Browsing by Author "Kirimi, J.K."

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    Molecular and morphological characterization of preferred Kenyan multi-purpose pumpkin (cucurbita moschata duch.) cultivars
    (Chuka University, 2016) Kirimi, J.K.; Isutsa, D.K.; Nyende, A.B.; Nzuki, I.W.
    Pumpkin (C. moschata) is the most grown species, with a wide range of variability. Determining the degree of variability is the preliminary step in studying their genetic diversity. The objective of the present study was to characterize genotypically, compare the results with phenotypic data to establish correlations between their distances by classifying the accessions based on their dissimilarity. DNA extraction, polymerase chain reaction and Agarose Gel Electrophoresis (AGE) were done on 139 accessions using SSR and ISSR primers. Fluorescent capillary electrophoresis (CE) genotyping with labeled SSR was done on DNA samples of 96 selected accessions. Morphological characterization was done on-farm in a complete randomized design, replicated three times. Morphological data was subjected to analysis of variance using SAS. Means were separated at P=0.05. Chi square test (P=0.05) separated qualitative data. Unweighted Pair Group Method of arithmetic mean and Euclidean Genetic Distance constructed dendrograms using molecular and morphological data with XLstat. DNA quantity ranged from 70.02-2992 ng/µl and quality from 0.56-2.1 of 260/280 absorbance ratio. Molecular characterization with AGE revealed variations among accessions. Amplifications ranged 100-500 and 200-2000 bp, PIC 0.5 and 0.597, alleles number 526 and 509, polymorphism 21.3% and 74.01% in SSR and ISSR, respectively. CE revealed 23 alleles with a range of 181-326 bp. CE genotyping amplified 934 distinctive SSR DNA fragments. Mean PIC was 0.49, observed heterozygosity 0.5048, genotype number 6.8, gene diversity 0.5491 across the markers. Fluorescent SSRs had 98.54% mean polymorphism. CE revealed two unique alleles. Significant variations (P<0.05) resulted among 146 accessions morphologically with fruit ribbing being not significant. PCA provided 9 and 13 PCs for quantitative and qualitative data, respectively. Quantitative characters explained 82.37%, qualitative 71.54%, of total variation. Both morphological and molecular data revealed genetic diversity among accessions. The variation in Kenyan pumpkins is increasing hence there is need to conserve them to prevent genetic erosion through crossbreeding with exotic ones.