Triple plagiotropic branch in coffee: a new promising mutant?

Abstract

Coffee tree is a shrub with dimorphic branches. The orthotropic stem grows vertically with two near-horizontal plagiotropic branches, per node, in opposite phyllotaxy. The consecutive nodes of the orthotropic stem are organized in parastichies. We report here mutant plants of Coffea arabica with triple plagiotropic branch, resulted from the whorled phyllotaxy of the orthotropic stem. In mutant plants three plagiotropic branches in the same node are separated by angles of approximately 120^o, while in normal plants two plagiotropic branches in the same node are separated by angles of approximately 180^o. In mutant plants the angles of the parastichies increase approximately 50^o clockwise between consecutive nodes, while in normal plants the angles increase approximately 87^o. The plant architecture is changed. The triple plagiotropic branch is a putative mutant with potential to be explored in coffee breeding programs. The hypotheses for the origin of the mutation and the research perspectives are discussed.

Key words:
Coffea; mutant; breeding; orthotropic; dimorphism