PLB143: Evolution of Crop Plants, UC Davis


A very recent paper on

The origin of cassava (Manihot esculenta)

Olsen KM, Schaal BA. 1999. Evidence on the origin of cassava: phylogeography of Manihot esculenta.

Proc. Nat. Acad. Sci. USA 96: 5586-5591

(Summary by P. Gepts )


Some links on cassava


Introduction

Fig. 1. Sampling locations for populations of M. esculenta subsp. flabellifolia (squares) and M. pruinosa (circles) in Brazilian states surrounding the Amazon basin. Black squares indicate populations of subspecies flabellifolia found to share one or more haplotypes with cassava (M. esculenta subsp. esculenta) accessions. Populations within the oval together contain all of the shared cassava haplotypes (see Results and Discussion). TO, Tocantins; GO, Goiás; MT, Mato Grosso; RO, Rondônia; AC, Acre Map of Brazil



Materials & Methods


Results & Discussion

Table 1. Variation in the G3pdh locus
Region Mutation No.
Exons Nonsynonymous 1

Synonymous 9
Intron Substitutions 47

Indels: 7

1 bp (2)

3 bp (3)

19 bp (1)

25 bp* (1)
* Minisatellite region with 1-5 repeats
Fig. 2. The G3pdh gene tree. Haplotype letters correspond to those in Table 2. Shapes around letters indicate the taxa in which haplotypes were found. Each line between haplotypes represents a mutational step, with numbers on lines indicating the variable base pair position. For branches of more than one mutational step without intermediate haplotypes (or side branches), the relative placement of the mutations along the branch is arbitrary. Insertions (i) and deletions (d) relative to the center of the tree are indicated after the base pair number, followed by the number of bases involved. Two different substitutions at position 463 are designated as a and b. Homoplasious (H) mutations are indicated after the base pair number. Numbers in bold print indicate the number of 25-bp minisatellite motifs associated with each haplotype.