A meta-QTL analysis of disease resistance traits of Theobroma cacao L.

Theobroma cacao, is a tropical understorey tree that is a major economic resource to several tropical countries. However, the crop is under increased threat from several diseases that are responsible for 30% loss of harvest globally. Although QTL data related to the genetic determinism of disease resistance exist in cocoa, QTL mapping experiments are heterogeneous, thus making comparative QTL mapping essential for marker assisted selection (MAS). Sixteen QTL experiments were analysed, and the 76 QTLs detected were projected on a progressively established consensus map. Several hot spots, with QTLs related to different Phytophthora species and other diseases, were observed. The likely number of real QTLs was estimated by using a meta-analysis implemented in BioMercator software. There was a twofold reduction in average confidence interval observed when compared to the confidence interval of individual QTLs. This alternative approach confirms the existence of several sources of resistance to different diseases of cocoa which could be cumulated in new varieties to increase the sustainability of cocoa resistance using MAS strategies.