Cold Stress Effects on PSI Photochemistry in Zea mays: Differential Increase of FQR-Dependent Cyclic Electron Flow and Functional Implications

in the dark, indicating a higher capacity forcyclic electron flow (CEF) around PSI in cold-stressed maizeleaves. Furthermore, the increased PSI-dependent CEF(s)was associated with a much higher stromal electron poolsize and 56% lower capacity for state transitions comparedwith control plants. To examine NADP(H) dehydrogenase(NDH)- and ferredoxin:plastoquinone oxidoreductase(FQR)-dependent CEF in vivo, the post-illumination transi-ent increase of F