Wireless sensor networks (WSNs) are prone to node/link failures, message losses, and dynamic node joins and departures. For instance, in data gathering applications that constitute a common type of applications in WSNs, links between nodes and their parent in the data gathering tree may be broken. Protocols supporting such applications should adapt their behaviour to guarantee reliable wireless communications keeping a low overhead. In particular, this paper focuses on the optimization of a known coloring algorithm called SERENA. The coloring technique is used to assign colors to nodes such that no two interfering nodes share the same color. Each color is mapped to a time slot to constitute a TDMA cycle defining the schedule of the nodes activity. The goal is to enhance the robustness of the algorithm and let it tolerate link failures and topology changes without recoloring the network. Our solutions proactively select one or more parent backups and guarantee that the coloring remains valid if a parent is replaced by its backup. Simulation results show that reliability is obtained at the price of an increase in the data delivery delays and the energy consumption.