Photosynthetic gene Lhcf2 mRNA stability control in response to a herbivory induced aldehyde in a marine diatom

Dynamic challenges of biotic stress agents are prevalent in the life of a photosynthetic organism. One widely observed biotic stress defense mechanism is down- regulation of photosynthetic gene expression, but the mechanisms of down- regulation are unknown. In this study, the mechanism of photosynthetic gene regulation of a light harvesting complex gene was studied in the marine diatom Phaeodactylum tricornatum in response to a diatom derived toxic aldehyde, 2E,4E-decadienal (DD), which is released in response to herbivory. We have shown that Lhcf2, a strongly expressed LHC gene in P. tricornutum, was down-regulated to around 5 % within 1hr of DD treatment and 10-15% of original mRNA levels after 6 hr. No change in Lhcf2 transcription rates were detectable between the control and DD treated cells. Instead, assays of post-transcriptional mRNA metabolism showed that DD treatment reduced the Lhcf2 mRNA half-life. To our knowledge, this is the first report on the mechanism of biotic stress-induced photosynthetic gene down-regulation