Involvement of arabinogalactan proteins in protonemata development from cultured cells of Marchantia polymorpha

Abstract

Arabinogalactan proteins (AGPs) are abundant plant cell‐surface proteoglycans widely distributed in plant species. Crossed electrophoresis patterns of AGPs isolated from cultured cells before and after protonemata development differed, indicating that AGPs are involved in protonemata differentiation and development. Moreover, the addition of β‐glucosyl Yariv reagent (βglcY), which binds specifically to AGPs, inhibits protonemata differentiation in cells of the liverwort Marchantia polymorpha L. cultured in protonemata‐inducing medium. Transmission electron microscopic examination revealed that βglcY caused conspicuous disorder at the cell surface and the accumulation of abnormal structures between the plasma membrane and the cell wall. These results suggest that AGPs/βglcY complexes caused disturbances at the cell surface and inhibited cell‐wall synthesis required for protonemata differentiation. Our results indicate that AGPs play a significant role in cell‐wall synthesis during the protonemata‐differentiation process of M. polymorpha.