Heterosis for yield and its components in sorghum (Sorghum bicolor L. Moench) hybrids in dry lands and sub-humid environments of East Africa

A study was conducted in 2011 and 2012 growing seasons to determine levels of heterosis and identify parents for use in sorghum hybrid production in East Africa. A total of 36 pairs of male sterile lines and 42 restorers were obtained from ICRISAT-Nairobi and used for generating 121 experimental hybrids in a line × tester mating design. The hybrids were then evaluated at Kiboko, Ukiriguru and Miwaleni locations in an alpha lattice design with three replications. Each genotype was grown in a 4 m long row at spacing of 60 cm ×50 cm. Phenotypic data were collected as per IPGRI, (1993) descriptors for sorghum on five randomly selected plants. There were significant differences among locations, crosses and male parents for all the characters studied. Female lines were highly significant for all traits except days to 50% flowering (DAF). Desired heterobeltiosis for DAF varied from -5.23 to -14% indicating of early maturing material that can escape terminal drought in rainfed agriculture, characteristic of East African cultivation system. Lowest (desired) heterobeltiosis for plant height was -53.61% with crosses ICSA15×Tegemeo and ATX623×KARI-MTAMA1most promising for this trait. Grain yield showed average heterosis and heterobeltiosis of up to 81.90% and 77.18% respectively both expressed in ICSA11×S35. The parents KARI MTAMA1, IESV91104DL, S35, BTX623, ICSB12 and ICSB11 produced hybrids that yielded high with medium height and maturity therefore could be included to develop hybrid sorghum for East Africa region

Combining ability of some sorghum lines for dry lands and sub-humid environments of East Africa

Sorghum (Sorghum bicolor L. Moench) is a major food crop grown in dry lands and sub-humid areas of East Africa. A study was conducted between 2010 to 2012 in dry lands (Miwaleni, Kiboko) and sub-humid (Ukiriguru) environments to identify parents for hybrid production. It involved 121 lines from ICRISAT and 121 hybrids developed from 36 male sterile lines and 42 restorer lines in a line × tester crossing. Experiments were planted in an alpha lattice design with three replications. Analysis revealed significant (P < 0.05) differences between parents and between crosses for yield and yield components, indicative of potentiality for exploitation. Line IESV23010 expressed best (-6.5) general combing ability (GCA) for days to 50% flowering (DAF). Highest general combiner for height was -55.4 expressed in ICSR24007 and for yield was 382.8 expressed in IESV92156DL. The crosses SDSA4×ICSR43 and SDSA4×ICSR59059 exhibited high and significant specific combining ability (SCA) for DAF. Lines IESB2 and ICSB44 were suited to sub-humid, whereas BTX623, ICSB15 and ICSB6 to dry lands environments. Testers IESV91104DL, IESV91131DL, ICSR93034 were well suited to dry lands whereas KARI-MTAMA1 and IESV23019 to sub-humid environments. The parents identified could be used to produce hybrids and varieties for the dry lands and sub-humid environments

Identification of SNP and SSR Markers in Finger Millet Using Next Generation Sequencing Technologies

Finger millet is an important cereal crop in eastern Africa and southern India with excellent grain storage quality and unique ability to thrive in extreme environmental conditions. Since negligible attention has been paid to improving this crop to date, the current study used Next Generation Sequencing (NGS) technologies to develop both Simple Sequence Repeat (SSR) and Single Nucleotide Polymorphism (SNP) markers. Genomic DNA from cultivated finger millet genotypes KNE755 and KNE796 was sequenced using both Roche 454 and Illumina technologies. Non-organelle sequencing reads were assembled into 207 Mbp representing approximately 13% of the finger millet genome. We identified 10,327 SSRs and 23,285 non-homeologous SNPs and tested 101 of each for polymorphism across a diverse set of wild and cultivated finger millet germplasm. For the 49 polymorphic SSRs, the mean polymorphism information content (PIC) was 0.42, ranging from 0.16 to 0.77. We also validated 92 SNP markers, 80 of which were polymorphic with a mean PIC of 0.29 across 30 wild and 59 cultivated accessions. Seventy-six of the 80 SNPs were polymorphic across 30 wild germplasm with a mean PIC of 0.30 while only 22 of the SNP markers showed polymorphism among the 59 cultivated accessions with an average PIC value of 0.15. Genetic diversity analysis using the polymorphic SNP markers revealed two major clusters; one of wild and another of cultivated accessions. Detailed STRUCTURE analysis confirmed this grouping pattern and further revealed 2 sub-populations within wild E. coracana subsp. africana. Both STRUCTURE and genetic diversity analysis assisted with the correct identification of the new germplasm collections. These polymorphic SSR and SNP markers are a significant addition to the existing 82 published SSRs, especially with regard to the previously reported low polymorphism levels in finger millet. Our results also reveal an unexploited finger millet genetic resource that can be included in the regional breeding programs in order to efficiently optimize productivity

Identification of SNP and SSR Markers in Finger Millet Using Next Generation Sequencing Technologies

Finger millet is an important cereal crop in eastern Africa and southern India with excellent grain storage quality and unique ability to thrive in extreme environmental conditions. Since negligible attention has been paid to improving this crop to date, the current study used Next Generation Sequencing (NGS) technologies to develop both Simple Sequence Repeat (SSR) and Single Nucleotide Polymorphism (SNP) markers. Genomic DNA from cultivated finger millet genotypes KNE755 and KNE796 was sequenced using both Roche 454 and Illumina technologies. Non-organelle sequencing reads were assembled into 207 Mbp representing approximately 13% of the finger millet genome. We identified 10,327 SSRs and 23,285 non-homeologous SNPs and tested 101 of each for polymorphism across a diverse set of wild and cultivated finger millet germplasm. For the 49 polymorphic SSRs, the mean polymorphism information content (PIC) was 0.42, ranging from 0.16 to 0.77. We also validated 92 SNP markers, 80 of which were polymorphic with a mean PIC of 0.29 across 30 wild and 59 cultivated accessions. Seventy-six of the 80 SNPs were polymorphic across 30 wild germplasm with a mean PIC of 0.30 while only 22 of the SNP markers showed polymorphism among the 59 cultivated accessions with an average PIC value of 0.15. Genetic diversity analysis using the polymorphic SNP markers revealed two major clusters; one of wild and another of cultivated accessions. Detailed STRUCTURE analysis confirmed this grouping pattern and further revealed 2 sub-populations within wild E. coracana subsp. africana. Both STRUCTURE and genetic diversity analysis assisted with the correct identification of the new germplasm collections. These polymorphic SSR and SNP markers are a significant addition to the existing 82 published SSRs, especially with regard to the previously reported low polymorphism levels in finger millet. Our results also reveal an unexploited finger millet genetic resource that can be included in the regional breeding programs in order to efficiently optimize productivity

Characterisation of botanical starches as potential substitutes of agar in tissue culture media

Seven botanical starches; cassava, sweet potato, Irish potato, maize, rice, wheat and sorghum were characterized to determine physicochemical properties influencing gel formation for preparation of tissue culture media. Total starch, protein, fat, amylose content, swelling power and pH were determined using acid hydrolysis, enzymic and spectrophotmetric methods. Each type of starch was tested for ability to support in vitro plant growth and 0.8% agar (w/v) was used as standard. Nodal explants cultures were initiated in Murashige and Skoog medium supplemented with 3% sucrose and 0.5 mg/l benzylaminopurine (BAP). After 21 days, number of leaves and nodes, plant height and fresh weight were determined for each  treatment. Significant (0.05) differences were observed between starch types in total starch, protein content and fats. Cassava had the highest starch content (81.5%) and irish potato had the lowest (29.3%). Highest protein content (12%) was observed in maize starch and the lowest (3.4%) in cassava. Fat content was highest (6.2%) in wheat and lowest in cassava (0.2%). Starch extract from rice had the highest amylose content (31.12%) while the cassava starch extracts had the lowest (20.75%). The starch extracted from wheat had the highest swelling power (105.1%) while irish potato starch had the lowest (52.1%). Sorghum starch had the lowest pH of 4.57 while the highest (6.92) was recorded in Irish potato starch. The growth of shoots in vitro on agar gelled media outperformed those of starch gelled media except for the number of leaves per shoot which cassava starch media recorded significantly the highest response (P = 0.05). Of all the starch gelled media, the best growth response was observed with cassava. Good performance was observed in starches with high starch content, low amylose content and high swelling powers. Key words: Starch, agar, gelling agent, in vitro plant growth

Implantation de filtres digitaux récursifs à deux dimensions

Les effets de la précision limitée sont considérés pour les filtres digitaux récursifs à deux dimensions. Des erreurs sont introduites dans la quantification de l'entrée, dans les coefficients et dans l'évaluation des multiplications des implantations de filtres. Des modèles de filtres à longueur de registres fini sont développés et différentes formes de réalisation sont montrées. Une approche statistique est adoptée, ce qui permet de calculer la distribution d'erreurs à la sortie de filtres. L'arrondissement et la coupure sont comparés comme méthodes de quantification. Différentes formes d'arithmétique à point fixe sont considérées et quelques examples sont donnés

Characterisation of botanical starches as potential substitutes of agar in tissue culture media

African Journal of Biotechnology, 2015; 14 (8): 702-713Seven botanical starches; cassava, sweet potato, Irish potato, maize, rice, wheat and sorghum were characterized to determine physicochemical properties influencing gel formation for preparation of tissue culture media. Total starch, protein, fat, amylose content, swelling power and pH were determined using acid hydrolysis, enzymic and spectrophotmetric methods. Each type of starch was tested for ability to support in vitro plant growth and 0.8% agar (w/v) was used as standard. Nodal explants cultures were initiated in Murashige and Skoog medium supplemented with 3% sucrose and 0.5 mg/l benzylaminopurine (BAP). After 21 days, number of leaves and nodes, plant height and fresh weight were determined for each treatment. Significant (0.05) differences were observed between starch types in total starch, protein content and fats. Cassava had the highest starch content (81.5%) and irish potato had the lowest (29.3%). Highest protein content (12%) was observed in maize starch and the lowest (3.4%) in cassava. Fat content was highest (6.2%) in wheat and lowest in cassava (0.2%). Starch extract from rice had the highest amylose content (31.12%) while the cassava starch extracts had the lowest (20.75%). The starch extracted from wheat had the highest swelling power (105.1%) while irish potato starch had the lowest (52.1%). Sorghum starch had the lowest pH of 4.57 while the highest (6.92) was recorded in Irish potato starch. The growth of shoots in vitro on agar gelled media outperformed those of starch gelled media except for the number of leaves per shoot which cassava starch media recorded significantly the highest response (P = 0.05). Of all the starch gelled media, the best growth response was observed with cassava. Good performance was observed in starches with high starch content, low amylose content and high swelling powers

Characterisation of botanical starches as potential substitutes of agar in tissue culture media

African Journal of Biotechnology, 2015; 14 (8): 702-713Seven botanical starches; cassava, sweet potato, Irish potato, maize, rice, wheat and sorghum were characterized to determine physicochemical properties influencing gel formation for preparation of tissue culture media. Total starch, protein, fat, amylose content, swelling power and pH were determined using acid hydrolysis, enzymic and spectrophotmetric methods. Each type of starch was tested for ability to support in vitro plant growth and 0.8% agar (w/v) was used as standard. Nodal explants cultures were initiated in Murashige and Skoog medium supplemented with 3% sucrose and 0.5 mg/l benzylaminopurine (BAP). After 21 days, number of leaves and nodes, plant height and fresh weight were determined for each treatment. Significant (0.05) differences were observed between starch types in total starch, protein content and fats. Cassava had the highest starch content (81.5%) and irish potato had the lowest (29.3%). Highest protein content (12%) was observed in maize starch and the lowest (3.4%) in cassava. Fat content was highest (6.2%) in wheat and lowest in cassava (0.2%). Starch extract from rice had the highest amylose content (31.12%) while the cassava starch extracts had the lowest (20.75%). The starch extracted from wheat had the highest swelling power (105.1%) while irish potato starch had the lowest (52.1%). Sorghum starch had the lowest pH of 4.57 while the highest (6.92) was recorded in Irish potato starch. The growth of shoots in vitro on agar gelled media outperformed those of starch gelled media except for the number of leaves per shoot which cassava starch media recorded significantly the highest response (P = 0.05). Of all the starch gelled media, the best growth response was observed with cassava. Good performance was observed in starches with high starch content, low amylose content and high swelling powers

Identification of Candida strains isolated from Tanzanian pregnant women with vaginal candidiasis

Objective: To identify Candida strains isolated from Tanzanian women (13 to 45 years) with vaginal candidiasis. Design: A cross-sectional study. Setting: Antenatal clinic in llala district hospital in Dar es Salaam, Tanzania from March 1998 to December 2000. Results: The identities of the 272 isolates tested with API Candida were: Candida albicans 180(66.2%), Candida tropicalis 13(4.7%), Candida glabrata 20(7.35%), Candida famata 6(2.2%), Candida parapsilosis 6 (2.2%) and Candida lusitaniae one (0.37%). API Candida could not speciate 43 (15.8%) isolates of these; two (0.7%) fell between C. albicans and C. tropicalis, 17(6.25%) C. Iusitaniael, C. guilliermondii/C. famata, 14(5.15%) C. krusei, C. inconspicua, and C. norvegensis and nine (3.3%) either C. parapsilosis, C. krusei, C. incospicua or Geotrichum spp. Four (1.5%) isolates had an assimilation pattern of Trichosporo spp, but were all germ tube positive and had morphological features on cornemeal agar that were consistent with C. albicans. API 20C AUX was used for testing 29 isolates and results showed: 11/29 (37.9%) C. albicans, 1/29 (3.4%) C. tropicalis, 4/29 (13.8%) C. glabrata, 1/29 (3.4%) C. parapsilosis, 1/29 (3.4%) C. famata, 1/29 (3.4%) C. lusitaniae, 1/29 (3.4%) C. colliculosa/C. magnoliae, 5/29(17.2%) C. albicans/ C. tropicals 2/29 (6.8%) C. norvegensis/C. parapsilosis, and 2/29(6.8%) C. kruseil/C. inconspicua. Results of 20 isolates identified by Randomly Amplified Polymorphic DNA (RAPID) technique showed a 95% agreement with API Candida and a 100% agreement with API 20C AUX. Conclusion: Although most (66.3%) of the species isolated from Dar es Salaam women with vaginal candidiasis were C. albicans, a considerable percentage (33.7%) were nonalbicans, mainly C. glabrata, C. krusei and C. tropicalis. The high prevalence of non-albicans Candida spp observed in this population may have therapeutic implications.East African Medical Journal Vol. 82(5) 2005: 226-23