A better understanding of population structure and genetic diversity among cassava germplasm for African cassava mosaic disease and fresh root yield traits is useful for cassava improvement programme. Phenotype-based ...A better understanding of population structure and genetic diversity among cassava germplasm for African cassava mosaic disease and fresh root yield traits is useful for cassava improvement programme. Phenotype-based selection for these traits is cumbersome due to phenotypic plasticity and difficulty in screening of phenotypic-induced variations. This study assessed quantitative trait loci (QTL) regions associated with African cassava mosaic disease (ACMD) and fresh storage root yield (FSRY) in 131 cassava (Manihot esculenta) genotypes using a genome-wide association study (GWAS). The single nucleotide polymorphism (SNP) loci and associated candidate genes, when validated, would be a valuable resource for marker-assisted selection in the breeding process for development of new cassava genotypes with improved resistance to ACMD and desirable high root yield. Population structure analysis using 12,500 SNPs differentiated the 131 genotypes into five distinct sub-groups (K = 5). Marker-trait association (MTA) analysis using the generalized linear model identified two QTL regions significant for ACMD and three for FSRY. This study demonstrated that DArTseq markers are useful genomic resources for genome-wide association studies of ACMD and FSRY traits in cassava for the acceleration of varietal development and release.展开更多
It has been observed that farmers adopt only a small number of the “improved” cultivars. A nationwide germplasm collection exercise in February 2018 provided the opportunity to collect indigenous technical knowledge...It has been observed that farmers adopt only a small number of the “improved” cultivars. A nationwide germplasm collection exercise in February 2018 provided the opportunity to collect indigenous technical knowledge (ITK) of the diversity of cassava varieties in terms of: their morphology, growth characteristics, uses (of tubers and leaves) and desirable characteristics. The objective is to see to what extent the objectives of the plant breeders are consistent with what farmers’ value. We performed 405 structured and semi-structured interviews with informants who were selected based on “purposive household sampling”. We found a considerable turn-over in cassava varieties, just over a third (45) have been in cultivation for at least 40 years, however, since the end of the civil war an additional 25 varieties are cultivated, while others varieties seem to have disappeared. One major issue with estimating turnover of varieties is whether the same variety might have several local names, and conversely the same name may be applied to different cultivars. Farmers overwhelmingly use ITK to select and preserve cassava germplasm for future use. Farmers have a clear preference for: sweet taste, high yield, early maturity and easy cooking and preferentially adopt cultivars that have those qualities. Cassava is primarily a human food eaten boiled or fried, some are processed into fufu and gari, and uses as livestock feed and medicine are reported but at low levels. The information produced during this study could help plant breeders choose selection criteria that will ensure their efforts are adopted and sustainable, the importance of preserving the genetic resources of local cultivars is also highlighted.展开更多
Background Sub-Saharan Africa experiences a disproportionate amount of pediatric surgical disease,with 80%of children lacking access to timely,affordable,and safe surgical care.This study aims to characterize the burd...Background Sub-Saharan Africa experiences a disproportionate amount of pediatric surgical disease,with 80%of children lacking access to timely,affordable,and safe surgical care.This study aims to characterize the burden of disease and outcomes of pediatric surgical conditions at Connaught Hospital,the main pediatric referral hospital in Sierra Leone.Methods This retrospective and hospital-based study included children up to 15 years old who were operated on between 2015 and June 2016 at Connaught Hospital in Freetown,Sierra Leone.Descriptive and inferential statistics were used to characterize the distribution of disease and compare all variables against age category and mortality.Findings A total of 215 patients were included in this study of which 72.5%(n=132)were male and 27.5%(n=50)were female.Most of the patients were diagnosed with congenital anomalies(60.9%;n=131).However,infection was the leading diagnosis(60.5%;n=23)among patients aged 5–10 years(n=38).Inguinal hernia was the leading condition(65.0%;n=85)among patients presenting with a congenital anomaly.The condition with the highest mortality was infections(17.0%;n=8),followed by other conditions(9.1%;n=2)and congenital anomalies(3.1%;n=4).Based on the results of this study,over 7000 children with inguinal hernias remain untreated annually in Freetown,Sierra Leone.Conclusion This study quantifies the burden of surgical disease among children,a foundational step toward the prioritization of pediatric surgical care in national health agendas,the development of evidence-based interventions,and the strategic allocation of resources in Sierra Leone.展开更多
文摘A better understanding of population structure and genetic diversity among cassava germplasm for African cassava mosaic disease and fresh root yield traits is useful for cassava improvement programme. Phenotype-based selection for these traits is cumbersome due to phenotypic plasticity and difficulty in screening of phenotypic-induced variations. This study assessed quantitative trait loci (QTL) regions associated with African cassava mosaic disease (ACMD) and fresh storage root yield (FSRY) in 131 cassava (Manihot esculenta) genotypes using a genome-wide association study (GWAS). The single nucleotide polymorphism (SNP) loci and associated candidate genes, when validated, would be a valuable resource for marker-assisted selection in the breeding process for development of new cassava genotypes with improved resistance to ACMD and desirable high root yield. Population structure analysis using 12,500 SNPs differentiated the 131 genotypes into five distinct sub-groups (K = 5). Marker-trait association (MTA) analysis using the generalized linear model identified two QTL regions significant for ACMD and three for FSRY. This study demonstrated that DArTseq markers are useful genomic resources for genome-wide association studies of ACMD and FSRY traits in cassava for the acceleration of varietal development and release.
文摘It has been observed that farmers adopt only a small number of the “improved” cultivars. A nationwide germplasm collection exercise in February 2018 provided the opportunity to collect indigenous technical knowledge (ITK) of the diversity of cassava varieties in terms of: their morphology, growth characteristics, uses (of tubers and leaves) and desirable characteristics. The objective is to see to what extent the objectives of the plant breeders are consistent with what farmers’ value. We performed 405 structured and semi-structured interviews with informants who were selected based on “purposive household sampling”. We found a considerable turn-over in cassava varieties, just over a third (45) have been in cultivation for at least 40 years, however, since the end of the civil war an additional 25 varieties are cultivated, while others varieties seem to have disappeared. One major issue with estimating turnover of varieties is whether the same variety might have several local names, and conversely the same name may be applied to different cultivars. Farmers overwhelmingly use ITK to select and preserve cassava germplasm for future use. Farmers have a clear preference for: sweet taste, high yield, early maturity and easy cooking and preferentially adopt cultivars that have those qualities. Cassava is primarily a human food eaten boiled or fried, some are processed into fufu and gari, and uses as livestock feed and medicine are reported but at low levels. The information produced during this study could help plant breeders choose selection criteria that will ensure their efforts are adopted and sustainable, the importance of preserving the genetic resources of local cultivars is also highlighted.
文摘Background Sub-Saharan Africa experiences a disproportionate amount of pediatric surgical disease,with 80%of children lacking access to timely,affordable,and safe surgical care.This study aims to characterize the burden of disease and outcomes of pediatric surgical conditions at Connaught Hospital,the main pediatric referral hospital in Sierra Leone.Methods This retrospective and hospital-based study included children up to 15 years old who were operated on between 2015 and June 2016 at Connaught Hospital in Freetown,Sierra Leone.Descriptive and inferential statistics were used to characterize the distribution of disease and compare all variables against age category and mortality.Findings A total of 215 patients were included in this study of which 72.5%(n=132)were male and 27.5%(n=50)were female.Most of the patients were diagnosed with congenital anomalies(60.9%;n=131).However,infection was the leading diagnosis(60.5%;n=23)among patients aged 5–10 years(n=38).Inguinal hernia was the leading condition(65.0%;n=85)among patients presenting with a congenital anomaly.The condition with the highest mortality was infections(17.0%;n=8),followed by other conditions(9.1%;n=2)and congenital anomalies(3.1%;n=4).Based on the results of this study,over 7000 children with inguinal hernias remain untreated annually in Freetown,Sierra Leone.Conclusion This study quantifies the burden of surgical disease among children,a foundational step toward the prioritization of pediatric surgical care in national health agendas,the development of evidence-based interventions,and the strategic allocation of resources in Sierra Leone.
