Phenotypic and molecular screenings for determination of cassava mosaic disease (CMD) status in farmers' fields in Ebonyi State, Nigeria.

African cassava mosaic virus (ACMV) and East African cassava mosaic virus (EACMV) are among the major constraints to cassava productivity within tropical and sub-tropical regions, including Ebonyi State, Nigeria. Thus, virus indexing has become imperative to determine the status of cassava mosaic disease (CMD) in Ebonyi State, to implement appropriate preventive and control strategies. Seventy-eight cassava accessions obtained from different locations of Ebonyi State were phenotypically scored, using scales 1-5 depending on CMD symptomatic expressions, followed by multiplex-PCR and sequencing for validation. 11% of cassava accessions cultivated in Afikpo were resistant (RE) to ACMV compared to 8% of moderately-resistant (MR) accessions in Izzi and 55% of tolerant (TO) ACMV accessions in Ebonyi. 100% of cassava accessions in Onicha and 66% in Afikpo South were susceptible (SU) and highly susceptible (HS) to ACMV, respectively. With multiplex-PCR, 97.4% (ACMV) and 2.6% (EACMV) were positive. Dunn's multiple comparison tests of CMD mean incidence demonstrated differences (P < 0.05), except between RE and MR, and TO and MR. More transitions (A/G, C/T) compared to transversions (A/T, G/T), were detected, with nonsynonymous mutations (Leucine/Isoleucine; Valine/Isoleucine; Arginine/Lysine; Methionine/Isoleucine), and good bit-scores (91.13-99.07% identites; e-values of 7.00e-148-0.00e+00). Phylogeny resolved the sequences into five major groups. DNA sequencing validated the detected ACMV and EACMV species. This study revealed variants of ACMV and low adoption of RE and MR cassava accessions in the farmers' fields. The findings will guide in getting disease-free and resistant varieties as planting materials to significantly mitigate the CMD spread in Ebonyi State, Nigeria.

Sphenostylis stenocarpa (ex. A. Rich.) Harms., a Fading Genetic Resource in a Changing Climate: Prerequisite for Conservation and Sustainability.

The southeastern part of Nigeria is one of the major hotspots of useful plant genetic resources. These endemic species are associated with a rich indigenous knowledge and cultural diversity in relation to their use and conservation. Sphenostylis stenocarpa (ex. A. Rich.) Harms., (African Yam Bean (AYB)), is one such crop within the family of Fabaceae. Its nutritional and eco-friendly characteristics have value in ameliorating malnutrition, hidden hunger and environmental degradation inherent in resource-poor rural and semi-rural communities throughout Africa. However, lack of information from the custodians of this crop is limiting its sustainable development. Therefore, ethnobotanical surveys on the diversity, uses, and constraints limiting the cultivation and use of the crop in southeastern Nigeria were carried out. Five-hundred respondents were randomly selected and data collected through oral interviews and focused group discussion (FGD). Semi-structured questionnaires (SSQ) were also used to elicit information from a spectrum of AYB users comprising community leaders, farmers, market women and consumers in five States. Results showed that the majority of the respondents lacked formal education and were of the age group of 40-50 years, while the female gender dominated with limited access to land and extension officers. Seed coat colour largely determined utilization. Long cooking time, requirement for staking materials, aging of farmers and low market demand were among the major constraints limiting further cultivation and utilization of AYB. In-situ conservation was by hanging dried fruits by the fireside, beside the house, storing in earthenware, calabash gourds, cans and bottles. It is concluded that there is urgent need to scale up conservation through robust linkages between contemporary scientific domains and indigenous peoples in order to harness and incorporate the rich indigenous knowledge in local communities for enhanced scientific knowledge, biodiversity conservation and its sustainable utilization for food security.