Mutation in Arabidopsis MOR1 gene impairs endocytosis in stamen filament cells and results in anther indehiscence

Anther dehiscence is a crucial step for pollen grains release and male fertility. Filaments, which transport water, nutrients and hormones to the anthers, are important for anther dehiscence. In this study, we characterized the Arabidopsis MICROTUBULE ORGANIZATION 1 ( MOR1 ) gene that involves in the filament functions and plays important roles in anther dehiscence. The Arabidopsis microtubule organization 1–1 ( mor1-1 ) mutant exhibited an anther indehiscence phenotype at 24 °C. Such the defect did not occur at a lower temperature (19 °C). Further analysis indicated that both the cortical microtubule (CMT) organization and plasma membrane homeostasis were drastically impaired and disturbed in mor1-1 filament cells under the growth conditions of 24 °C. Transmission electron microscopy and FM4-64 up-take assays showed that endocytosis process in the mor1-1 filament cells were disrupted at 24 °C. Furthermore, the cortical-associated RFP tagged clathrin light chain foci were reduced in the mor1-1 filament cells. These results suggested that the MOR1 mediated CMT organization is important for clathrin-mediated endocytosis in the filament cells, and critical for anther dehiscence in thermosensitivity.