No abstract

No abstract

The goal of this study was to develop an efficient regeneration protocol to be used for genetic transformation of sesame. Published regeneration methods using benzyladenine (BA) and 1-naphthalene acetic acid (NAA) were unsuccessful for the cultivars used herein. Experiments were carried out using cotyledon and hypocotyl explants from the cultivar Mtwara-2. Later the optimised culture conditions were used to investigate the regeneration response of different genotypes. There was significant interaction between hormone treatments and macronutrients for shoot and root regeneration. Results also showed that shoot regeneration was significantly influenced by explant type. Shoots were only obtained from cotyledons whereas both cotyledons and hypocotyls could produce roots. Modified Murashige and Skoog (MS) medium with N6 macronutrients resulted in twice the shoot regeneration frequency obtained with ½MS macronutrients in the presence of thidiazuron (TDZ). The shoot regeneration frequency was significantly reduced when BA was used in place of TDZ. On shoot regeneration medium containing BA and NAA, only roots were formed. Replacing NAA with indole-3-acetic acid (IAA) greatly improved the regeneration of shoots. The optimum growth regulator combination for shoot regeneration was 20 lM TDZ together with 2.5 lM IAA, which gave a frequency of 63% and 4.4 shoots per regenerating explant for the best cultivar Ex-El. Genotypic differences were significant both for the number of explants regenerating shoots and the number of shoots produced per regenerating explant.

Background: Maize is the major food staple in East and Southern Africa, where food-processing industries are emerging fast. New low-cost extrusion cookers allow small enterprises to enter the market for processed cereals, including instant, fortified, and flavored products. Objective: Assess consumers’ interest and preferences for the new products. Methods: Consumers (n = 220) in Eldoret, Kenya, were invited to evaluate 4 new cereal products: (1) sifted maize flour mixed with sorghum, (2) instant sifted mixed flour, (3) instant whole flour, and (4) instant whole flour fortified with natural ingredients and to compare them to conventional sifted maize flour, using 2 preparations: stiff porridge ( ugali) and soft porridge ( uji). These were followed by economic experiments to estimate consumers’ willingness to pay (WTP) for the new products and traits. Results: For ugali, consumers preferred conventional sifted maize flour, while for uji, they appreciated the new products, especially sifted mixed flour (with sorghum) and instant whole mixed flour. Fortification with food-to-food sources was not appreciated, especially for ugali. Comparing WTP for the traits with their production cost showed that mixed, whole, and instant flours were economical, but not fortification. Maize/sorghum mixtures realized a benefit of 24% over conventional maize flour, whole meal 11%, and instant mixtures 5%. Conclusions: There is a potential market for improved cereal products in Kenya, but more for uji than for ugali, especially with instant, mixed, and whole flour. Acceptable and affordable products, fortified with other foods that are locally available, however, still need to be developed, especially for ugali.

Aluminum (Al) toxicity on acid soils adversely affects maize yields, which can be overcome by combining soil amendments with genetic tolerance. In maize, ZmMATE1 confers Al tolerance via Al-activated citrate release, whereby citrate forms non-toxic complexes with Al3+ in the rhizosphere. Here, we investigated Al tolerance mechanisms in maize germplasm originated from Kenya based on quantitative trait loci (QTL) mapping. Five QTLs and four epistatic interactions explained ~51% of the phenotypic variation for Al tolerance. The lack of Al tolerance QTL on chromosome 6 and the much lower expression of ZmMATE1 in both Kenyan lines than in Cateto Al237, which donates the superior allele of ZmMATE1, strongly indicate that this gene does not play a significant role in Al tolerance in neither parent. In turn, maize homologs to genes previously implicated in Al tolerance in other species, ZmNrat1, ZmMATE3, ZmWRKY and ZmART1, co-localized with Al tolerance QTL and were more highly expressed in the parent that donate favorable QTL alleles. However, these candidate genes will require further studies for functional validation on maize Al tolerance. The existence of Al tolerance mechanisms independent from ZmMATE1 suggests it is possible to develop highly Al tolerant cultivars by pyramiding complementary Al tolerance genes in maize.