Development of micropropagation system for yam (Dioscorea spp.) using somatic embryogenesis

Inadequate availability of disease-free planting materials remains a major constraint to yam production. The tissue culture technique has been used to regenerate disease-free plantlets from pre-formed, heattreated meristems followed by micropropagation. This procedure, however, has a low multiplication ratio with an average of 1: 4 every eight weeks. Embryo production from somatic cells (somatic embryogenesis, SE) is a system in which each somatic cell can regenerate a complete plantlet. However, previous reports show low SE induction frequencies and significant variations in success rates among different genotypes while hardly any report exist for improved varieties that farmers desire, especially in Nigeria. Studies were carried out to evaluate the effects of different plant growth regulators (PGRs) on induction of somatic embryogenesis of the following genotypes: one improved Dioscorea alata (TDa 291) and three improved (TDr 95/19177, TDr 89/2665, TDr 95/18544) and one landrace (Obioturugo) of Dioscorea rotundata. Leaf, stem, and axillary bud explants were cultured in MS basal medium containing fifteen treatment combinations of 2,4-Dichlorophenoxyacetic acid (2,4-D), Naphthaleneacetic acid (NAA), Benzylaminopurine (BAP), Picloram, and Uniconazole-P (UP). The genotype TDr 95/19177 was tested for SE in Temorary Immersion Bioreactor System (TIBS). The incidence of induction of callus formation and plantlet regeneration from the three explants were recorded. Embryogenic callus induction was highest (87%) from axillary buds cultured on modified MS + 2 mg/l of 2,4-D + 1 mg/l of NAA while 1 mg/l of BAP + 9. 9 mg/l of UP had the highest percentage plantlet regeneration of 50% in TDr 95/18544 and an average of 37% across genotypes at a mean of 5 plantlets per explant. The genotype TDr 95/19177 was successfully regenerated via indirect somatic embryogenesis in the SETIS Type Temporary Immersion Bioreactor System

Key for a profitable and sustainable seed yam business enterprise: business plan and market development with record keeping for seed yam farmers

Bill & Melinda Gates FoundationPeer Revie

Seed yam production from whole tubers versus minisetts

Open Access Article; Published online: 22 June 2020Yam (Dioscorea rotundata Poir.) is a major staple and cash crop for millions of households in West Africa, where about 93% of the world crop is produced. The tuber serves as food and seed. Depending on the size, seed tubers are often cut into setts, minisetts, or planted whole. An experiment was conducted to investigate the effects of using whole tubers versus minisetts to produce seed yams. Six treatments constituted combinations of whole tubers and minisetts, and three tuber-size classes, viz., 30–59 g, 60–89 g, and 90–120 g (averaged and referred to as 45 g, 75 g, and 105 g, respectively). The experiment was conducted as a randomized complete block design with three replications. Results showed that plants from whole tubers emerged from the soil faster and yielded 48% more than those from minisetts. The mean yield of 105 g minisetts (18.3 t/ha) was statistically similar to that of 45 g whole seed (17.9 t/ha). Using 45 g whole seed would save about 2 t/ha of the harvested crop for use as food instead of seed. So, planting small whole tubers is more profitable than minisetts and is recommended to yam growers

Genetic by environment interaction on fresh root yield, dry matter content and total carotene concentration of yellow-fleshed cassava genotypes in five major cassava growing agroecological zones in Nigeria

Eighteen yellow-fleshed cassava genotypes and two released white-fleshed clones (check) were evaluated in five locations representing the major cassava growing agroecological zones of Nigeria to access their performance for fresh root yield, dry matter content, total carotene content and genotypes by environment interaction effects. The aim of the study was to identify stable cassava genotypes that combine high root yield, and high dry matter with high beta carotene content in storage root. The study was conducted in two cropping seasons (2008/2009 and 2009/2010) at Ikenne (humid forest), Ibadan (forest-savanna transition), Ubiaja (sub-humid forest), Mokwa (sub-humid southern-Guinea savanna) and Zaria (moist northern-Guinea savanna). At all locations, the trials were conducted in a randomised complete block design (RCBD) with four replications. The combined analysis of variance showed that fresh root yield (t ha-1), dry matter content (%) and total carotene content (μg g-1 fresh weight) was significantly affected (P < 0.001) by Genotype (G), Environment E, and G × E interaction. For fresh root yield, the best genotype was IITA TMS I050024 followed by IITA TMS I050998 and IITA TMS I050286. For dry matter content of the storage roots, the genotype IITA TMS 1051570 had the highest score followed by IITA TMS 1051740 and IITA IMS I050998. For total carotene content, the best genotypes across the 10 environments in decreasing order of carotene content were IITA TMS I051601, IITA TMS I050311, IITA TMS I050998 and IITA TMS I050099. When combining fresh root yield and dry matter content (dry yield), the genotypes IITA TMS I050998 and IITA TMS I051740 ranked highest. The Environment effect accounted for most of the variation of the total sum of squares (SS) for fresh root yield (55.0%), dry matter content (42.3%) and dry yield (57.9%). The genotype accounted for most of the SS for total carotene content (67.9%)

Overexpression of biotin synthase and biotin ligase is required for efficient generation of sulfur-35 labeled biotin in E. coli

<p>Abstract</p> <p>Background</p> <p>Biotin is an essential enzyme cofactor that acts as a CO₂carrier in carboxylation and decarboxylation reactions. The <it>E. coli </it>genome encodes a biosynthetic pathway that produces biotin from pimeloyl-CoA in four enzymatic steps. The final step, insertion of sulfur into desthiobiotin to form biotin, is catalyzed by the biotin synthase, BioB. A dedicated biotin ligase (BirA) catalyzes the covalent attachment of biotin to biotin-dependent enzymes. Isotopic labeling has been a valuable tool for probing the details of the biosynthetic process and assaying the activity of biotin-dependent enzymes, however there is currently no established method for ³⁵S labeling of biotin.</p> <p>Results</p> <p>In this study, we produced [³⁵S]-biotin from Na³⁵SO₄and desthiobiotin with a specific activity of 30.7 Ci/mmol, two orders of magnitude higher than previously published methods. The biotinylation domain (<it>Pf</it>BCCP-79) from the <it>Plasmodium falciparum </it>acetyl-CoA carboxylase (ACC) was expressed in <it>E. coli </it>as a biotinylation substrate. We found that overexpression of the <it>E. coli </it>biotin synthase, BioB, and biotin ligase, BirA, increased <it>Pf</it>BCCP-79 biotinylation 160-fold over basal levels. Biotinylated <it>Pf</it>BCCP-79 was purified by affinity chromatography, and free biotin was liberated using acid hydrolysis. We verified that we had produced radiolabeled biologically active [<it>D</it>]-biotin that specifically labels biotinylated proteins through reuptake in <it>E. coli</it>.</p> <p>Conclusions</p> <p>The strategy described in our report provides a simple and effective method for the production of [³⁵S]-biotin in <it>E. coli </it>based on affinity chromatography.</p