Effects of rewatering on light-harvesting chlorophyll a/b-protein complex of photosystem II in Zea mays

The amount and conformation of light-harvesting chlorophyll a/b-protein complex (LHC II) of photosystem II and the expression of a gene encoding for LHC II were investigated when maize (Zea mays L.) seedlings were exposed to water stress and rewatering. The relative water content (RWC) and water potential in maize leaves decreased markedly after 72 h of water stress; the content of chlorophyll and apoproteins of LHC II and the mRNA level of a gene encoding for LHC II were reduced pronouncedly, but not recovered after 24 h of rewatering. However, the conformation of LHC II in thylakoids was also altered by water stress but could be recovered by 24 h of rewatering. The authors proposed that two ways of dissipating relative excess excitation energy may be encountered in the photosynthetic membrane. A fast way is by changing the conformation of LHC II and another relatively slow way is the reduction of components of LHC II, through which the reduction of apoproteins of LHC II can be regulated partly at the transcript level.