Summary
Wheat streak mosaic virus (WSMV) is a persistent threat to wheat production, necessitating novel approaches for protection. We developed an artificial miRNA strategy against WSMV, incorporating five amiRNAs within one polycistronic amiRNA precursor. Using miRNA sequence and folding rules, we chose five amiRNAs targeting conserved regions of WSMV but avoiding off-targets in wheat. These replaced the natural miRNA in each of five arms of the polycistronic rice miR395, producing amiRNA precursor, FanGuard (FGmiR395), which was transformed into wheat behind a constitutive promoter. Splinted ligation detected all five amiRNAs being processed in transgenic leaves. Resistance was assessed over two generations. Three types of response were observed in T1 plants of different transgenic families: completely immune; initially resistant with resistance breaking down over time; and initially susceptible followed by plant recovery. Deep sequencing of small RNAs from inoculated leaves allowed the virus sequence to be assembled from an immune transgenic, susceptible transgenic, and susceptible non-transgenic plant; the amiRNA targets were fully conserved in all three isolates, indicating virus replication on some transgenics was not a result of mutational escape by the virus. For resistant families, the resistance segregated with the transgene. Analysis in the T2 generation confirmed the inheritance of immunity and gave further insights into the other phenotypes. Stable resistant lines developed no symptoms and no virus by ELISA; this resistance was classified as immunity when extracts failed to transmit from inoculated leaves to test plants. This study demonstrates the utility of a polycistronic amiRNA strategy in wheat against WSMV.

/pdf/resistance-to-wheat-streak-mosaic-virus-generated-by-2b5w23vwuf.pdf

Resistance to Wheat streak mosaic virus generated by expression of an artificial polycistronic microRNA in wheat

Insecticidal activity of essential oil from Cephalotaxus sinensis and its main components against various agricultural pests

The long-term viability of pastoralism has been a constant theme for discussions. The progress of knowledge on the sustainability of pastoralism under global environmental change has been notable in the last years. To better characterize this vulnerability, we have examined the existing scientific knowledge about the three dimensions of vulnerability, being exposure illustrated by the existing climate trends and non-climate transformations, sensitivity by the impacts of these on pastoral resources and pastoral land conversions, and adaptation by the adaptation strategies developed by the pastoral communities. A qualitative meta-analysis was conducted to explore patterns and trends across the literature. From this, six different pathways of vulnerability being followed by pastoral communities were identified: Encroachment, Re-greening, Customary, Polarization, Communal and No-alternative.

The results point that the livelihood options of pastoralists are generally becoming narrower. Four major forces are identified as exerting determinant influence on the co-production of the vulnerability of pastoralism: (i) the double exposure to climate and non-climate transformations, (ii) the persistence of unfavorable development policies, (iii) the great vitality of adaptation, and (iv) the multifaceted role of markets. We point that it is crucial to distinguish between the component of vulnerability inherent in any economic activity devoted to the use of natural resources, which is the usual business of pastoralism, and the component of vulnerability linked to external forces that disturb the usual working of the pastoral production strategies.

/pdf/what-drives-the-vulnerability-of-pastoralists-to-global-54jyb4rm38.pdf

What drives the vulnerability of pastoralists to global environmental change? A qualitative meta-analysis

Background:Sub-Saharan Africa is the last region to undergo a nutrition transition and can still avoid its adverse health outcomes.Objective:The article explores emerging responses to “bend the curve” in sub-Saharan Africa’s nutrition transition to steer public health outcomes onto a healthier trajectory.Methods:Early responses in 3 countries at different stages of food system transformation are examined: South Africa—advanced, Ghana—intermediate, and Uganda—early. By comparing these with international experience, actions are proposed to influence nutrition and public health trajectories as Africa’s food systems undergo rapid structural change.Results:Arising from rapid urbanization and diet change, major public health problems associated with overweight are taking place, particularly in South Africa and among adult women. However, public health responses are generally tepid in sub-Saharan Africa. Only in South Africa have policy makers instituted extensive actions to combat overweight and associated nonc...

https://journals.sagepub.com/doi/pdf/10.1177/0379572116637723

Emerging Early Actions to Bend the Curve in Sub-Saharan Africa's Nutrition Transition.

Knowledge on gene action and trait expression are important for effective breeding. The objective of this study was to determine the general combining ability (GCA), specific combining ability (SCA), maternal effects and heritability of drought tolerance, yield and yield components of candidate sweetpotato clones. Twelve genotypes selected for their high yield, dry matter content or drought tolerance were crossed using a full diallel mating design. Families were field evaluated at Masoro, Karama and Rubona Research Stations of Rwanda Agriculture Board. Success rate of crosses varied from 1.8 to 62.5% with a mean of 18.8%. Family by site interaction had significant effect (P<0.01) on storage root and vine yields, total biomass and dry matter content of storage roots. The family effects were significant (P< 0.01) for all parameters measured. Broad sense heritability estimates were 0.95, 0.84, 0.68, 0.47, 0.74, 0.75, 0.50 and 0.58 for canopy temperature (CT), canopy wilting (CW), root yield, skin colour, flesh colour, dry matter content, vine yield and total biomass, respectively. The GCA effects of parents and SCA effects of crosses were significant (P<0.01) for CT, CW, storage root, vine and biomass yields, and dry matter content of storage root. The ratio of GCA/SCA effects for CT, CW, yield of storage roots and dry matter content of storage roots were higher than 50%, suggesting the preponderance of additive over non-additive gene action in the expression of these traits. Maternal effects were significant (P<0.05) among families for CT, CW, flesh color and dry matter content, vine yield and total biomass. Across sites, the best five selected families with significant SCA effects for storage root yield were, Nsasagatebo x Otada 24, Otada 24 x Ukerewe, 4-160 x Nsasagatebo, K513261 x 2005-034 and Ukerewe x K513261 with 11.0, 9.7, 9.3, 9.2, 8.6 t/ha, respectively. The selected families are valuable genetic resources for sweetpotato breeding for drought tolerance, yield and yield components in Rwanda or similar environments.

/pdf/combining-ability-maternal-effects-and-heritability-of-2htdu18me4.pdf

Combining Ability, Maternal Effects, and Heritability of Drought Tolerance, Yield and Yield Components in Sweetpotato

Climatic variability has affected livelihoods of people in many ways chief among them being the dwindling water resources. Water is the most limiting factor in crop and livestock production in arid and semi-arid lands (ASALs) of sub-Saharan Africa. Rainfall which is the only source of water in these areas shows very high spatial and temporal variability. Effects of climatic change are already being experienced in these areas and global changes in climate are expected to further exacerbate the inherent vulnerability of communities living in such ecosystems. Communities have to deal with more uncertain weather, with extreme events occurring more frequently. For ecosystems in the rangelands, crop, forage and livestock production closely follow rainfall trends thus putting livelihoods of a number of households at risk. Farmers in these areas have adopted practices to cope with the climatic change and reduce their vulnerability. This study was carried out by administering questionnaires and the study area comprised of two administrative Districts namely Kibwezi and Kajiado, predominantly occupied by agropastoralists and semi-nomadic pastoralists respectively. The study area is located in the semi-arid southern rangelands of Kenya. The altitude of the area varies from 600m to 1,100m above sea level. The average annual rainfall, evaporation and temperatures are in the order of 600mm, 2,000mm and 23 0 C respectively. For over four decades, the study area has been experiencing increasing climatic anomalies. In the agro-pastoral areas, mixed farming of crops such as maize, green grams and pigeon peas is the main source of livelihood, whereas livestock production is the main activity in the pastoral areas. Most (98%) of the respondents mentioned increased dry conditions occasioned by recurrent droughts as the main unusual climatic events experienced over the years and the extended dry conditions are experienced almost every year. The extreme weather conditions have affected the agro-pastoralists more than the pastoralists. The impacts of the climatic change are also reflected in increased crop failures; change of type of crops grown and livestock species kept; low crop, forage and livestock productivity; poor health of crops and livestock; reduction in land under cultivation; change of planting time; reduced daily food consumption; increased livestock and human diseases; and change in livestock management plans. In response to climate variability, households had developed both short and long term coping/adaptive mechanisms which includes planting of drought tolerant and early maturing crops, run-off harvesting, water harvesting using micro-catchments, early or dry planting, increased migration of men to urban centers to seek wage employment, de-stocking of herds, change of herd structure. The study shows that the main response to water scarcity for crops is run-off harvesting and drilling of boreholes.

Livelihoods under climate variability and change: an analysis of the adaptive capacity of rural poor to water scarcity in Kenya's drylands.

Determinants of fast-food consumption in Kampala, Uganda.

/pdf/diallel-analysis-of-root-dry-matter-content-in-sweetpotato-54qnt73598.pdf

Diallel analysis of root dry matter content in sweetpotato

Morphological and genetic characterization of mango varieties in Mozambique.

Research Application Summary Insect pests attacking stored food grains cause substantial losses that undermine food security in sub-Sahara Africa. Subsistence farmers predominantly use traditional plant-based products to protect their grains in storage. In an attempt to seek alternatives to synthetic fumigants, laboratory screening of essential oil constituents were conducted to evaluate their fumigant toxicity against five stored-product insects, Sitophilus oryzae L., Rhyzopertha dominica F., Tribolium castaneum (Herbst), Oryzaephilus surinamensis L. and Callosobruchus chinensis F. Five essential oil constituents, ahumulene, caryophyllene oxide, myrcene, R(+)-apinene and R(+)-âpinene were each evaluated at four (0, 1, 5 and 10 μl/L air) rates in space fumigation chambers with four replicates per concentration. Results revealed a strong dose-, insect speciesand time-dependent fumigant toxicity in which caryophyllene oxide, myrcene, ahumulene, R(+)-apinene and R(+)-âpinene caused 18-100%, 49-100, 55.4-100, 47.3-100 and 32.5100% adult mortalities of all test insects, except the most tolerant species, T. castaneum, at 10 μl/L air 168 h after treatment. Against all the test insects, except T. castaneum, Probit regression analysis produced end-point LC50 values of 0.038.5, 0.03-7.0, 0.01-4.82, 0.01-8.20 and 0.03-6.5 μl/L air for the five essential constituents, respectively. The observed fumigant potency levels could possibly be explained by variations in compound structure-insecticidal activity relationships that influenced their degree of penetration into the insect cuticle and neurotoxicity. These findings provide the scientific basis for using essential oils as fumigants against stored-product insect pests and hence, potential alternatives to synthetic fumigants in both subsistence and commercial agriculture. Further studies Fumigant toxicity of five essential oil constituents against major stored-product insect pests of food grains Ogendo, J.O.1, Deng, A.L.5, Kostyukovsky, M.2, Ravid, U.3,Matasyoh, J.C.4, Omolo, E.O.1, Kariuki, S.T.5, Bett, P.K.5, Kamau, E. A.W. 1 & Shaaya2 1Department of Crops, Horticulture and Soils, Egerton University, P.O. Box 536 Egerton 20115, Kenya 2Department of Food Science, ARO, The Volcani Center, Bet Dagan 50250, Israel 3Department of Aromatic, Medicinal and Spice Crops, ARO, Newe Ya’ar Research Center, Ramat Yishay 30095, Israel 4Department of Chemistry, Egerton University, P.O. Box 536 Egerton 20115, Kenya 5Department of Biological Sciences, Egerton University, P.O. Box 536 Egerton 20115, Kenya Corresponding author: ogendojoshua@yahoo.co.uk, jogendo@egerton.ac.ke

/pdf/fumigant-toxicity-of-five-essential-oil-constituents-against-33p1nqwzlq.pdf

Fumigant toxicity of five essential oil constituents against major stored-product insect pests of food grains

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