QTLs detection under natural infection of Moniliophthora perniciosa in a cacao F2 progeny with Scavina-6 descendants. In: Agrotrópica v. 26 p. 65-72, 2014.

Abstract

Studies to determine the genetic bases to witches’ broom disease (WBD) resistance in Theobroma cacao L. were carried out in order to identify different genetic sources of resistance and to improve the efficiency of selection using molecular markers. A major QTL for WBD resistance and linked to Scavina 6 - the mains source of resistance, was detected in chromosome 9 from a F2 Scavina 6 x ICS 1 progeny. In this paper, phonotypical quantification of vegetative and flower cushions brooms was done in the same progeny growing in two fields: F2 -1M and F2 -1C; respectively with 62 individuals and 142 individuals, observed over a period from 2003 to 2008. QTLs analyses were carried out with MapQTL 5.0 software to confirm the presence in chromosome 9 of the previously detected QTL. A significant instability of this QTL was observed with a LOD and the percentage of variation explained decreasing and moving in the confidence interval of mTcCIR157. Others QTLs of resistance were also detected such as one in Ch2, which was found in an opposite direction. These new QTLs analyzes, under natural infections of M. perniciosa, suggest a change in the host and pathogen relationships.