THESEUS1 (THE1) is a component of the CrRLK1L-RALF signaling complex specifically responsible for establishing the polytubey block at the Arabidopsis septum. Genetic and biochemical analyses demonstrate that THE1, together with FERONIA, ANJ and HERK1, forms a receptor complex that senses pollen tube-derived RALF peptides, thereby establishing a barrier to prevent the emergence of multiple pollen tubes from the septum.
Li et al. (Thu,) studied this question.