2011 Annual Report
1a.Objectives (from AD-416)
Evaluate patterns of genetic variation among populations of sweetpotato-related species in order to provide a quantitative assessment of the genetic structure of Ipomoea batatas (sweetpotato) and it’s closely related species which will facilitate the determination of the extent of the relevant gene pool for selective breeding of this crop (sweetpotato).
1b.Approach (from AD-416)
Fifty populations of section Batatas species including; I. batatas, I. x leucantha, I. tiliacea, I. cordatotriloba, I. trifida and I. triloba will be analyzed for their molecular and morphological diversity. DNA sequence data for gene regions for two basic-helix-loop-helix (bHLH) transcription factors of the anthocyanin biosynthetic pathway will be obtained for each population. These data will be used to determine the pattern of nucleotide diversity and haplotype diversity among sampled populations. The identified haplotypes will be used to examine population structure of the samples. A comprehensive morphological analysis will be developed. The morphological data will be used to determine the pattern of variation among populations related to the named species. In addition, congruence between the pattern of morphological variation and results from the molecular analyses of genetic structure will be examined.
This research relates to inhouse Objective 1: Strategically expand the genetic diversity in genebank collections and improve associated information for priority vegetables, sorghum, peanut, subtropical/tropical legume, and warm-season grass genetic resources.
The objective of this research project is to apply a phylogeographic approach to consider population structure/species relationships within the hybridizing complex that includes Ipomoea batatas and its relatives. The initial efforts concentrated on mining existing sequence data from available sources. This led to a study of the phylogeography of Ipomoea trifida based on published data from the Rausher lab. Sequence data was analyzed to compare automated alignment programs Multiple Sequence Alignment by Log-Expectation (MUSCLE), Multiple Alignment with Fast Fourier Transform (MAFFT), Simultaneous Alignment and Tree Estimation (SatE), Tree-based Consistency Objective Function For alignment Evaluation (T-COFFEE) and three manual alignments. These alignments were then analyzed using Bayesian phylogenetic methods (MrBayes) and a strong phylogenetic hypothesis was developed showing three major clades within the Batatas group; Ipomoea batatas, I. trifida, I. tabascana, with I. littoralis sister to this clade; I. umbraticola and I. ramossisima, and then the remaining species in a separate clade (using I. setosa as an outgroup). This study is currently being written up and will be submitted to Systematic Botany. Also, over 200 accessions of members of Ipomoea section Batatas have been amassed. This has included recent donations of samples from the Missouri Botanical Garden, as well as the combined material from our collection and Germplasm Resources Information Network (GRIN). Each accession with the best locality information available was put in a database. These materials are being planted in the greenhouse for Deoxyribo Nucleic Acid (DNA) extraction, as well as morphological studies.
Progress was monitored via email correspondence with the investigator.