Evaluation of Water Yam (Dioscorea alata L.) Germplasm for Reaction to Yam Anthracnose and Virus Diseases and their Effect on Yield

Use of genetic resistance is the most practical and economic way to manage major diseases of yams. In a search for sources of resistance, 40 water yam (Dioscorea alata L.) accessions from Benin, Ghana, Nigeria and Puerto Rico were screened under natural disease infection conditions in Ibadan, Nigeria. The accessions were evaluated at 1, 3 and 6 months after planting (MAP) for severity of yam anthracnose and viral diseases. The effect of the pathogens on yield was also evaluated at harvest 9 MAP. There were significant differences (P < 0.001) between accessions for severities of anthracnose and viral diseases. Eight (20%) of them had lower anthracnose area under disease progress curves (AUDPC) values than the resistant check while 10 (25%) had AUDPC values below the trial mean. There were significant variations (P < 0.001) in yield components among the accessions. There was significant negative correlation of anthracnose severity with fresh tuber yield (r = −0.51) and with number of tubers per plot (r = −0.40). Similarly, significant negative correlations were observed of virus disease severity with fresh tuber yield (r = −0.78) and number of tubers per plot (r = −0.65). Linear regression models also showed that the fresh yield had significant negative relationships with anthracnose (R² = 0.26) and viral (R² = 0.62) diseases. The accessions identified as resistant constitute a valuable resource for breeding of resistant germplasm.     

solGS: a web-based tool for genomic selection

Background

Genomic selection (GS) promises to improve accuracy in estimating breeding values and genetic gain for quantitative traits compared to traditional breeding methods. Its reliance on high-throughput genome-wide markers and statistical complexity, however, is a serious challenge in data management, analysis, and sharing. A bioinformatics infrastructure for data storage and access, and user-friendly web-based tool for analysis and sharing output is needed to make GS more practical for breeders.

Results

We have developed a web-based tool, called solGS, for predicting genomic estimated breeding values (GEBVs) of individuals, using a Ridge-Regression Best Linear Unbiased Predictor (RR-BLUP) model. It has an intuitive web-interface for selecting a training population for modeling and estimating genomic estimated breeding values of selection candidates. It estimates phenotypic correlation and heritability of traits and selection indices of individuals. Raw data is stored in a generic database schema, Chado Natural Diversity, co-developed by multiple database groups. Analysis output is graphically visualized and can be interactively explored online or downloaded in text format. An instance of its implementation can be accessed at the NEXTGEN Cassava breeding database, http://cassavabase.org/solgs.

Conclusions

solGS enables breeders to store raw data and estimate GEBVs of individuals online, in an intuitive and interactive workflow. It can be adapted to any breeding program.

Electronic supplementary material

The online version of this article (doi:10.1186/s12859-014-0398-7) contains supplementary material, which is available to authorized users.     

Cassava Trait Preferences of Men and Women Farmers in Nigeria: Implications for Breeding

Nigeria is the world’s largest cassava producer, hosting a diverse array of cassava farmers and processors. Cassava breeding programs prioritize “common denominator” traits in setting breeding agendas, to impact the largest possible number of people through improved varieties. This approach has been successful, but cassava adoption rates are less than expected, with room for improvement by integrating traits in demand by farmers and processors. This paper aims to inform breeding priority setting, by examining trait and varietal preferences of men and women cassava farmer/processors. Men and women in eight communities in Southwest and Southeast Nigeria were consulted using mixed methods. Women and men had significantly different patterns of cassava use in the Southwest. Fifty-five variety names were recorded from the communities demonstrating high genetic diversity maintained by growers, especially in the Southeast. High yield, early maturity, and root size were most important traits across both regions, while traits women and men preferred followed gender roles: women prioritized product quality/cooking traits, while men placed higher priority on agronomic traits. Trait preference patterns differed significantly between the Southeast and Southwest, and showed differentiation based on gender. Patterns of access to stem sources were determined more by region and religion than gender.     

Early onset of neurological features differentiates two outbreaks of Lassa fever in Ebonyi state,Nigeria during 2017–2018

Lassa fever (LF) is an acute viral haemorrhagic illness with various non-specific clinical manifestations. Neurological symptoms are rare at the early stage of the disease, but may be seen in late stages, in severely ill patients.The aim of this study was to describe the epidemiological evolution, socio-demographic profiles, clinical characteristics, and outcomes of patients seen during two Lassa fever outbreaks in Ebonyi State, between December 2017 and December 2018.Routinely collected clinical data from all patients admitted to the Virology Centre of the hospital during the period were analysed retrospectively. Out of a total of 83 cases, 70(84.3%) were RT-PCR confirmed while 13 (15.7%) were probable cases. Sixty-nine (83.1%) patients were seen in outbreak 1 of whom 53.6% were urban residents, while 19%, 15%, and 10% were farmers, students and health workers respectively. There were 14 (16.8%) patients, seen in second outbreak with 92.9% rural residents. There were differences in clinical symptoms, signs and laboratory findings between the two outbreaks. The case fatality rates were 29.9% in outbreak 1 and 85.7% for outbreak 2. Neurological features and abnormal laboratory test results were associated with higher mortality rate, seen in outbreak 2. This study revealed significant differences between the two outbreaks. Of particular concern was the higher case fatality during the outbreak 2 which may be from a more virulent strain of the Lassa virus. This has important public health implications and further molecular studies are needed to better define its characteristics.