Effects of water stress and rewatering on turnover and gene expression of photosystem II reaction center polypeptide D1 in Zea mays

Photosystem II oxygen evolution capacity, the steady-state level of photosystem II (PSII) reaction center polypeptide D1 and its transcript and template levels inZea mays L. (Xinyu No. 4) under water stress and rewatering were studied. The results indicated that PSII and whole-chain electron transport capacities decreased slightly under moderate water stress and appreciably under severe water stress, and could not recover to control level upon rewatering. The results of western and northern blots showed that the content of PSII reaction center polypeptide D1 changed as a similar pattern to PSII and whole-chain electron transport capacities. Dot blot analysis for DNA showed that there was no obvious response of the template level of D1 to water stress or rewatering. From the results, it was concluded that PSII was the major site affected by water stress, where the functional loss of PSII could be attributed to the reduction of PSII reaction center polypeptide D1, which may be caused by the decrease in its transcript level. Rewatering could only ameliorate slightly under moderate water stress but could not recover to control level under severe water stress.