强光下硫化氢通过促进光系统II的活性来缓解水稻的光抑制

以水稻品种‘II优084’为材料,测定了强光胁迫下,水稻光合速率、叶绿素荧光快速诱导曲线（OJIP）以及O2ˉ·和H2O2在水稻叶片中积累的影响。结果表明强光胁迫下,水稻的净光合速率及气孔导度下降;光系统II（PSII）反应中心关闭的比例以及电子传递链中光系统II受体侧原初醌受体（QA）的还原程度增加;PSII反应中心电子传递的量子产额、能量以及传递到下游电子链的比率下降;光抑制下PSII的过剩能量向PSI的状态装换减少;自由基的产生增加。而施加作为硫化氢（H2S）供体的外源硫氢化钠（NaHS）后,上述影响PSII活性的指标的负变化被缓解,捕光天线复合体LHC通过在两个光系统之间的移动,来调节两个光系统的能量分配。强光下H2S处理能促进LHC离开PSII,与PSI结合,从而减少PSII分配的激发能,增加PSI分配的激发能,缓解了PSII的过度还原。以上结果表明外源H2S通过促进PSII的光合活性来缓解水稻光抑制伤害。

Hydrogen Sulfide Alleviates Rice Photoinhibition by Promoting the Activity of Photosystem II in Strong Light Stress

Rice cultivar ＇Ilyou 084＇ is our study material. We determined the rice＇s photosynthesis, fast chlorophyll fluorescence induction curve （OJIP）, the accumulation of O2 and H202 in rice leaf in strong light stress. The data revealed that rice＇s photosynthesis and stomatal conductance were reduced; the proportion of the closed PSII reaction centers and the degree reduction of the primary quinone acceptor of PSII acceptor side in the electron transport chain （QA） were increased; the quantum yield of electron transfer and energy in PSII reaction center, and the ratio of energy which passed to the downstream electronics chain were declined; the transformation of excess energy of PSII to PSI under photoinhibition was declined; the production of free radicals was increased. While treated with exogenous sodium hydrosulfide （NariS）, a donor of hydrogen sulfide （H2S）, these changes which have an negative effective on the activity of PS II were alleviated, especially can promote more energy transform from PSII to PSI, thus easing the over-reduction of PSII and improving the activity of PSII. These results illustrate that exogenous H2S can promote the photosynthetic activity of PSII to mitigate the damage caused by photoinhibition.