Functional Analysis of Three Rice Chloroplast Transit Peptides

Chloroplast transit peptides (CTPs) can be used to transport non-chloroplastic proteins into the chloroplasts. Here, we studied the CTPs of three rice (Oryza sativa L.) chloroplast-localized proteins and found that their CTPs could be used to transport non-chloroplast-localized proteins into the chloroplasts. Fusion proteins lacking the CTP remained located in the cytoplasm. Furthermore, we constructed green fluorescent protein fusion vectors with the three CTPs and three non-chloroplast-localized proteins, Ghd10, MULTI-FLORET SPIKELET1 (MFS1), and SHORTENED UPPERMOST INTERNODE 1 (SUI1). After transforming these constructs into rice protoplasts, the fusion proteins all localized in the chloroplasts. Collectively, our results showed that these CTPs can transport non-chloroplast-localized proteins into the chloroplasts, and more importantly, these CTPs can be applied to engineer chloroplast metabolism.