Browsing by Author "Nyende, A.B."

Now showing 1 - 3 of 3

Evaluation of Endogenous Phytocomponents and Amino Acids Associated with Direct Somatic Embryogenesis of Coffee (Coffea arabicaL.)
(Journal of Advances in Agriculture, 2022) Mayoli, R.N.; Isutsa, D.K.; Nyende, A.B.; Mweu, C.M.; ; ;
Coffee is one of the mostimportant cropscultivated in the world for use in beverages and confectionaries. Embryogenesis is a complex process that begins with a single cell and ends with the formation of mature embryos. Somatic embryo development involves accumulation of complex metabolites and storage reserves. This present experimentidentifiedandquantifiedendogenous phytocomponents and amino acidspresent during somatic embryogenesis of ‘Ruiru 11’.Laboratory experiments for this study were set up in the Coffee Research Institute, Kenyaat Ruiru.Third leaf pair explants were excised from 8-month-old greenhouse-grown mother plants sterilized and cultured in half strength Murashige and Skoog basal salts augmented with Thidiazuron. Once embryos had developed, the cultures were analysed for phytocomponents using GCMS andHPLC. The results showed that palmitoleic and stearic acids were highest (23.3 μg/g and 69.9 μg/g respectively) in brown embryogenic cultures. Cis 7,8 epoxy-2-methyl octadecane was highest(253μg/g) in green embryogenic cultures. (Z)-3-Tetradecene washighest(25 μg/g)in brown non-embryogenic cultures. Z,Z-3,13-Octadecedien-1-ol and (Z)-7-Hexadecenalwere highest (32.1 μg/g and 70.2 μg/g respectively) in green embryogenic cultures. Alanine content washighest (4.4μg/g) in embryos of brown cultures. Amino acids, fatty acids and their derivatives are potential biomarkers for embryogenesis.Other phytocomponentsshould be identified and their role in coffee somatic embryogenesis determined. Further studies regarding the status of the phytocomponentsidentified in the present study, especially in particular stages of embryo development are needed to propose treatments to improve coffee somatic embryo development.
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.
Relationships of Selected Endogenous Factors Associated with Direct Somatic Embryogenesis of Coffee (Coffea arabica L.)
(Journal of Advances In Agriculture, 2018-05-30) Mayoli, R.N.; Isutsa, D.K.; Nyende, A.B.; Mweu, C.M.; ; ;
Coffee is one of the most important cash crops produced in the world with great economic returns to growers and national gross domestic product. Somatic embryogenesis is a morphogenetic processes leading to plantlet regeneration and these processes are coupled with changes in the levels of primary metabolites. The present experiment established relationships of endogenous substances with direct somatic embryogenesis of coffee ‘Ruiru 11’. Laboratory experiments were set up at Coffee Research Institute, Ruiru-Kenya between 2014 and 2017. The set up was in a completely randomised design, replicated three times and repeated once. Third leaf pair explants were excised from 8-month-old greenhouse-grown mother plants and cultured in half strength Murashige and Skoog basal salts augmented with Thidiazuron. Once embryos had developed, the cultures were analysed for endogenous substances using HPLC and GCMS. Sucrose, phenolics, alkaloids, amino acids, fatty acids and their derivatives correlated positively, whereas fructose and glucose correlated negatively with the other biochemical components.Endogenous sucrose, chlorogenic acid, caffeine amino acid, fatty acids and their derivatives are potential biomarkers for coffee somatic embryogenesis, whereas endogenous fructose and glucose are inhibitors of the same. Further studies regarding the status of the biochemical components, especially in particular stages of embryo development should be conducted to establish treatments that can improve coffee direct somatic embryo development.