Extensin arabinoside chain length is modulated in elongating cotton fibre.

Cotton fibre provides a unicellular model system for studying cell expansion and secondary cell wall deposition. Mature cotton fibres are mainly composed of cellulose while the walls of developing fibre cells contain a variety of polysaccharides and proteoglycans required for cell expansion. This includes hydroxyproline-rich glycoproteins (HRGPs) comprising the subgroup, extensins.

Exocyst mutants suppress pollen tube growth and cell wall structural defects of hydroxyproline O-arabinosyltransferase mutants.

HYDROXYPROLINE O-ARABINOSYLTRANSFERASEs (HPATs) initiate a post-translational protein modification (Hyp-Ara) found abundantly on cell wall structural proteins. In Arabidopsis thaliana, HPAT1 and HPAT3 are redundantly required for full pollen fertility. In addition to the lack of Hyp-Ara in hpat1/3 pollen tubes (PTs), we also found broadly disrupted cell wall polymer distributions, particularly the conversion of the tip cell wall to a more shaft-like state.