Dear Editor,Pollen hydration is a prerequisite for pollen germination and subsequent pollen tube growth.As a result of two decades of biochemical studies and genetic identification of the eceriferum (cer) male-sterile mutants,the very-long-chain fatty acid (VLCFA) lipids in the pollen coat have been well known to play a critical role in pollen hydration (Preuss et al.,1993;Fiebig et al.,2000;Hiscock and Allen,2008).VLCFAs are referred to as fatty acids with 20 or more carbons,which are synthesized through four sequential reactions catalyzed by 3-ketoacyI-CoA synthase (KCS),3-ketoacyI-CoA reductase (KCR),3-hydroxyacyI-CoA dehydratase,and enoyl reductase (ECR).Among all the reactions,KCS-mediated condensation is the rate-limiting step and determines the length of the final acyI-CoA products (Haslam and Kunst,2013).KCS6 (also known as CER6,POP1,and CUT1)catalyzes the production of C28 fatty acyI-CoAs and is essential for pollen hydration (Fiebig et al.,2000;Haslam and Kunst,2013).