An intraspecific genetic map of water yam (<Emphasis Type="Italic">Dioscorea alata</Emphasis> L.) based on AFLP markers and QTL analysis for anthracnose resistance |
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Authors: | D Petro T J Onyeka S Etienne S Rubens |
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Institution: | 1.INRA, UR979 Unité de Recherche en Productions Végétales,Petit-Bourg, Guadeloupe,France |
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Abstract: | Water yam (Dioscorea alata L.) is the most widely cultivated food yams. Despite its importance, its production is limited by anthracnose disease caused
by Colletotrichum gloeosporioides (Penz.). The use of resistant yam varieties is the most reliable approach of management of this disease. The speed and precision
of breeding can be improved by the development of genetic linkage maps which would provide the basis for locating and hence
manipulating quantitative traits such as anthracnose resistance in breeding programmes. An F1 diploid population was developed
by crossing ‘Boutou’ a female clone (with field resistance to anthracnose) with ‘Pyramide’ (susceptible). A linkage map was
generated with 523 polymorphic markers from 26 AFLP primer combinations. The resulting map covered a total length of 1538 cM
and included 20 linkage groups. It is the most saturated of all genetic linkage maps of yam to date. QTL analysis of anthracnose
resistance was performed based on response to two isolates of C. gloeosporioides. Resistance to anthracnose appeared to be inherited quantitatively. Using a LOD significance threshold of 2.6 we identified
a total of nine QTLs for anthracnose resistance. The phenotypic variance explained by each QTL ranged from 7.0 to 32.9% whereas
the total amount of phenotypic variation for anthracnose resistance explained by all significant QTLs varied from 26.4 to
73.7% depending on the isolate and the variable considered. These QTLs displayed isolate-specific resistance as well as broad
spectrum resistance. The availability of molecular markers linked to the QTLs of anthracnose resistance will facilitate marker-assisted
selection in breeding programmes. |
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