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In angiosperms,the precise delivery of male to female gametes during double fertilization depends on complex cell-to-cell communications between male（pollen tube,PT） and female gametophytes.We provide solid evidence to demonstrate that,at the male side,these male-female communications including pollen tube reception were primarily controlled by the tube cells,rather than sperm cells.It has been reported that receptor-like kinases（RLKs）,such as FERONIA in synergid cells and ANXUR1/2 in the pollen tubes,act as key components in the pollen tube reception.We identified two Arabidopsis pollen tube-specific plasma membrane-localized receptor-like kinases,Buddha’s Paper Seal 1（BUPS1） and 2（BUPS2）,that are also involved in pollen tube integrity control because pollen tubes of bupsl bups2 rupture immediately after germination in vitro.Moreover,reactive oxygen species（ROS） production was affected in the bupsl mutant.Interestingly,physical interactions between the ectodomains of BLIPS 1/2 and those of ANX1/2 were detected.Meanwhile,two pollen-specific RALF peptides,RALF4 and 19,serve as the signal ligands for BUPS1/2 and ANX1/2 since ralf4 ralf19 double mutant exhibits similar PT precocious rupture phenotypes to those of bupsl bups2 and anxl anx2 both in vitro and in vivo,and both peptides interact with both BUPS1/2 and ANX1/2.Furthermore,we found that a female tissue-derived RALF peptide,RALF34,could induce pollen tube burst at nanomolar concentrations.RALF34 peptide is expressed highly in ovules,and is able to compete with RALF4/19 for the interaction with BUPS1/2-ANX1/2 receptor complex.Furthermore,two BUPS/ANX-interacting proteins（BAIP1 and 2） that are specifically expressed and localized in the plasma membrane of PTs were identified.Simultaneous inactivation of these two BAIP genes resulted in PT precocious rupture,similar to those of bupsl bupsl and anxl anx2.Interestingly,interactions between BAIPs and BUPSs or ANXs were remarkably strengthened when RALF4/19 peptides were present,suggesting that BAIPs are part of the BUPS/ANX receptor complex controlling PT integrity.Therefore,a model of PT integrity control is proposed,and evidences of other factors involved in this regulatory process are also discussed.