Identification of QTL Involved in the Production of Rooted Cuttings in a Segregating Mapping Population of Theobroma cacao L. in Brazil

Various diseases are responsible for considerable economic losses for cacao producers in the Americas and elsewhere in the world. Protective fungicides are ineffective and disease management involving repeated phytosanitary removals increases labor costs. The best alternative is the use of resistant cultivars and the large-scale production of this superior plant material through rooted cuttings is therefore a good option.

In this experiment, rooted cuttings were produced by the “Instituto Biofábrica de Cacau” from a segregating mapping population of a cross between ‘TSH 1188’ and ‘CCN 51’ present at the Mars Center for Cocoa Science in Barro Preto, Bahia, Brazil, following a protocol in which plagiotropic shoots were collected, dipped in indole-3-butyric acid to stimulate rooting, planted in small tubes and irrigated at regular intervals. After 60 days, the acclimatization of the rooted cuttings started with reduction of irrigation to harden the plants. Three months after initial staking, we investigated the percentage of successfully rooted cuttings and used the recently developed genetic linkage map, based on the 459 trees of the segregating mapping population, to perform a QTL analysis using MapQTL. We discuss the identification of five QTL on four different chromosomes and the potential use of some  SNP markers  in Marker-Assisted Selection to select clones with better aptitude to produce rooted cuttings.