Morphological and genotypic characterization of African nightshade cultivars

Characterization of African nightshade cultivars is important in identifying the genetic diversity that exists among different cultivars. Genetic diversity can be utilized in breeding programs to develop improved African nightshade cultivars that are high yielding (both leaf and fruit yields) and resistant to biotic and abiotic stresses. The aim of this study was to assess the existence of genetic diversity in different African nightshade cultivars through morphological and genotypic characterization. Germplasm were obtained from the Gene bank of Kenya, AVRDC-TZ and from Kenyan farmers. For morphological characterization the African nightshade cultivars were planted at KALRO Muguga and at KALRO Kisii and scored for several agro morphological characters based on International Plant Genetic Resources Institute (IPGRI) descriptors. Data was collected on both quantitative (plant height, internode length, leaf width leaf length, leaf length: leaf width ratio and number of berries per panicle) and qualitative (growth habit, stem color, leaf shape, leaf color, flower color, berry color and berry size) traits. Morphological data was then subjected to analysis of variance (ANOVA) using GenStat Version 15 while cluster analysis was done using DARwin 6 statistical software. Results showed that there was phenotypic variation among cultivars since they grouped into three clusters (AB and C). There were significant (P ≤ 0.05) differences between cultivars in plant height, internode length, number of primary branches, leaf size and number of berries per panicle. Correlation studies showed significant strong correlation between leaf width and leaf length (r=0.949**) as well as between leaf size and leaf width (r=-0.772**). Plant height showed significant positive correlation with internode length (r=0.651**), number of branches (r=0.407**) while there was a negative significant correlation between plant height and leaf size (-0.409**). Number of berries and internode length were also significantly correlated (r=0.538**). The significant variations seen among African nightshade cultivars showed that there exists diversity amongst them. Molecular characterization was done using SSR markers on twenty seven African nightshade cultivars. 5SSR primers yielded reproducible bands with 2 of them (CA158 and STI 001) were polymorphic while the rest (SSR 111, SSR 63 and TSR2) were monomorphic. The dendrogram revealed that the cultivars grouped into three clusters. These findings show that there is rich diversity both within and among African nightshade species which can be exploited for further breeding work.