Changes of activities and resistance to excitation pressure of photosystems during the development of Prunus avium leaves
The excess light energy beyond the utilization ability of photosynthetic carbon assimilation is termed excitation pressure,which can lead to photoinhibition.In this study,the changes in photosystem Ⅰ(PSⅠ)and photosystm Ⅱ(PSⅡ)activities and their resistance to excitation pressure during the development of leaves from Prunus avium'Tieton'was analyzed by 820 nm light absorption and chlorophyll fluores-cence technology.The results show that the activities of both PSⅠ and PSⅡ increased gradually during leaf development,and the PSⅠ activity was much lower than PSⅡ in young leaves,indicating that PSⅡ develops earlier than PSⅠ.To explore the resistance of PSⅠ and PSⅡ to excitation pressure,continuous high light or repeated short-pulse light treatments were applied respectively to induce PSⅡ or PSⅠ photoinhibition.The resistance of PSⅡ to excitation pressure increased gradually as leaf development,while the resistance of PSⅠ to excitation pressure initially decreased and then increased.Therefore,this study suggests that the development of PSⅠ and PSⅡ activities,as well as their resistance to excitation pressure,are not synchro-nized during leaf development.The photoprotection mechanisms of PSⅠ and PSⅡ may be relatively inde-pendent.The resistance of PSⅠ to excitation pressure was not related to the P700 oxidation ratio(P700+)and plastoquinone reduction degree(Fs/Fm).Further research is needed to investigate the mechanisms un-der changing resistance of the PSⅠ to excitation pressure during the development of P.avium leaves.
NETL
NSTL
万方数据
