XVI International Botanical Congess

Hydroxyproline-rich glycoproteins (HRGPs) are cell wall structural proteins that were reported to prevent microtubule depolymerization in protoplasts exposed to 4?C (Akashi et al., 1990), suggesting an interaction between HRGPs and microtubules. The requirement of HRGPs for cortical microtubule organization was investigated, via immunocytochemistry, in Arabidopsis by inhibiting HRGP hydroxylation with the proline analog 3, 4-dehydro-L-proline (Dhp). One hour after Dhp treatment, cortical microtubules were disorganized in cells with shape that did not differ from that of control. Other microtubule arrays were not affected. These results suggest that HRGPs are specifically required for cortical microtubule organization. This work supported in part by an Esau Post-doctoral fellowship, UC Davis.