The origin of angiosperms has been a focus of botanical research. Although macrofossils and microfossils have suggested that angiosperms may have earlier occurrence, there are some scholars reluctant to accept these fossil records and their implications. To resolve this conflict studying more fossils using new technology is helpful. Obvious differences exist between pollen of seed plants and spore of ferns. Applying the MFCFM technology, here we report a half pollen grain with a mosaic combination of fluorescent spectral features of angiosperms and ferns from the Jurassic of China. Although the mother plant is still mysterious, the features of this fossil pollen grain apparently demands a new thinking on pollen and its evolution.
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.