HGT IN DIATOMS. “These genes were not found in any other photosynthetic eukaryotes (other than other heterokonts), and it is believed that they have provided diatoms with increased flexibility in their regulatory and metabolic networks that may have contributed to their evolutionary success.” (HGT = Horizontal Gene Transfer).
http://jxb.oxfordjournals.org/content/early/2012/01/20/jxb.err441.full