SUPPRESSION OF psbP AND psbQ GENES IN NICOTIANA TABACUM BY RNA INTERFERENCE TECHNIQUE

摘要

The extrinsic proteins present in the luminal space of thylakoids are shown to play crucial roles in optimizing the water-oxidizing activity in photosystem II (PSII). One of the components, PsbO, is ubiquitous among all oxygen-evolving photosyntheticorganisms from cyanobacteria to higher plants, whereas the other components are variable in different classes of organisms. In higher plants PsbO, PsbP and PsbQ proteins are the major components of luminal extrinsic proteins, and they have been extensively analyzed from biochemical and structural standpoints in the past decades (for review, see Seidler 1996). However, their physiological functions in vivo have been poorly understood due to the insufficient gene silencing for these proteins. In this study, we have therefore applied the RNA interference (RNAi) technology to generate two transgenic tobacco plants, pshPir and psbQir, in which the expression of psbP and psbQ genes was selectively and significantly suppressed. These targeted extrinsic proteins are unique to green algae and higher plants, and their cyanobacterial counterparts in regard to the function have been reported to be PsbV and PsbU. However, quite recently, PsbP and PsbQ homologues were found in PSII preparations from Synechocystis 6803 (Thornton et al 2004). Therefore, understanding the physiological roles of PsbP and PsbQ in higher plants is also of interest from evolutional standpoint.