Abstract Detail

Population Genetics

Bradbury , Elizabeth Jane [1], Duputié, Anne [2], Delêtre, Marc [3], Roullier, Caroline [2], Emshwiller, Eve [4], Mckey, Doyle [5].

Genetic Differentiation of Bitter and Sweet Cassava (Manihot esculenta Crantz) at the Global and Continental Levels: new analyses distinguish between competing hypotheses of genetic drift and migration.

Cassava (Manihotesculenta Crantz), one of the most important tropical food crops, is commonly divided into two main use-categories: those varieties that are processed prior to consumption ("bitter") and those that are cooked without processing ("sweet"). These use-categories are biochemically differentiated as those roots that contain less than 50 mg/kg fresh weight of HCN ("sweet") and those whose roots contain more than this amount ("bitter"). However, very little research has been conducted investigating patterns in genetic structure among "sweet" and "bitter" cassava populations at scales greater than a village or national level. The objective of this study is to provide initial insight into patterns of genetic differentiation among bitter and sweet cassava on the continental and global scales. Using eight microsatellite loci, we genotyped 363 cassava accessions from South America, Africa, and the South Pacific. Sampling included 139 bitter accessions and 214 sweet accessions. Results show a pattern of genetic division between bitter and sweet accessions in South America. However, this pattern is not observed in Africa. Results are inconclusive regarding potential founder effect in Africa. The loss of genetic differentiation in Africa is likely the result of either genetic drift in the African bitter populations over time or the introduction of "sweet" alleles into the African bitter populations through migration. Recently conducted analyses help distinguish between these competing hypotheses.

Broader Impacts:

1 - University of Wisconsin-Madison, Botany, 430 Lincoln Drive , Birge Hall, Madison, WI, 53706, USA
2 - Centre National de la Recherche Scientifique, Centre d'Ecologie Fonctionelle et Evolutive, Montpellier, France
3 - Muséum Nationale d'Histoire Naturelle, Paris, France
4 - University Of Wisconsin-Madison, Botany Dept, 321 Birge Hall, 430 Lincoln Drive, Madison, WI, 53706-1313, USA
5 - CEFE CNRS, 1919 ROUTE DE MENDE, MONTPELLIER, F-34293, France

Keywords:
domestication
crop migration
clonally propagated crops
Isolation with Migration Model
microsatellite.

Presentation Type: Oral Paper:Papers for Topics
Session: 26
Location: Portland Room/Chase Park Plaza
Date: Tuesday, July 12th, 2011
Time: 11:45 AM
Number: 26015
Abstract ID:464