COLE, R.A., SYNEK, L., ŽÁRSKÝ, Viktor, FOWLER, J.E. SEC8, a Subunit of the Putative Arabidopsis Exocyst Complex, Facilitates Pollen Germination and Competitive Pollen Tube Growth. Plant Physiology. 2005, 138(4), 2005-2018. ISSN 0032-0889. E-ISSN 1532-2548.

The exocyst, a complex of eight proteins, contributes to the morphogenesis of polarized cells in a broad range of eukaryotes. The gene encoding one exocyst component ortholog, AtSEC8, is expressed in pollen and vegetative tissues of Arabidopsis. Genetic studies utilizing an allelic series of six independent T-DNA mutations reveal a role for SEC8 in male gametophyte function. Three T-DNA insertions in SEC8 cause an absolute, male-specific transmission defect. In vivo assays indicate that these mutant pollen grains are unable to germinate a pollen tube. The other three T-DNA insertions are associated with a partial transmission defect, such that the mutant allele is transmitted through the pollen at a reduced frequency. The partial transmission defect is only evident when mutant gametophytes must compete with wild-type gametophytes. These data support the hypothesis that one function of the putative plant exocyst is to facilitate the initiation and maintenance of the polarized growth of pollen tubes.