Abstract
Pollen coat is a surface structure of Arabidopsis pollen grains, which consists mainly of proteins and lipids. These components are synthesized in tapetal cells and are deposited on the pollen surface after the tapetal cells are ruptured. Pollen coat is important for pollen fertility. The EXTRACELLULAR LIPASE4 (EXL4) and EXL6, which belong to the GDSL lipases, are abundant proteins in Arabidopsis pollen coat. To reveal their function, we carried out several experiments. Both EXL4 and EXL6 were strongly expressed in the flower buds of stage 10 to middle 12, where the lipid components of pollen coat were synthesized actively. The plants that carry both a T-DNA insertion in EXL6 and an RNAi construct for EXL4 showed reduced fertility. Thus it is proposed that both EXL4 and EXL6 are expressed in the tapetum and have important roles to create lipid component such as free fatty acids enriched in the pollen coats.
