Optimisation of in vitro techniques for cassava brown streak virus elimination from infected cassava clones

Cassava brown streak disease (CBSD), caused by Cassava brown streak virus (CBSV), is an economically important disease of cassava (Manihot esculenta Crantz) in East Africa. The objective of this study was tooptimise in vitro techniques for CBSV elimination from infected Ugandan cassava cultivars. Using semi-solid halfstrength Murashige and Skoog (MS) basal medium, hormone concentration and heat treatment regimes wereoptimised for micropropagation of farmer’s preferred cassava cultivars and CBSV elimination. Single nodes from young cassava stems were cultured for four weeks on ½MS medium supplemented with 6-benzyl amino purine(BAP) and 2,4-dichlorophenoxy acetic acid (2,4-D). The BAP and 2,4-D concentration (mg l-1) combinations used were 0.0 and 0.0, 0.5 and 0.1, 1.0 and 0.2, 1.5 and 0.3, and 2.0 and 0.4, respectively. The optimum medium was used for in vitro thermotherapy using four temperature regimes, namely 30-34, 34-38, 36-40 and 38-42 oC for 8 hoursdarkness and 16 hours light, respectively, for four weeks. The best plantlet growth in terms of height was observed on MS medium supplemented with 0.5 mg l-1 BAP and 0.1 mg l-1 2,4-D. Highest CBSV elimination efficiency of 40%, with 49% plantlet survival was observed at 36 oC for 8 hours darkness and 40 oC for 16 hours light. These results indicate that in vitro techniques can greatly enhance CBSV elimination and, thus, provide a means of CBSD management through dissemination and conservation of popular but CBSD susceptible cultivars

Do surveys with paper and electronic devices differ in quality and cost? Experience from the Rufiji Health and demographic surveillance system in Tanzania

Data entry at the point of collection using mobile electronic devices may make data-handling processes more efficient and cost-effective, but there is little literature to document and quantify gains, especially for longitudinal surveillance systems.; To examine the potential of mobile electronic devices compared with paper-based tools in health data collection.; Using data from 961 households from the Rufiji Household and Demographic Survey in Tanzania, the quality and costs of data collected on paper forms and electronic devices were compared. We also documented, using qualitative approaches, field workers, whom we called 'enumerators', and households' members on the use of both methods. Existing administrative records were combined with logistics expenditure measured directly from comparison households to approximate annual costs per 1,000 households surveyed.; Errors were detected in 17% (166) of households for the paper records and 2% (15) for the electronic records (p < 0.001). There were differences in the types of errors (p = 0.03). Of the errors occurring, a higher proportion were due to accuracy in paper surveys (79%, 95% CI: 72%, 86%) compared with electronic surveys (58%, 95% CI: 29%, 87%). Errors in electronic surveys were more likely to be related to completeness (32%, 95% CI 12%, 56%) than in paper surveys (11%, 95% CI: 7%, 17%).The median duration of the interviews ('enumeration'), per household was 9.4 minutes (90% central range 6.4, 12.2) for paper and 8.3 (6.1, 12.0) for electronic surveys (p = 0.001). Surveys using electronic tools, compared with paper-based tools, were less costly by 28% for recurrent and 19% for total costs. Although there were technical problems with electronic devices, there was good acceptance of both methods by enumerators and members of the community.; Our findings support the use of mobile electronic devices for large-scale longitudinal surveys in resource-limited settings

Influence of spectral properties on cassava leaf development and metabolism

Cassava’s importance as a food security crop in Sub Saharan Africa will be enhanced by its special traits such as tolerance to drought and high yields under hydrothermal stress. Some of the special traits which include the light reflective and absorptive properties of the leaves that depend on the surface characteristics of the leaves, are variety dependent and may influence the plants’ reaction to light; hence, its photosynthetic capacity. We investigated the differences in the leaf spectral properties in different cassava varieties and related them to leaf biochemical properties using 20 cassava varieties established in a randomized complete block design in Kasese, western Uganda. Time dependent changes in leaf spectral characteristics were studied using Digimizer software and related to changes in sugar and pigment properties. Changes in the amount of reflected light were observed for the three main wavelengths used by plants (blue, green and red) with the blue being the most preferred. Total soluble free sugars exhibited a diurnal pattern from lower values (0.07 mg/g) after the dark period to higher values (0.313 mg/g) as the day progressed and was different from those of translocatable sugars such as sucrose. Chlorophyll a exhibited a curved pattern in all varieties increasing with increase in light intensity from 09:00 h (0.18 ug/g), peaking at 15:00 h (0.22 ug/g) and dropping down in concentration by 18:00 h (0.16 ug/g). Significant differences were observed in cassava varieties for the concentration of chlorophylls and carotenes. The results were obtained at a time of optimal growth conditions (four months after planting) and were used to classify these varieties into three broad groups showing that studies on spectral properties of leaves can still give a lot of insights in selection for stress tolerance under less optimal stress. The significant changes observed in the phenotype especially the foliar portion of the plant with the stay green and early recovering mechanisms of tolerance identified also tarried well with observed spectral differences. The results show that studies on plant spectral properties can be important in making inferences on the plants physiological and growth status.Keywords: Spectral properties, tolerance mechanisms, physiology, reflectance

Optimisation of in vitro techniques for Cassava brown streak virus elimination from infected cassava clones

Cassava brown streak disease (CBSD), caused by Cassava brown streak virus (CBSV), is an economically important disease of cassava ( Manihot esculenta Crantz) in East Africa. The objective of this study was to optimise in vitro techniques for CBSV elimination from infected Ugandan cassava cultivars. Using semi-solid half-strength Murashige and Skoog (MS) basal medium, hormone concentration and heat treatment regimes were optimised for micropropagation of farmer's preferred cassava cultivars and CBSV elimination. Single nodes from young cassava stems were cultured for four weeks on 1/2MS medium supplemented with 6-benzyl amino purine (BAP) and 2,4-dichlorophenoxy acetic acid (2,4-D). The BAP and 2,4-D concentration (mg 1-1) combinations used were 0.0 and 0.0, 0.5 and 0.1, 1.0 and 0.2, 1.5 and 0.3, and 2.0 and 0.4, respectively. The optimum medium was used for in vitro thermotherapy using four temperature regimes, namely 30-34, 34-38, 36-40 and 38-42 \ub0C for 8 hours darkness and 16 hours light, respectively, for four weeks. The best plantlet growth in terms of height was observed on MS medium supplemented with 0.5 mg 1-1 BAP and 0.1 mg 1-1 2,4-D. Highest CBSV elimination efficiency of 40%, with 49% plantlet survival was observed at 36 \ub1C for 8 hours darkness and 40 oC for 16 hours light. These results indicate that in vitro techniques can greatly enhance CBSV elimination and, thus, provide a means of CBSD management through dissemination and conservation of popular but CBSD susceptible cultivars.La maladie de la striure brune du manioc (CBSD) caus\ue9e par le virus de la striure brune (CBSV), est une maladie \ue9conomiquement importante du manioc ( Manihot esculenta Crantz) en Afrique de l'Est. L'objectif de cette \ue9tude \ue9tait d'optimiser les techniques in vitro pour l'\ue9limination du CBSV des cultivars ougandais infect\ue9s. En utilisant le m\ue9dium basal semi-solid half strength Murashige and Skoog, la concentration d'hormone et les regimes de traitement de chaleur \ue9taient optimis\ue9s pour la micropropagation des cultivars de manioc pr\ue9f\ue9r\ue9s par les fermiers et l'\ue9limination du CBSV. Les nodes simples des jeunes tiges de manioc \ue9taient cultiv\ue9s pendant quatre semaines sur le m\ue9dium 1/2 MS suppl\ue9ment\ue9s avec 6-benzyl amino purine (BAP) et 2,4-dichlorophenoxy acetic acid. Les combinaisons de concentrations (mg 1-1) de BAP et de 2.4-D utilis\ue9es \ue9taient 0.0 et 0.0, 0.5 et 0.1, 1.0 et 0.2, 1.5 et 0.3, et 2.0 et 0.4, respectivement. Le m\ue9dium optimum \ue9tait utilis\ue9 pour la thermoth\ue9rapie utilisant quatre regimes de temp\ue9rature dont 30-34, 34-38, 36-40 et 38-42 \ub0C pendant 8 heures en obscurit\ue9 et 16 heures sous lumi\ue8re, respectivement pendant quatre semaines. La meilleure croissance en hauteur des plantules \ue9tait observ\ue9e sur le m\ue9dium MS suppl\ue9ment\ue9 avec 0.5 mg 1-1 BAP et 0.1 mg 1-1 2,4-D. L'efficience la plus \ue9lev\ue9e de 40 % en terme d'\ue9limination du CBSV, avec 49 % de la survie de plantules \ue9tait observ\ue9e \ue0 36 \ub0C pendant 8 heures sous obscurit\ue9 et 40 \ub0C pendant 16 heures sous lumi\ue8re. Les r\ue9sultats indiquent que les techniques in vitro peuvent grandement promouvoir l'\ue9limination du CBSV et offrent ainsi un moyen de gestion de CBSD \ue0 travers la dissemination et la conservation des cultivars aussi populaires que susceptibles au SBSD

Detection of cowpea aphid-borne mosaic virus (CABMV) in cowpea by reverse transcription polymerase chain reaction

The occurrence of CABMV on cowpea ( Vigna unguiculata L. Walp) in Uganda was described recently in several studies. This study developed and optimised a reverse transcription polymerase chain reaction (RT-PCR) based assay for the detection of CABMV in leaf samples, and compared it to previous RT-PCR and ELISA assays. Use of the forward primer (CABFF1, 5'- GGT AAC AAY AGT GGR CAA CC-3') and the reverse primer (CABRR1, 5'- CTG AGC ACT CMA ACC GGG-3') yielded a product of ~ 1,642 bp. Amplicon sequencing and subsequent BLASTN analysis showed that Ugandan isolates were 89.3-94.3% identical indicating they belong to the same strain of CABMV. Phylogenetic analysis also placed the Ugandan isolates in the same cluster different from other isolates but closer to those from Burkina Faso. However, the previously reported RT-PCR assay (GF/GR primer pair) did not give the expected PCR fragment (221 bp) and gave no virus hits upon amplicon sequencing and sequence analysis. The ELISA assay did not differentiate between positive and negative samples. The newly developed RT-PCR assay for detecting CABMV, described in this study, has important applications for plant quarantine, resistance breeding, host range studies as well as epidemiological studies for the control of CABMV in the country.L\u2019apparition de CABMV sur le ni\ue9b\ue9 ( Vigna unguiculata (L.)) en Ouganda a \ue9t\ue9 d\ue9crite r\ue9cemment dans plusieurs \ue9tudes. Cette \ue9tude a d\ue9velopp\ue9 et optimis\ue9 un essai bas\ue9 sur la transcription inverse- r\ue9action en cha\ueene par polym\ue9rase (RT-PCR) pour la d\ue9tection du CABMV dans les \ue9chantillons de feuilles, et la compar\ue9 aux essais pr\ue9c\ue9dents bas\ue9s sur la RT-PCR et ELISA. L\u2019usage de l\u2019amorce direct (CABFF1, 5'- GGT AAC AAY AGT GGR CAA CC-3\u2019) et d\u2019amorce r\ue9verse (CABRR1, 5'- CTG AGC ACT CMA ACC GGG-3') a donn\ue9 ~ 1,642 bp. Le s\ue9quen\ue7age d\u2019amplicon et l\u2019analyse subs\ue9quente de BLASTN ont montr\ue9 que les isolats d\u2019Ouganda \ue9taient \ue0 89,3-94,3% identiques indiquant qu\u2019ils appartiennent \ue0 la m\ueame souche de CABMV. Les analyses phylog\ue9n\ue9tiques ont aussi plac\ue9 les isolats Ougandais dans la m\ueame classe qui est diff\ue9rente des autres isolats mais proche de ceux du Burkina-Faso. N\ue9anmoins, les essais de RT-PCR (GF/GR paire d\u2019amorces) pr\ue9c\ue9dents n\u2019ont pas donn\ue9 les fragments PCR esp\ue9r\ue9s (221 bp) et n\u2019ont donn\ue9 aucune d\ue9tection de virus \ue0 partir du s\ue9quen\ue7age d\u2019amplicon et de l\u2019analyse de la s\ue9quence. L\u2019essai de l\u2019ELISA n\u2019a pas diff\ue9renci\ue9 entre les \ue9chantillons positifs et n\ue9gatifs. L\u2019essai RT-PCR nouvellement d\ue9velopp\ue9 pour d\ue9tecter le CABMV, d\ue9crit dans cette \ue9tude, a d\u2019importantes applications pour la mise en quarantaine de la plante, s\ue9lection pour la r\ue9sistance, les \ue9tudes des gammes d\u2019h\uf4tes ainsi que les \ue9tudes \ue9pid\ue9miologiques pour le contr\uf4le du CABMV dans le pays

A Systematic Review and Meta-Analysis of Self-Guided Online Acceptance and Commitment Therapy as a Transdiagnostic Self-Help Intervention

Online Acceptance and Commitment Therapy (ACT) interventions use websites and smartphone apps to deliver ACT exercises and skills. The present meta-analysis provides a comprehensive review of online ACT self-help interventions, characterizing the programs that have been studied (e.g. platform, length, content) and analyzing their efficacy. A transdiagnostic approach was taken, including studies that addressed a range of targeted problems and populations. Multi-level meta-analyses were used to nest multiple measures of a single construct within their respective studies. A total of 53 randomized controlled trials were included (n = 10,730). Online ACT produced significantly greater outcomes than waitlist controls at post-treatment for anxiety, depression, quality of life, psychological flexibility, and all assessed outcomes (i.e. omnibus effect), which were generally maintained at follow-up. However, only psychological flexibility and all assessed outcomes at post-treatment were found to be significantly greater for online ACT when compared to active controls, with no significant follow-up effects. Overall, these results further clarify that ACT can be effectively delivered in an online format to target a wide range of mental health concerns, although it is less clear if and when online ACT is more efficacious than other online interventions

IN VITRO PROPAGATION OF THREE COMMERCIAL PASSIONFRUIT VARIETIES IN UGANDA

Small purple ( Passiflora edulis f. edulis ) and yellow ( P. edulis f. flavicarpa ) and KPF 4 (a cross between the two varieties) passionfruit varieties are of high economic importance in Uganda. Production of passionfruit is greatly constrained by viral diseases, leading to significant yield losses. This is aggravated by lack of adequate quantities of clean planting material. In vitro propagation through nodal sections is one way that has been successful in rapidly producing planting materials of vegetatively propagated crops that are clean and true-to-type. This study was aimed at obtaining optimum in vitro growth conditions for rapid micropropagation of the commercial passionfruit varieties in Uganda. Surface sterilised nodal sections from two month old plants were used as explants. For shoot regeneration, explants were cultured on Murashige and Skoog (MS) media, supplemented with varying concentrations of 6-Benzylaminopurine (BAP), either singly or in combination with Kinetin (KIN). Rooting MS media was fortified with varying concentrations of 1-Naphthalene acetic acid (NAA), either singly or in combination with BAP. MS medium supplemented with a combination of 2 mg l-1 BAP and 0.5 mg l-1 KIN, optimally supported shoot regeneration of the three passionfruit varieties. The average number of shoots and shoot height were 3.3 and 3.1 cm, respectively. Optimal root development was observed on MS media containing 3 mg l-1 NAA, with a mean number of 5.5 leaves and a length of 2.4 cm. The rooted in vitro plantlets were successfully established in a potting mixture containing loam soil and manure in ratio of 1:1.Les vari\ue9t\ue9s de fruit de la passion petit violet ( Passiflora edulis f. edulis ), jaune ( P. edulis f. flavicarpa ) et KPF 4 (croisement r\ue9alis\ue9 entre les deux vari\ue9t\ue9s pr\ue9c\ue9dentes) sont d\u2019une importance \ue9conomique tr\ue8s \ue9lev\ue9e en Ouganda. La production du fruit de la passion est sujette \ue0 aux maladies virales, causant d\u2019\ue9normes pertes de rendement. Ceci est aggrav\ue9 par l\u2019inexistence en quantit\ue9 suffisante des semences de qualit\ue9. La propagation In vitro au moyen des sections nodales, est un proc\ue9d\ue9 qui a connu du succ\ue8s dans la production rapide des semences de bonne qualit\ue9 chez les plantes \ue0 propagation vegetative. La pr\ue9sente \ue9tude a \ue9t\ue9 r\ue9alis\ue9e afin de d\ue9terminer les conditions optimales de croissance in vitro en vue d\u2019une micropropagation rapide des vari\ue9t\ue9s commerciales de fruit de la passion en Ouganda. Des sections nodales pr\ue9lev\ue9es sur des plants de fruit de la passion ages de deux mois, ont \ue9t\ue9 st\ue9rilis\ue9es en surface et utilis\ue9es comme explants. Pour la r\ue9g\ue9n\ue9ration plantulaire, les explants ont \ue9t\ue9 cultiv\ue9s sur des milieu de culture Murashige et Skoog (MS), additionn\ue9s de diverses concentrations de 6- Benzylaminopurine (BAP), soit uniquement ou en combinaison avec de la Kinetine (KIN). Le milieu de culture MS pour la croissance racinaire a \ue9t\ue9 renforc\ue9 avec diverses concentrations de 1-Naphthalene acide ac\ue9tique (NAA), soit uniquement ou en combinaison avec BAP. Le milieu MS additionn\ue9 de 2 mg l-1 BAP et 0,5 mg l-1 KIN, a permis une r\ue9g\ue9n\ue9ration optimale des explants des trois vari\ue9t\ue9s test\ue9es. Le nombre moyen de plantule et la longueur des racines \ue9taient respectivement de 3,3 et 3,1 cm. Un d\ue9veloppement racinaire optimal a \ue9t\ue9 observe sur milieu MS contenant 3 mg l-1 NAA, avec une moyenne de 5,5 feuilles et une longueur moyenne de 2,4 cm. les plantules in vitro ont repiqu\ue9es sur pots contenant un m\ue9lange de sol argileux et de la fumure dans des proportions 1:1

HERITABILITY ANALYSIS OF PUTATIVE DROUGHT ADAPTATION TRAITS IN SWEETPOTATO

Drought stress is a constraint to sweetpotato ( Ipomoea batatas L. (Lam)) production in many parts of Sub-Saharan Africa. In this region, crop farming is predominantly rain fed; therefore, breeding for drought tolerance is appropriate for addressing low sweetpotato productivity since the crop is largely produced by resource-limited farmers. As part of developing drought tolerant genotypes in Uganda, this study aimed at determining the nature of genetic control and heritability associated with selected drought adaptation traits. Ten randomly chosen clones from each family were evaluated for three traits; tuber yield, crop vigour and canopy cover as well as five traits (leaf senescence, leaf rolling, leaf retention, SPAD readings and root vertical pulling) at 80% field capacity and under no watering conditions for three weeks in a glasshouse. Diallel analysis revealed significant effects for both GCA and SCA, indicating both additive and non-additive gene actions were present. Baker\u2019s ratio was large in most traits (>0.50), indicating predominance of additive effects. Heritability coefficients were high in most traits (>0.50), indicating that genetic gains can be achieved by conventional breeding. The predominance of additive genetic control realised in this study implies that use of small numbers of parents with suitable GCA effects is most appropriate for drought tolerance improvement in sweetpotato.La s\ue9cheresse constitue une contrainte importante \ue0 la production de la patate douce ( Ipomoea batatas L. (Lam)) dans beaucoup de parties de l\u2019Afrique sub Saharienne. Dans cette r\ue9gion, l\u2019agriculture est \ue0 predominance pluviale, ainsi, l\u2019am\ue9lioration pour la tol\ue9rance \ue0 la s\ue9cheresse est appropri\ue9e pour adresser la faible productivit\ue9 de la patate douce d\u2019autant plus que la culture est largement produite par les fermiers \ue0 resources limit\ue9es. Comme contribution au d\ue9veloppement des genotypes tolerant la s\ue9cheresse en Ouganda, cette \ue9tude a pour but de d\ue9terminer la nature de l\u2019heritabili\ue9 et le contr\uf4le g\ue9n\ue9tique associ\ue9s aux traits d\u2019adaptation \ue0 la s\ue9cheresse. En suite, dix clones al\ue9atoirement choisis dans chaque famille \ue9taient \ue9valu\ue9s au champs pendant dix huit semaines pour trois traits dont le rendement en tubercules, la vigueur de la plante et la couverture de la canop\ue9e ainsi que cinq traits (la senescence foliaire, l\u2019enroulement de la feuille, la retention foliaire, ls lectures du SPAD et l\u2019attrait de la racine verticale) \ue0 80% de la capacit\ue9 au champ et sans r\ue9gime de conditions d\u2019arrosage pendant trois semaines dans une serre). L\u2019analyse Diall\ue8le a r\ue9v\ue9l\ue9 des effets significatifs pour le GCA et SCA, indicant la pr\ue9sence des actions additives et non additives de g\ue8nes. Le rapport de Baker \ue9tait large dans laplupart des traits (>0.50), indicant la pr\ue9dominance des effets addidifs. Les coefficients d\u2019heritabilit\ue9 \ue9taient \ue9lev\ue9s dans la plupart des traits (>0.50), montrant que des gains g\ue9n\ue9tiques peuvent \ueatre acquis par l\u2019am\ue9lioration conventionnelle. La pr\ue9dominance du contr\uf4le g\ue9n\ue9tique additif r\ue9alis\ue9 dans cette \ue9tude implique que l\u2019utilisation d\u2019un petit nombre de parents avec effets GCA appropri\ue9s est la plus indiqu\ue9e pour l\u2019am\ue9lioration de la tol\ue9rance \ue0 la s\ue9cheresse dans la patate douce