Restoration of tensile strength in bark samples of Ficus benjamina due to coagulation of latex during fast self-healing of fissures

The functions of plant latex have been discussed for a long time. Today, many studies support a defence mechanism as being its main function. A role as a self-healing mechanism was never attributed to the coagulation of latex. In this study we quantified the contribution of the coagulation of Ficus benjamina (weeping fig) latex to a restoration of the mechanical properties of the bark after external lesions. Tensile tests of F. benjamina bark were conducted either immediately after injury or at various latency times after injury. A significant increase in the tensile strength of bark samples until 30 min after injury was found, and this effect could be attributed to the coagulation of plant latex alone. The tensile strength remains nearly constant until several hours or days after injury. Then, very probably due to other mechanisms such as cell growth and cell proliferation, the tensile strength begins to increase slightly again. The coagulation of latex seals lesions and serves as a quick and effective pre-step of subsequent, more effective, long-lasting self-healing mechanisms such as cell growth and proliferation. Thus, a fast self-healing effect can be included in the list of functions of plant latex.