Abstract: Apoplast is an important compartment outside of plasma membrane of the plant cell and is the source of various primary signals. Biotic or abiotic stimuli can first cause the alteration in apoplastic signaling system; on the other hand, apoplast provides a convenient pathway for cell-cell communication, and therefore plays a key role in regulation of cell differentiation, organ genesis, and growth development of plants. This review summarized recent advance in the research of apoplastic polypeptides and proteins in our lab.