GENETIC LINKAGE MAP CONSTRUCTION AND IDENTIFICATION OF QTLS AFFECTING TIME OF INITIAL VEGETATIVE BUDBREAK IN APPLE (MALUS X DOMESTICA BORKH.)

Mild winter temperatures, as experienced in the Western Cape region of South Africa, result in the inefficient release of bud dormancy in apple trees during spring.
Global warming, together with an increasing awareness regarding the environmental impact of chemical sprays, has led to the need to breed apple cultivars with a lower chilling requirement that are better adapted to local climatic conditions.
Previous work has shown an important heritable component in the control of the dormancy-related characteristic, time of initial vegetative budbreak (IVB), in apples.
In this work we describe the generation of genetic linkage maps, using apple framework map markers [Liebhard et al. (2002) and Silfverberg-Dilworth et al. (2006)] and a series of new EST-derived microsatellite (EST-SSR) markers, implemented on two mapping populations.
These mapping populations, being ‘Anna’ x ‘Golden Delicious’ and ‘Anna’ x ‘Sharpe’s Early’, segregate for time of IVB and QTLs affecting this trait have been identified on several linkage groups.
The reported results are a step forward in our aim to unravel the genetic factors underlying the complex nature of dormancy and dormancy related traits.
The identification of marker genotypes associated with time of IVB will enable the application of marker-assisted-selection (MAS) in the breeding of apple cultivars with a lower chilling requirement that will be beneficial for local production, ensuring that South Africa remains competitive in the global apple export market.

XII EUCARPIA Symposium on Fruit Breeding and Genetics

M.M. van Dyk, I.F. Labuschagne, D.J.G. Rees

dormancy, genetic control, SSR, MAS, CR

https://doi.org/10.17660/ActaHortic.2009.814.99