Browsing by Author "Godfrey Sseremba"

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    Amplicon Sequencing Identified a Putative Pathogen, Macrophomina phaseolina, Causing Wilt in African Eggplant (Solanum aethiopicum) Grown in Tanzania and Uganda
    (Frontiers in Agronomy, 2024-01-03) Xiangming Xu; Ruth Minja; Elizabeth Balyejusa Kizito; Fekadu Dinssa; Greg Deakin; Pamela Nahamya Kabod; Asheri Kalala; Eliciana Kweka; Omary Mbwambo; Deusdedith Mbanzibwa; Hamza Msangi; Mildred Julian Nakanwagi; Tom Passey; Stuart Sentance; Godfrey Sseremba; Eleftheria Stavridou; Gerard J. Bishop
    African eggplant (Solanum aethiopicum L.) is one of the most common traditional vegetables in Tanzania and Uganda, but its productivity is severely affected by wilt diseases caused by a number of pathogens. Plant stem and root samples were collected in several fields from many neighboring diseased and healthy plants of the Gilo group in Tanzania and from the Shum group in Uganda to identify putative pathogens causing wilt on African eggplants. Through amplicon sequencing of sampled diseased and healthy tissues, we identified putative causal pathogens for the wilt symptoms. Wilting of S. aethiopicum in Uganda is most likely caused by the bacterial pathogen Ralstonia solanacearum whereas, in Tanzania, wilt is most likely caused by the fungal pathogen Macrophomina phaseolina, infecting roots. Infection of stems by Fusarium solani may also contribute to the wilt symptoms in Tanzania. Further artificial inoculation under controlled conditions confirmed that M. phaseolina can cause typical wilting symptoms on S. aethiopcium genotypes. The discovery of different putative causal agents of wilt in the crop demonstrates the need for site specific etiological analysis of wilt before developing and implementing effective control methods. Further research is needed to confirm the results and develop appropriate management measures against specific wilt pathogens.
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    Intraspecific crossability and compatibility within solanum aethiopicum
    (Elsevier Ltd, 2021-07) Ruth Buteme; Mary Nakajiri; Newton Kucel; Pamela Nahamya Kabod; Godfrey Sseremba; Elizabeth Balyejusa Kizito
    Understanding hybridization barriers is relevant for germplasm conservation and utilization. The prezygotic barriers to hybridization include floral morphological differences like pistil and stamen length, pollen characteristics and pollen-pistil interactions. This study sought to elucidate the reproductive biology of Solanum aethiopicum; its mating systems and compatibility barriers. Eight genotypes of Solanum aethiopicum were examined for differences in floral morphology, phenology and cross compatibility in a full diallel mating design, with assessment of fruit set, seed set and seed viability. In-vivo pollen tube growth was observed for failed crosses at 24, 48 and 72 h after pollination. All genotypes had heterostyly flowers, with predominantly small white petals. Incompatibility was observed in five out of 39 combinations. All selfed genotypes displayed compatibility implying the genotypes are self-compatible. Pollen–pistil incompatibility, which was exhibited in four out of the five failed cross combinations, occurred on the stigma, upper style and lower style, a phenomenon typical in Solanaceae. Solanum aethiopicum is self-compatible and majorly self-pollinating but has features that support cross-pollination.
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    Mode of Gene Action in Inheritance of Vegetative, Floral and Leaf Yield Traits in the African Eggplant (Solanum aethiopicum)
    (RUFORUM, 2021) Ruth Buteme; Nahamya Pamela Kabod; Godfrey Sseremba; Kizito Elizabeth Balyejusa
    Understanding gene actions and how they contribute in the expression of characters is of great importance when devising an efficient selection program through the use of a suitable mating design. This study sought to determine the mode of gene action involved in inheritance of vegetative and floral traits in Solanum aethiopicum. Specifically, to establish probable existence of dominance and combining ability of the studied S. aethiopicum genotypes. To do this, twenty-nine (29) successful hybrids from a partial diallel crossing design along with their parental lines were evaluated to determine the mode of gene action involved in inheritance of vegetative, floral and leaf yield traits of S. aethiopicum. A multivariate linear mixed model fit by REML was used to estimate variance components for general combining ability (GCA) and specific combining ability (SCA) in the incomplete diallele design. The specific combining ability (SCA) effects were significant (p>0.01) for all traits measured at 6 and 8 weeks after planting (WAP) except for Harvest Index. Broad-sense heritability (H2) values were generally high (>80%) for all traits compared to narrow sense heritability (h2) at both stages of harvest; moreover Baker’s ratio for these traits was low. The estimates of dominance variance were also higher in magnitude than corresponding estimates of additive variance. The cross N2xN14 had the highest SCA effects for majority of the vegetative traits and floral traits at both 6 and 8WAP. The results showed that non-additive gene action (dominant, additive × dominant and dominant dominant effects) takes centre stage in inheritance of petal colour, stem colour, relative style length, stem hairiness, plant height, number of leaves, plant canopy width, and stem girth, flowers per inflorescence and flowers per plant and harvest index. However, inheritance of leaf area is governed by additive gene action. Therefore, for improvement of the African eggplant, methods such as restricted recurrent selection in early segregating generations might be appropriate.