Browsing by Author "Ajanga, SI"

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    Internal Transcribed Spacer Primers Detect Better Ustilago kamerunensis; A Napier Grass Head Smut Pathogen Constraining The Dairy Sector In Eastern Africa
    (JAAS, 2014-09-30) Omayio, do; Ajanga, SI; Muoma, JV; MuyekhO, FN; Kariuki,I
    Two completely randomized glasshouse screening experiments in design coupled with two molecular screening assays were carried out at Kenya Agricultural Research Institute’s Muguga South and Trypanosomiasis Research Centres both located at 2095m above sea level at the (1o 13’ 53.0” S) and (36o 38’ 1.1” E) of Kiambu County in Kenya. The aim of the studies was to determine the efficacy of four different primer pairs in the detection of Ustilago kamerunensis in selected asymptomatic (non-smutting) napier grass accessions’ tissues at expected PCR band sizes and to investigate whether the selected accessions were completely resistant (immune) or tolerant to the pathogen. The glasshouse screening results revealed predominant differences in the smutting proportions of the accessions ranging from 0% to 90.22%. These differences were further manifested in the accession’s respective neighbour joining groups where a heterogeneous pattern in response to disease challenge was observed. The molecular screening assays demonstrated that internal transcribed spacer (1 / 4) primers were better in detecting the pathogen in the asymptomatic accessions’ tissues followed by β-tubulin (F1 / R2) primers at the expected band size. The molecular screening showed that ten out of eleven asymptomatic accessions and the four checks despite not smutting had the pathogen in their tissues with exception of accession 16806 which did not exhibit any in both molecular trials. The results indicated that the ten out of eleven selected asymptomatic accessions to head smut disease seemed tolerant and only 16806 seemed completely resistant (immune) to the napier head smut disease
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    Predicting Endophytes Contribution In vivo in Napier Grass Accessions’ tolerance against Ustilago kamerunensis Using In vitro Strategies
    (JAAS, 2014-10-30) Omayio, DO; Ajanga, SI; Muoma JV; Ochieno, DMW; Muyekho, FN; Mukoye, B; Leitich,RK
    Two completely randomized laboratory assays were carried out at the plant pathology section of the National Agricultural Research LaboratoriesKabete in Nairobi Kenya. The aim of the studies was to determine the abundance of endophytes among an initially selected and presumed tolerant napier grass accessions to head smut pathogen and to decipher their possible synergistic or individualistic contribution to the accessions asymptomatic response to the disease challenge. The analyzed Shannon diversity indices results indicated that the abundance of fungal endophytes was unequal with some exceptions. Moreover, low inhibition percentages were obtained of the morphotypes in dual cultures in vitro with the pathogen, besides most of their interactions favouring the luxurious growth of the pathogen. Therefore, direct role of the endophytes to the tolerance of the accessions seems nonexistent if not minimal. However, heightened hormonal secretions like auxins by the crop need to be investigated to determine whether the endophytes are enhancing its production to enable the plants tolerate the pathogen damage through compensatory growth strategies
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    Using Napier grass accessions' origins, neighbour joining groups their responses to Ustilago kamerunensis to predict a probable evolutionary scenario
    (IJRSR, 2015-02) Omayio, DO.; Ajanga, SI; Muoma, JV; Muyekho, FN.; Yamame, MK.; Kariuki, I; Mwendia, S
    Prediction of a possible co-evolutionary process is critical in a plant-pathogen interactionbasing on a host plant’s origin, its molecular characteristics and involved pathogen’s history. Therefore, two successive screening experiments in completely randomized design were set up at Muguga-south glasshouses in Kenya. The study objective was to determine whether the resistant napier grass accessions exhibited any indications of selection preference to origin as may have been influenced by the African pathogen. Smutted tiller numbers and subsequentlyproportions of smutting among the accessions were determined to enable the within and across evaluation of the accessions’ neighbour joining groups. The accessions exhibited observable differences with 67.9% and 32.1% smutting and not smutting respectively. Further, on across evaluation of the respective groups; the Southern Africa neighbour joining group had the most asymptomatic accessions at 35.29% whereas the USA 1 and 2 had the least at 5.88%. Onwithin the groups’ evaluation, the Southern Africa and USA 2 had the highest and least relative resistance indices of 0.2900 and -1.2606 respectively. Whereas, for the relative susceptibility indices the USA 2 had the highest and Southern Africa group the least at 0.2940and -0.1732 respectively. The results suggest that resistance trait selection preference seems tobe skewed towards accessions whose origin is from Africa especially south of Africa where the grass traces its origin at the Zambezi valley.