Splits internally a 1,3-beta-glucan molecule and transfers the newly generated reducing end (the donor) to the non-reducing end of another 1,3-beta-glucan molecule (the acceptor) forming a 1,3-beta linkage, resulting in the elongation of 1,3-beta-glucan chains in the cell wall. Involved in spore wall assembly. Localizes to the ascospore periphery during sporulation. Strongly induced during sporulation. Belongs to the glycosyl hydrolase 72 family.