Isolation High Chlorophyll Fluorescence Mutants In Arabidopsis Thaliana And Functional Analysis Of PPT1 Gene

In this study, we characterize a T-DNA-tagged allele of pptl mutant, which was selected by its high chlorophyll fluorescence phenotype, and it possesses representative reticulate phenotype of pptl mutant. The affected gene in pptl encodes a phosphoenolpyruvate (PEP)/phosphate translocator (PPT) of the plastid inner envelope membrane. The import of PEP appears to be essential for plastid developments, since PEP as a key metabolite acts as precursors and intermediate for the primary and secondary plant products via the shikimate pathway. RT-PCR analysis revealed that in the mutant, the expression of corresponding PPT1 gene (ATPPTl at 5 g33320) was barely detectable compared with that in the WT plant.Under normal growth conditions, WT and mutant plants developed flowers within 8 wks. At wk 6, all leaves of WT were healthy and the leaf phenotype of pptl mutant is different between young and mature leaves. We compared the photosynthetic behavior on different leaf age at one developmental stage of pptl mutant. The FvlFm ratio, reflecting the maximal photosystem II photochemical efficiency, was not changed in different age leaves of WT. Instead, the chlorophyll fluorescence FvlFm ratio decreased from the central leaves to marginal ones in the mutant. Distinct color differences were observed in fluorescence image between the young leaves (orange) and the mature leaves (dark blue) of the 6-wk pptl mutant plants. Fluorescence decay kinetics reflected the rate of electron transfer from Qa" to Qb more precisely. In the 20d leaves of pptl mutant, the electron transfer in the PSII acceptor side was slightly affected compared with that in WT. More pronunciated inhibitory effects on the electron transfer in the PSII acceptor side were observed in the 40d leaves.We examined the steady state levels of photosynthetic thylakoid protein accumulation. Immunoblot analysis with the photosynthetic proteins antibodies showed the steady state levels of these proteins in the 40d leaves were decreased compared with that in the 20d leaves and that the changes of PSII proteins were correlated with that of Fv/Fm ratio in pptl mutant. These results indicated that the...