Tapetal 3-Ketoacyl-Coenzyme A synthases are involved in pollen coat
lipid accumulation for pollen-stigma interaction in Arabidopsis
Abstract
Pollen coat lipids form an outer barrier to protect pollen itself and
play essential roles in pollen-stigma interaction. However, the precise
molecular mechanisms underlying pollen coat lipids production,
deposition, regulation and function during anther development remain
largely elusive. 3-ketoacyl-coenzyme A synthases (KCS) are involved in
fatty acid elongation or very long chain fatty acid (VLCFA) synthesis.
Here, we identified six members of Arabidopsis KCS family expressed in
anther. Of them, KCS7, KCS15 and KCS21 express in tapetal cells at
stages 8-10. Further analysis demonstrated that they act downstream of
Male sterility1 (MS1), a regulator for late tapetum development. The
kcs7/15/21 triple-mutant is fertile. Both cellular observation and lipid
staining showed pollen coat lipid was decreased in triple mutant. After
landing on stigma, the wild-type pollen was hydrated in about 5 min
while the triple mutant pollen took about 10 min. Pollen tube growth of
the triple mutant was also delayed. These results demonstrate the
pathway in tapetum to produce pollen coat lipid, and reveal the roles of
tapetal-derived pollen coat lipid for pollen-stigma interaction.