Genetic Diversity of White Yam (Dioscorea rotundata Poir) Accessions Maintained in Tissue Culture and Cultivated in Field using Simple Sequence Repeat (SSR) Markers and Morphological Characterization

Dioscorea rotundata is a staple food crop for millions of people in the tropical and subtropical regions. In vitro germplasm conservation is a very useful tool in yam improvement strategies but very little is known about the genetic integrity and stability of in-vitro conserved yam plants. In this study, 42 accessions from in vitro and field populations were genotyped using 11 microsatellite markers and 23 morphological descriptors to assess variability within and between accessions. Out of the 23 morphological variables used, 13 were identified as most discriminate and were used to cluster the accessions into 4 clusters using the unweighted pair group arithmetic mean average (UPGMA). Accession maintained in field as well as in in-vitro showed high genetic similarity (R2 = 0.91, p-value: 1e-04). Out of the 42 accessions analyzed, nine accessions maintained in the field and in-vitro displayed different genetic profiles. This study provided basic information on the possible somaclonal variation of yam accessions maintained through in-vitro. Further study with advanced tools such as next-generation sequencing is required to elucidate the nature of the observed variation within clones.

Leaf epidermal characteristics of Lotus subgenus Acmispon (Fabaceae: Loteae) and a numerical taxonomic evaluation

This paper describes the leaf epidermal characteristics of the New World species of Lotus L. subgenus Acmispon Raf. (Fabaceae: Loteae), computes their phenetic relationships based on morphological and anatomical characters, and compares these results with previous classifications and a recent phylogenetic hypothesis for the group based on morphological data. Leaves of 16 species of Acmispon were cleared and examined using light microscopy. Data on epidermal cells, stomata, stomatal index, and trichomes were described and summarized. To test the taxonomic value of epidermal characters and to ascertain phenetic relationships, we performed two numerical analyses using unweighted pair-group arithmetic average clustering. Results of the numerical analysis (16 operational taxonomic units (OTUs) × 13 epidermal characters) suggested that epidermal characteristics are insufficient to resolve sections Simpeteria and Microlotus. An additional analysis (16 OTUs × 23 characters) demonstrated that epidermal micro morphological features, together with other characters, are useful and informative for distinguishing these two sections. Results generated by the latter analysis accord well with earlier classifications and a previous phylogenetic hypothesis by showing that the sections Simpeteria and Microlotus are coincident with the two monophyletic subgroups Grandiflorus and Salsuginosus, respectively, inferred using cladistic analysis.Key words: Acmispon, epidermis, Fabaceae, Loteae, Lotus, Microlotus, Simpeteria.