in baby trials, and lowest 0.2 kg was for NY-77 in mother trials. Fruit firmness ranged from 3 to 10.2 kg/cm2 , while TSS ranged from 2.9 to 14% brix. Highest fruit firmness was 10.2 kg/cm2 for KK-9, while flesh firmness was 3 kg/cm2 for KK-46. Highest 14% brix was for KK-12 and KK-30, while lowest 2.9% brix was for KK-56. The significant and superior variation of naturalized pumpkin accessions in yield and quality, compared to the exotic ‘Sugar Baby’, presents material for selection and development into commercial, high value pumpkin production cultivars. The accessions perform better regardless of whether they are grown on-station or on-farm, meaning that what matters most is optimization of crop management practices. In this regard, KK-30 is recommended for selection and development into a standard cultivar, based on its highest yields and TSS.