Browsing by Author "Mutiga, S.K."
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Item Foliar Diseases and the Associated Fungi in Rice Cultivated in Kenya(MDPI, 2022-05-07) Nganga, E.M.; Kyallo, M.; Orwa, P.; Rotich, F.; Gichuhi, E.; Kimani, J.M.; Mwongera, D.; Waweru, B.; Sikuku, P.; Musyimi, D.M.; Mutiga, S.K.; Ziyomo, C.; Murori, R.; Wasilwa, L.; Correll, J.C.; Talbot, N.J.; Maseno University ; -International Livestock Research Institute ; University of Embu ; Kenya Agricultural and Livestock Research Organization ; International Rice Research Institute ; The University of Arkansas System ; University of East AngliaWe conducted a survey to assess the occurrence and severity of rice blast and brown spot diseases on popular cultivars grown in the Busia, Kirinyaga, and Kisumu counties of Kenya in 2019. Working with agricultural extension workers within rice production areas, we interviewed farmers (n = 89) regarding their preferred cultivars and their awareness of blast disease, as this was the major focus of our research. We scored the symptoms of blast and brown spot and assessed the lodging, plant height, and maturity of the crops (days after planting). Furthermore, we collected leaf and neck tissues for the assessment of the prevailing fungal populations. We used specific DNA primers to screen for the prevalence of the causal pathogens of blast, Magnaporthe oryzae, and brown spot, Cochliobolus miyabeanus, on asymptomatic and symptomatic leaf samples. We also conducted fungal isolations and PCR-sequencing to identify the fungal species in these tissues. Busia and Kisumu had a higher diversity of cultivars compared to Kirinyaga. The aromatic Pishori (NIBAM 11) was preferred and widely grown for commercial purposes in Kirinyaga, where 86% of Kenyan rice is produced. NIBAM108 (IR2793-80-1) and BW196 (NIBAM 109) were moderately resistant to blast, while NIBAM110 (ITA310) and Vietnam were susceptible. All the cultivars were susceptible to brown spot except for KEH10005 (Arize Tej Gold), a commercial hybrid cultivar. We also identified diverse pathogenic and non-pathogenic fungi, with a high incidence of Nigrospora oryzae, in the rice fields of Kirinyaga. There was a marginal correlation between disease severity/incidence and the occurrence of causal pathogens. This study provides evidence of the need to strengthen pathogen surveillance through retraining agricultural extension agents and to breed for blast and brown spot resistance in popular rice cultivars in Kenya.Item Integrated Strategies for Durable Rice Blast Resistance in Sub-Saharan Africa(APS Publications, 2021-11-23) Mutiga, S.K.; Rotich, F.; Were, V.M.; Kimani, J.K.; Mwongera, D.T.; Mgonja, E.; Onaga, G.; Konat, K.; Razanaboahirana, C.; Bigirimana, J.; Ndayiragije, A.; Gichuhi, E.; Yanoria,M.J.; Otipa, M.; Wasilwa, L.; Ouedraogo, I.; Mitchell, T.; Guo-Liang, W.; Correll, J.C.; Talbot, N.J.; International Livestock Research Institute (BecA-ILRI) ; University of Arkansas ; University of Embu ; University of East Anglia ; Kenya Agricultural and Livestock Research Organization (KALRO) ; Tanzania Agricultural Research Institute ; National Agricultural Research Organization ; Institute of Environment and Agricultural Research ; Institute Polytechnique Unilasalle ; International Rice Research Institute (IRRI) ; The Ohio State UniversityRice is a key food security crop in Africa. The importance of rice has led to increasing country-specific, regional, and multinational efforts to develop germplasm and policy initiatives to boost production for a more food-secure continent. Currently, this critically important cereal crop is predominantly cultivated by small-scale farmers under suboptimal conditions in most parts of sub-Saharan Africa (SSA). Rice blast disease, caused by the fungus Magnaporthe oryzae, represents one of the major biotic constraints to rice production under small-scale farming systems of Africa, and developing durable disease resistance is therefore of critical importance. In this review, we provide an overview of the major advances by a multinational collaborative research effort to enhance sustainable rice production across SSA and how it is affected by advances in regional policy. As part of the multinational effort, we highlight the importance of joint international partnerships in tackling multiple crop production constraints through integrated research and outreach programs. More specifically, we highlight recent progress in establishing international networks for rice blast disease surveillance, farmer engagement, monitoring pathogen virulence spectra, and the establishment of regionally based blast resistance breeding programs. To develop blast-resistant, high yielding rice varieties for Africa, we have established a breeding pipeline that utilizes real-time data of pathogen diversity and virulence spectra, to identify major and minor blast resistance genes for introgression into locally adapted rice cultivars. In addition, the project has developed a package to support sustainable rice production through regular stakeholder engagement, training of agricultural extension officers, and establishment of plant clinics.Item Multiple Mycotoxins in Kenyan Rice(MDPI, 2021-03-11) Mutiga, S.K.; Mutuku, J.M.; Koskei, V.; Gitau, J.K.; Ng’ang’a, F.; Musyoka, J.; Chemining’wa, G.N.; Murori, R.; International Livestock Research Institute (BecA-ILRI) Hub ; University of Arkansas, Fayetteville, AR 72701, USA; National Irrigation Authority (NIA); University of Nairobi ; International Rice Research Institute, Eastern and Southern AfricanMultiple mycotoxins were tested in milled rice samples (n = 200) from traders at different milling points within the Mwea Irrigation Scheme in Kenya. Traders provided the names of the cultivar, village where paddy was cultivated, sampling locality, miller, and month of paddy harvest between 2018 and 2019. Aflatoxin, citrinin, fumonisin, ochratoxin A, diacetoxyscirpenol, T2, HT2, and sterigmatocystin were analyzed using ultra-high-performance liquid chromatography–tandem mass spectrometry (UHPLC–MS/MS). Deoxynivalenol was tested using enzyme-linked immunosorbent assay (ELISA). Mycotoxins occurred in ranges and frequencies in the following order: sterigmatocystin (0–7 ppb; 74.5%), aflatoxin (0–993 ppb; 55.5%), citrinin (0–9 ppb; 55.5%), ochratoxin A (0–110 ppb; 30%), fumonisin (0–76 ppb; 26%), diacetoxyscirpenol (0–24 ppb; 20.5%), and combined HT2 + T2 (0–62 ppb; 14.5%), and deoxynivalenol was detected in only one sample at 510 ppb. Overall, low amounts of toxins were observed in rice with a low frequency of samples above the regulatory limits for aflatoxin, 13.5%; ochratoxin A, 6%; and HT2 + T2, 0.5%. The maximum co-contamination was for 3.5% samples with six toxins in different combinations. The rice cultivar, paddy environment, time of harvest, and millers influenced the occurrence of different mycotoxins. There is a need to establish integrated approaches for the mitigation of mycotoxin accumulation in the Kenyan rice.
